Black Soldier Fly for Biodiesel production

21.02.2017  /  Scienceandmore  /  Category: Animal Biology

Large amounts of organic wastes accumulate worldwide every year. These wastes comprise for instance of slaughterhouse wastes (approximately 500 million tonnes in the EU annually), whey from cheese production (approximately 50 million tonnes in the EU annually), kitchen and food wastes, and wastes from crop plants, such as crop straw. In attempts to reduce the amount of organic wastes, fat from slaughterhouse wastes is used for the production of bioplastics by the non-pathogenic bacterium Cupriavidus necator for instance (1). In attempts to simultaneously access the waste’s intrinsic energy, organic wastes high in lignocellulose, which is a major component of the cell walls in woody plants, are used to obtain biogas, such as methane, by digestion with anaerobic bacteria (2).

Even though these waste recycling methods reduces the amount of waste, there are still large amounts of organic wastes unutilised. Another way to exploit these resources is the production of biodiesel. Commonly, edible oils from rapeseed, sunflower, and soybean are utilised for biodiesel production. However, these plants are specifically cultivated for biodiesel production. In this way, the production cost of biodiesel is approximately 1.5 times higher than that for conventional mineral diesel. Significantly, the majority of the costs arise from crop production (3,4,5).

In a practical and straightforward alternative to using oil from crop plants, the oils and fats from kitchen and food waste are used instead. In this way, food crops could be channelled into the food production instead of biodiesel production (3,6). The necessity of this transition is apparent considering that the world population will increase to an estimated 9.7 billion by 2050 (7,8).

In addition to the utilisation of oils and fats from kitchen and food waste, the use of the solid residue after oil and fat extraction have been considered for biodiesel production. For this purpose, black soldier fly larvae (BSFL) are reared on these residues and subsequently their fat is extracted. The fat of BSFL meets most of the requirements of the European biodiesel standard EN 14214, and has similar fuel properties as biodiesel from rapeseed oil. Thus, kitchen and food wastes could be used in two ways to obtain fat for biodiesel production (9).

Ultimately, BSFL grow faster, have a higher biomass, and require less area compared to vegetables or even microalgae that also have been proposed for biodiesel production (4).

In 2012, a research team in China obtained almost 24 g of biodiesel from the fat of 1000 BSFL reared on 1 kg of solid organic waste residue. The residue was also reduced by almost 62 % by the BSFL within 7 days (3).

A study with 2000 BSFL that were reared on a mixture of rice straw and kitchen and food waste at several ratios for 10 days showed a production of up to 44 g of biodiesel (10).

In contrast, a study with 500 BSFL that were reared on fermented corncobs, which were previously used for biogas production, for 8 days, only 3.2 g of biodiesel were produced from the BSFL fat. Notably, the fat content in these BSFL was very low. The significantly lower amount of produced biodiesel compared to the previous studies could be attributed to the low nutrition value of fermented corn cobs (2). The fat content of BSFL after all depends on their rearing substrate, and it can be increased by providing a fat-rich substrate (9).

Another study with approximately 1000 BSFL that were reared on cattle, pig or chicken manure yielded 35.5 g, 57.8 g and 91.4 g of biodiesel, respectively (10). This, again, could be attributed to the different nutritional values of the manures.

Besides the rearing substrate for BSFL, different fat extraction methods could also account for the different quantities of fat from BSFL that, subsequently, is used for biodieel production. Mechanical pressing for instance results in low extraction yields, whereas solvent extraction yields higher amounts but require large amounts of solvents (4).

Eventually, the utilisation of a specific rearing substrates and fat extraction method has to be evaluated ecologically and economically for individual biodiesel production operations.

Overall, BSFL could be utilised for biodiesel production from organic wastes. This could, on one hand, reduce the amounts of organic waste, while simultaneously using its still remaining resources, and, on the other hand, channel food crops into food production instead of biodiesel production.

References

1. Kunasundari, B., Murugaiyah, V., Kaur, G., Maurer, F. H. J., & Sudesh, K. (2013) Revisiting the Single Cell Protein Application of Cupriavidus necator H16 and Recovering Bioplastic Granules Simultaneously. PLoS ONE, 8(10), e78528.

2. Li, wu & Li, Qing & Zheng, Longyu & Wang, Yuanyuan & Zhang, Jibin & Ziniu, yu & Zhang, Yanlin. (2015) Potential biodiesel and biogas production from corncob by anaerobic fermentation and black soldier fly. Bioresource technology. 194:276-82.

3. Zheng, Longyu & Li, Qing & Zhang, Jibin & Ziniu, yu. (2012) Double the biodiesel yield: Rearing black soldier fly larvae, Hermetia illucens, on solid residual fraction of restaurant waste after grease extraction for biodiesel production. Renewable Energy. 41, 75-9.

4. Wang, C., Qian, L., Wang, W., Wang, T., Deng, Z., Yang, F., Xiong, J.., Feng, W. (2017) Exploring the potential of lipids from black soldier fly: new paradigm for biodiesel production (I). Renewable Energy. 111: 749-56.

5. Canakci M, Sanli H. (2008) Biodiesel production from various feedstocks and their effects on the fuel properties. J Ind Microbiol Biotechnol. 35:431–41.

6. Patil, P.D., Gude, V.G., Reddy, H.K., Muppaneni, T., Deng, S.G. (2012) Biodiesel production from waste cooking oil using sulfuric acid and microwave irradiation processes. J Environ Pro. 3:107-13.

7. Tilman, D., Balzer, C., Hill, J., & Befort, B. L. (2011) Global food demand and the sustainable intensification of agriculture. Proceedings of the National Academy of Sciences of the United States of America, 108(50), 20260-4.

8. United Nations, Department of Economic and Social Affairs, Population Division (2015) World Population Prospects: The 2015 Revision, Key Findings and Advance Tables. Working Paper No. ESA/P/WP.241.

9. Li Q, Zheng L, Cai H, Garza E, Yu Z, Zhou S. (2011) From organic waste to biodiesel: black soldier fly, Hermetia illucens, makes it feasible. Fuel. 90:1545e8.

10. Zheng, Longyu & Hou, Yanfei & li, wu & Yang, Sen & Li, Qing & Ziniu, yu. (2012). Biodiesel production from rice straw and restaurant waste employing black soldier fly assisted by microbes. Energy. 47. 225-29.

Lion’s mane lets neurons grow

More Details

19.02.2018  /  Scienceandmore  /  Category: Human Biology

Lion’s mane (scientifically Hericium erinaceus) is an edible mushroom that has been used in traditional Chinese medicine for a long time. In recent years, this white, globular-shaped and rotund mushroom has been investigated for its beneficial effects on humans, especially for its neuron growth promoting effects in the brain (neurogenesis).

Could it be that lion’s mane has an actual effect on neuron growth, or is it just another disappointing “miracle drug” and temporary hype?

brain mycelium

Biochemical analysis of lion’s mane mushroom found a wide variety of bioactive compounds, but two compounds in particular caught the attention of researchers: hericenones and erinacines. Both compounds have been shown to induce Nerve Growth Factors (NGFs) biosynthesis in nerve cells. NGFs activate cell differentiation and promote growth of neurons, as well as re-myelination of neurons. Myelin is an essential component of neurons and crucial for their function (1).

NGF belongs to the protein family of neurotrophins. Research data strongly suggests that neurotrophins are essential factors for the survival and differentiation of nerve cells. Decreased production of neurotrophins seems to be involved in the development of neurodegenerative diseases.

Neurotrophins would have been interesting compounds in treating neurodegenerative diseases, however, their high molecular weight prevents them from crossing the blood-brain barrier, and thus reaching the brain. The NGF-inducing hericenones and erinacines in lion’s mane mushrooms, on the other hand, seem to cross the blood brain barrier, and thus induce growth of neurons in the brain (2).

Investigations in cell cultures showed increased expression of genes that are associated with NGF synthesis upon administration of several erinacines from lion’s mane mushrooms. It was found that these compounds potentiate NGF-induced outgrowth from neurons. This added to the perception that lion’s mane mushroom affects survival and differentiation in nerve cells and displays anti-dementia activity. Therefore, intake of lion’s mane mushroom could potentially reduce the risk of developing neurodegenerative diseases (2).

In a study with rats, erinacine administration resulted in an upregulation of NGF in two brain areas, the locus caeruleus and the hippocampus. These brain areas are usually affected in patients with dementia and Alzheimer’s disease. In accordance with these results, erinacine administration in mice that exhibit symptoms equal to Alzheimer’s and Parkinson’s disease ameliorated the symptoms of both diseases (2,3,4).

Mice with impaired learning and memory that were fed lion’s mane mushrooms performed better in a memory test compared to mice that were not given the mushroom. The mice also regained a sense of curiosity and spend more time exploring novel objects. These results indicate that lion’s mane mushroom administration improves cognitive impairments and could be utilised in the treatment of cognitive dysfunctions such as Alzheimer’s disease (5).

In a 23 days study, mice were injected with a compound called amyloid ß peptide directly into the fluid in the brain which led to impaired learning and memory in these mice, specifically impaired spatial short-term and visual recognition memory. Administration of lion’s mane mushrooms, however, resulted in better performance in a memory test, accompanied by regaining a sense of curiosity in these memory-impaired mice. The mice spend more time exploring novel objects than mice that were not given lion’s mane mushroom. Examination of the mice brains revealed amyloid plaque formation similar to the one observed in Alzheimer’s patients. Amyloid plaques are involved in inflammation of brain tissue, impair neuron transmission, and associated with nerve degeneration. It is believed that amyloid plaque formation is a marker for Alzheimer’s disease. Overall, these results indicate that lion’s mane mushroom administration improves cognitive impairments linked to amyloid plaque formation. Lion’s mane mushroom could be utilised in the treatment of cognitive dysfunctions such as Alzheimer’s disease. However, lion’s mane represented 5 % of the whole mouse diet, which would translate to a substantial amount of daily human food intake. (5).

These results are promising, but, in fact, results obtained in the mouse model do not necessarily translate to humans. Fortunately, the effects of lion’s mane mushroom have also been studied in humans.

In a 16 weeks investigation with 30 Japanese men and women between the age of 50 to 80, who exhibited mild cognitive impairment, lion’s mane administration substantially improved their cognitive function. The men and women were tested at weeks 8, 12 and 16 and showed significantly higher scores in cognitive function tests than the control group. Crucially, the cognitive function increased with the duration of lion’s mane mushroom intake. The differences to the control group were greatest at week 16. During the investigation, the subjects were given 250 mg of lion’s mane mushroom daily. However, the beneficial effects decreased after the administration of lion’s mane mushroom was discontinued. The researchers thus concluded that a continuous intake is necessary to maintain the beneficial effects on cognitive functions. The researchers speculated that the promotion of NGF synthesis by compounds in lion’s mane could contribute to the prevention or alleviation of Alzheimer’s disease (6).

An important point that should not be disregarded is the palatability of lion’s mane mushroom. Ingestion of the mushroom itself does not present a health risk even after long-term consumption. However, some people have reported mild troubles with digestion but not to the point where intake has to be discontinued (6).

Overall, the research results are promising, and lion’s mane could contribute to the prevention or at least mitigation of cognitive impairment diseases. With increasing age, everybody will eventually suffer from cognitive impairment in some sort. Maintaining cognitive faculties would enhance the personal quality of life as well as the community’s quality of life.

Another very interesting area for research would be the impact of lion’s mane mushroom on healthy individuals. Would the mushroom-derived promotion of NGF synthesis actually improve cognitive functions? It is hard to speculate on the impact and further investigations are necessary to draw conclusions.

References

1. Lai PL, Naidu M, Sabaratnam V, Wong KH, David RP, Kuppusamy UR, Abdullah N, Malek SN. (2013) Neurotrophic properties of the Lion’s mane medicinal mushroom, Hericium erinaceus (Higher Basidiomycetes) from Malaysia. Int J Med Mushrooms. 15(6):539-54.

2. Zhang, C.-C., Cao, C.-Y., Kubo, M., Harada, K., Yan, X.-T., Fukuyama, Y., & Gao, J.-M. (2017). Chemical Constituents from Hericium erinaceus Promote Neuronal Survival and Potentiate Neurite Outgrowth via the TrkA/Erk1/2 Pathway. International Journal of Molecular Sciences, 18(8), 1659.

3. Tsai-Teng, T., Chin-Chu, C., Li-Ya, L., Wan-Ping, C., Chung-Kuang, L., Chien-Chang, S., Chi-Ying, H.F., Chien-Chih, C., Shiao, Y.J. (2016) Erinacine A-enriched Hericium erinaceus mycelium ameliorates Alzheimer’s disease-related pathologies in APPswe/PS1dE9 transgenic mice. J. Biomed. Sci. 23(1):49.

4. Kuo, H.C., Lu, C.C., Shen, C.H., Tung, S.Y., Hsieh, M.C., Lee, K.C., Lee, L.Y., Chen, C.C., Teng, C.C., Huang, W.S., et al. (2016) Hericium erinaceus mycelium and its isolated erinacine A protection from MPTP-induced neurotoxicity through the ER stress, triggering an apoptosis cascade. J. Transl. Med. 14:78.

5. Mori, K., Obara, Y., Moriya, T., Inatomi, S., Nakahata, N. (2011) Effects of Hericium erinaceus on amyloid β(25-35) peptide-induced learning and memory deficits in mice. Biomed. Res. 32(1):67-72.

6. Mori K, Inatomi S, Ouchi K, Azumi Y, Tuchida T. (2009) Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: a double-blind placebo-controlled clinical trial. Phytother Res. 23(3):367-72.

Lion’s mane lets neurons grow

19.02.2018  /  Scienceandmore  /  Category: Human Biology

Lion’s mane (scientifically Hericium erinaceus) is an edible mushroom that has been used in traditional Chinese medicine for a long time. In recent years, this white, globular-shaped and rotund mushroom has been investigated for its beneficial effects on humans, especially for its neuron growth promoting effects in the brain.

Could it be that lion’s mane has an actual effect on neuron growth, or is it just another disappointing “miracle drug” and temporary hype?

brain mycelium

Biochemical analysis of lion’s mane mushroom found a wide variety of bioactive compounds, but two compounds in particular caught the attention of researchers: hericenones and erinacines. Both compounds have been shown to induce Nerve Growth Factors (NGFs) biosynthesis in nerve cells. NGFs activate cell differentiation and promote growth of neurons, as well as re-myelination of neurons. Myelin is an essential component of neurons and crucial for their function (1).

Investigations in cell cultures showed increased expression of genes that are associated with NGF synthesis upon administration of several erinacines from lion’s mane mushrooms. It was found that these compounds potentiate NGF-induced outgrowth from neurons. This added to the perception that lion’s mane mushroom affects survival and differentiation in nerve cells and displays anti-dementia activity. Therefore, intake of lion’s mane mushroom could potentially reduce the risk of developing neurodegenerative diseases (2).

In a study with rats, erinacine administration resulted in an upregulation of NGF in two brain areas, the locus caeruleus and the hippocampus. These brain areas are usually affected in patients with dementia and Alzheimer’s disease. In accordance with these results, erinacine administration in mice that exhibit symptoms equal to Alzheimer’s and Parkinson’s disease ameliorated the symptoms of both diseases (2,3,4).

Mice with impaired learning and memory that were fed lion’s mane mushrooms performed better in a memory test compared to mice that were not given the mushroom. The mice also regained a sense of curiosity and spend more time exploring novel objects. These results indicate that lion’s mane mushroom administration improves cognitive impairments and could be utilised in the treatment of cognitive dysfunctions such as Alzheimer’s disease (5).

These results are promising, but, in fact, results obtained in the mouse model do not necessarily translate to humans. Fortunately, the effects of lion’s mane mushroom have also been studied in humans.

In a 16 weeks investigation with 30 Japanese men and women between the age of 50 to 80, who exhibited mild cognitive impairment, lion’s mane administration substantially improved their cognitive function. The men and women were tested at weeks 8, 12 and 16 and showed significantly higher scores in cognitive function tests than the control group. Crucially, the cognitive function increased with the duration of lion’s mane mushroom intake. The differences to the control group were greatest at week 16. During the investigation, the subjects were given 250 mg of lion’s mane mushroom daily. However, the beneficial effects decreased after the administration of lion’s mane mushroom was discontinued. The researchers thus concluded that a continuous intake is necessary to maintain the beneficial effects on cognitive functions. The researchers speculated that the promotion of NGF synthesis by compounds in lion’s mane could contribute to the prevention or alleviation of Alzheimer’s disease (6).

An important point that should not be disregarded is the palatability of lion’s mane mushroom. Ingestion of the mushroom itself does not present a health risk even after long-term consumption. However, some people have reported mild troubles with digestion but not to the point where intake has to be discontinued (6).

Overall, the research results are promising, and lion’s mane could contribute to the prevention or at least mitigation of cognitive impairment diseases. With increasing age, everybody will eventually suffer from cognitive impairment in some sort. Maintaining cognitive faculties would enhance the personal quality of life as well as the community’s quality of life.

Another very interesting area for research would be the impact of lion’s mane mushroom on healthy individuals. Would the mushroom-derived promotion of NGF synthesis actually improve cognitive functions? It is hard to speculate on the impact and further investigations are necessary to draw conclusions.

If you enjoyed this text and would like to read a version with more scientific details, click here.

References

1. Lai PL, Naidu M, Sabaratnam V, Wong KH, David RP, Kuppusamy UR, Abdullah N, Malek SN. (2013) Neurotrophic properties of the Lion’s mane medicinal mushroom, Hericium erinaceus (Higher Basidiomycetes) from Malaysia. Int J Med Mushrooms. 15(6):539-54.

2. Zhang, C.-C., Cao, C.-Y., Kubo, M., Harada, K., Yan, X.-T., Fukuyama, Y., & Gao, J.-M. (2017). Chemical Constituents from Hericium erinaceus Promote Neuronal Survival and Potentiate Neurite Outgrowth via the TrkA/Erk1/2 Pathway. International Journal of Molecular Sciences, 18(8), 1659.

3. Tsai-Teng, T., Chin-Chu, C., Li-Ya, L., Wan-Ping, C., Chung-Kuang, L., Chien-Chang, S., Chi-Ying, H.F., Chien-Chih, C., Shiao, Y.J. (2016) Erinacine A-enriched Hericium erinaceus mycelium ameliorates Alzheimer’s disease-related pathologies in APPswe/PS1dE9 transgenic mice. J. Biomed. Sci. 23(1):49.

4. Kuo, H.C., Lu, C.C., Shen, C.H., Tung, S.Y., Hsieh, M.C., Lee, K.C., Lee, L.Y., Chen, C.C., Teng, C.C., Huang, W.S., et al. (2016) Hericium erinaceus mycelium and its isolated erinacine A protection from MPTP-induced neurotoxicity through the ER stress, triggering an apoptosis cascade. J. Transl. Med. 14:78.

5. Mori, K., Obara, Y., Moriya, T., Inatomi, S., Nakahata, N. (2011) Effects of Hericium erinaceus on amyloid β(25-35) peptide-induced learning and memory deficits in mice. Biomed. Res. 32(1):67-72.

6. Mori K, Inatomi S, Ouchi K, Azumi Y, Tuchida T. (2009) Improving effects of the mushroom Yamabushitake (Hericium erinaceus) on mild cognitive impairment: a double-blind placebo-controlled clinical trial. Phytother Res. 23(3):367-72.

Combining black soldier fly meal and

house fly larvae meal for a superior fish feed

09.12.2017  /  Scienceandmore  /  Category: Animal Biology

Black soldier fly (BSF) and house fly (HF) have been established for the production of fish feed, and are approved for this purpose by EU legislation since July 2017. The larvae stage of both insects is mainly used since they are high in crude protein. The utilisation of black soldier fly larvae (BSFL) and house fly larvae (HFL) meal as replacement for fishmeal in fish feed has been investigated in several fish species and showed promising results.

Amino Acids

The nutrient content of BSFL and HFL has been shown to vary depending on their rearing substrate, but in general, they consist of 40 % to 60 % crude protein. Even though the larvae’s nutrient content can vary, their amino acid (AA) profiles stay constant. It is also important that the AA profile of fish feed is adjusted to the specific fish species and their nutritional needs. The fish species that are cultivated in aquacultures in the EU are mainly carnivorous and omnivorous, such as salmon and rainbow trout. They evolved with fish as significant nutrient source, and their metabolisms adapted to fish. Therefore, it is important that the AA profile of their feed matches the one of fishmeal. The AA profile of both BSFL and HFL is well balanced and, with some exceptions, relatively close to the one of fishmeal. However, their AA profiles could be optimised, which potentially would result in improved growth and development of fish in aquaculture when these meals are used as feeds. In order to achieve an optimisation, a combination of BSFL and HFL meal in equal amounts could compensate for lower amounts of particular amino acids in one of the meals. The AA profile of BSFL meal, HFL meal, and fishmeal are stated in table 1 (1).

Table 1: Amino acid composition (g/16 g nitrogen) of black soldier fly larvaemeal (BSFLM), house fly larvae meal (FHL), fishmeal, and a calculated combination of BSFLM and HFLM to equal parts.

The low amounts of the essential AAs cysteine and tryptophan in BSFL could be compensated by the higher amounts in HFL and a combination would match the fishmeal proportion much closer. The high amounts of the non-essential AAs aspartic acid, proline and glycin in BSFL could compensate the lower amounts in HFL. Additionally, the proportions of the essential AAs valin, phenylalanine and tyrosine are higher in both insect species compared to fishmeal. However, both BSFL and HFL have lower amounts of lysine and threonine. These two AA could be supplemented to bring the AA profile of insect meal to the level of fishmeal. The other AA are similar in content compared to fishmeal (1,2).

The amino acid profile of soy, another substantial component of fish feed, is fairly similar to the one of fishmeal, too (1,2). This suggests that BSFL or HFL meal could possibly substitute for soy or fishmeal, or both. A reduction of soy and/or fishmeal in fish feed would decrease the environmental and ecological impact of these feed materials.

Calcium and phosphorous

BSFL are generally rich in calcium, whereas house fly larvae are very low (7.6 % and 0.5 % of dry mass). Here again, a combination of both insect species could compensate the lack in one species and raise the amount of calcium to fish meal levels (4.3 % of dry mass) (1,2). This, however, is of secondary concern since some fish species have been shown to obtain calcium directly from water (3). Phosphorous levels are low in both species, and an addition of phosphorous could potentially be required (1,2).

Fatty acids

Analyses of BSFL and HFL found that their lipid contents and fatty acid profile highly depend on their rearing substrate. Generally, the lipid content of BSFL is between 24 % and 49 %; and for HFL 9 % up to 26 %.

When BSFL and HFL were reared on cow manure, their fatty acid composition showed high levels of saturated and mono-unsaturated fatty acids, as well as low levels of omega-3 fatty acids, such as EPA and DHA. When fish offal was added to the cow manure, the content of beneficial omega-3 fatty acid in BSFL increased rapidly. Similarly, HFL that were reared on plant based substrate were low in omega-3 fatty acids (4,5).

The utilisation of BSFL and HFL as fish meal replacement in fish feed could therefore result in an alteration of the fatty acid profile in fish. Due to the inability of fish to produce omega-3 fatty acids themselves, they depend on the feed source for these fatty acids. It would be beneficial for fish performance, as well as for the consumer who eat these fish, if their feed would contain a higher amount of omega-3 fatty acids. Ultimately, fish are regarded as a source of omega-3 fatty acids by consumers. It was implicated that a diet with a low omega-6 to omega-3 fatty acid ratio (n-6:n-3 ratio), i.e. higher amounts of omega-3 fatty acids, leads to reduced inflammation and potentially improved prevention of cardiovascular heart disease (6).

The process of providing high amounts of omega-3 fatty acids to fish via larvae is complicated and not solved thus far. It has been suggested to feed larvae fish offal, microalgae and phytoplankton as omega-3 fatty acid sources. This, however, would be uneconomic since these materials could be fed to fish directly by mixing them in the fish feed (7). However, a specific process that is used in other livestock could be adapted. Here, the animals are fed a certain diet before their slaughter in order influence their fat content and fatty acid profile. Similarly, the fish rearing process could be separated in two stages. During the first stage, when the fish grow and develop rapidly, higher amounts of insect meal and insect oil instead of fishmeal and fish oil could be provided. During the second stage, before the fish are caught, higher amounts of fishmeal in the fish feed would increase their omega-3 fatty acid content. Ultimately, the aim is to achieve a high content of omega-3 fatty acids in fish for the consumer (4).

Overall, a combination of BSFL meal and HFL meal in fish feed could be superior to BSFL meal or HFL meal alone in terms of fish growth and development. However, future investigations are necessary to evaluate this approach.

References

1. Makkar, H.P.S., Tran, G., Heuzé, V., Ankers, P. (2014) State-of-the-art on use of insects as animal feed. Animal Feed Science and Technology, 197, 1-33.

2. Tran, G., Heuzé, V., Makkar, H.P.S. (2015) Inserts in fish diets. Animal Frontiers 5(2): 37-44.

3. Simkiss, K. (1974) Calcium metabolism of fish in relation to aging. In Aging of Fish (Ed. by Begenal, T.B., pp. 1-12. Unwin Brothers, Woking.

4. Henry, M., Gasco, L., Piccolo, G., Fountoulaki, E. (2015) Review on the use of insects in the diet of farmed fish: Past and future. Animal Feed Science and Technology, 203:1-22.

5.  Hussein, M., Pillai, V. V., Goddard, J. M., Park, H. G., Kothapalli, K. S., Ross, D. A., et al. (2017) Sustainable production of housefly (Musca domestica) larvae as a protein-rich feed ingredient by utilizing cattle manure. PLoS ONE, 12(2), e0171708.

6. Simopoulos A.P. (2002) The importance of the ratio of omega-6/omega-3 essential fatty acids. Biomed Pharmacother. 2002 Oct;56(8):365-79.

7. Norambuena, F., Hermon, K., Skrzypczyk, V., Emery, J. A., Sharon, Y., Beard, A., & Turchini, G. M. (2015) Algae in Fish Feed: Performances and Fatty Acid Metabolism in Juvenile Atlantic Salmon. PLoS ONE, 10(4), e0124042.

House fly larvae as fish feed in the EU

03.12.2017  /  Scienceandmore  /  Category: Animal Biology

The house fly (HF) (scientifically Musca domestica) is another insect that can be used to convert organic wastes into high protein animal feed.

Mature house flies are greyish in colour, covered in hair, and around 6 to 7 mm long. In general, they live 15 to 25 days. Four to 20 days after copulation, female HFs lay around 500 eggs spread across a couple of days, often into moist substrate such as manure or garbage heaps. Whitish larvae hatch from these eggs within eight to 20 hours after ovipositon (egg deposition). House fly larvae (HFL) immediately start to feed on the present organic material, and require four to 30 days to complete their larval stage and enter pupation, depending on temperature and nutrient availability. Pre-pupal larvae are approximately three to nine mm in length and weigh around 13 mg (1,2).

800px-House_fly-for blog

Pros and Cons of house flies for animal feed production

An advantage of HF is that females lay a large amount of eggs; approximately 500 eggs in the wild and more than 2000 eggs in the controlled environment of the lab. Accompanied by the completion of their larval stage within four days under optimal conditions, HFs seem to be suited for a rapid production of larvae for animal feed production. Similar to BSF, the pre-pupa larval stage is commonly utilised for animal feed production.

HFL can grow on a wide range of organic substrates, including nutrient-poor cow manure, suggesting that they are relatively frugal. This characteristic could be used to turn organic wastes or low-quality substrates into high quality protein for animal feed, as well as nutrient rich fertilisers. HFL also require only small amounts of substrate for feeding, partly due to their fast life cycle. Around 1500 larvae have been reared on around 450 g of fresh manure.

In many studies, animal manure has been used as substrate for HFL. Interestingly, investigations showed that HFL feed on microbes that can be found in great numbers on manure. It has been hypothesised that the actual feed for HFL are microbes and not so much the manure itself (2,3). This, however, could relativise the utilisation of HFL for fish feed production in the EU due to the restrictions for substrates according to EU legislation. Approved substrates could be wheat bran for example. This substrate, however, would potentially not host enough microbes to effectively nourish HFL. Eventually, further investigations are needed to confirm this hypothesis.

The migration behaviour of HFL for pupation could be used for self-collection, similar as it has been proposed for BSFL. However, opinions differ on this topic, since it has been found that HFL grow in manure, pupate directly there and emerged as adult flies without migration to dryer spaces upon pupation. Thus, other collection methods that utilise mesh could be used. Here, the substrate with larvae is spread in a thin layer on the mesh and is subsequently exposed to light. HFL are photophobic and will try to escape the light by migration through the mesh into a container placed below (2,3).

The possession of mouth parts of adult HF and their requirement to feed is regarded as a disadvantage. Adult HF externally liquefy their feed via saliva, which is considered to be the time of possible pathogen transmissions. HF are considered as a pest and carriers of diseases due to this feeding mechanisms, however, no pathogen contamination of fish via HFL meal has been reported (2,4).

HFL also require temperatures between 25 °C and 32 °C, and a high humidity between 60 % and 75 % for optimal growth and development. This could necessitate additional temperature and humidity control, especially during the colder months of the year (1,3).

Hands-on experience found a strong unpleasant odour emerging at the rearing site of HFL. Pests could potentially be attracted to the rearing site when it is situated outside. The odour could also be a nuisance for adjacent neighbours, especially during summer months. Therefore, it could be more suitable to rear HFL in a controlled indoor environment with forced ventilation and gas cleaning.

Nutrient composition of house fly larvae

The nutrient content of HFL varies based on their rearing substrate. Generally, HFL consists of 40 % to 60 % crude protein (which is lower than fishmeal with around 65 % crude protein). The quality of the crude protein is determined by its amino acid (AA) balance. Since fish in aquaculture are mostly omnivorous and carnivorous, and are known to prey on other fish, the AA profile of a fish feed should be oriented towards the profile of fishmeal. Compared to fishmeal, HFL meal has a modestly lower amount of the AAs isoleucine, leucine, and lysine. It has often been suggested to supplement the AAs that are low in concentration in order to bring the AA profile of insect meal up to par with the one of fishmeal. This approach, however, was objected to and no addition of AA has also been proposed (2). Eventually, investigations in different fish species, accompanied by economic calculations, would be necessary to clarify if an AA supplementation is appropriate or even needed.

The lipid content of HFL is also dependent on their rearing substrate, but is generally between 9 % to 26 %. It has been found that more than half (around 57 %) of the HFL oil of larvae reared on cow manure consists of monounsaturated fatty acids; saturated fatty acids form the second largest amount (around 38 %). This HFL oil is low in polyunsaturated fatty acids (4 %), specifically in omega-3 fatty acids (less than 1%). This could be problematic for fish in aquaculture due to their inability to synthesise essential fatty acids like omega-3 fatty acids. The fatty acid profile of BSFL has already been indicated to affect its utilisation in certain fish species. Therefore, it has been suggested to add omega-3 fatty acids by ways of algae for example (2). This approach, however, is questionable.

The phosphorus content in HFL is high (nine to 24 g per kg dry mass) and similar to the one of BSF. However, HFL contain significantly less calcium than BSFL (three to eight g per kg dry mass). Overall, phosphorous and calcium levels are lower than in fishmeal (but higher than in soy). Calcium could be added to HFL meal to improve the calcium:phosphorous ratio. This, however, seems to depend on the fish species the HFL meal is intended for. Several fish species have been shown to obtain calcium directly from water and do not depend on calcium intake from their feed (3,4,5).

Photo by Jeremy Cai on Unsplash-for blog

House fly larvae meal in fish feed

Similar to BSFL, only few investigations have been conducted on the use of HFL as fish feed, and even fewer specifically in fish species that are reared in the EU.

In a 25 days trial, meal from HFL that were cultivated on hen manure could replace 100 % of fishmeal (30 % dietary inclusion) in the diet of common carp without detrimental effects on the digestibility of the fish feed (6).

During a nine weeks trial in rainbow trout, replacement of 25 % of fishmeal with HF pupae meal (larvae were reared on cow manure) resulted in reduced growth of trout. This, however, is stated with the caveat that the control group consumed more calories than the replacement diet group, due to a calculation error made during the diet formulation, that could have contributed to the differences in feed conversion between groups. The lipid content in the fillet of trout fed with HF pupae meal was slightly lower than the one of fishmeal-fed trout. However, the fatty acid profile of HF pupae meal-fed trout showed reduced levels of healthy omega-3 fatty acids (7). This result has already been observed in BSFL meal-fed fish, and a strategy of applying a finishing diet for rainbow trout has been suggested.

In other fish species such as Nile tilapia (Oreochromis niloticus) and African catfish (Clarias gariepinus), HFL meal up to a dietary inclusion of 25 %, which represents around 35 % to 100 % replacement of fishmeal according to different studies, resulted in similar fish growth as diets with fishmeal. Here again, the fish were low in omega-3 fatty acids (3,8).

Research on the utilisation of HFL meal in feed for fish that are mainly reared in the EU is still in its early stages. Future investigations could aim to determined how much dietary inclusion of HFL meal is tolerated by these fish species, as well as if defatted HFL meal in the feed affects fish performance, as suggested by findings in BSFL. Here, it was found that when BSFL are reared on a mixture of cow manure and fish offal, instead of cow manure alone, no effects on rainbow trout performance was observed, whereas the sole use of cow manure resulted in BSFL meal that lead to reduced trout growth (9).

References

1. Sanchez-Arroyo, H., Capinera, J.L. (2017) House fly: Musca domestica. [online] Featured Creatures. Available at: http://entnemdept.ufl.edu/creatures/urban/flies/house_fly.HTM [Accessed: 04.11.2017].

2. Hussein, M., Pillai, V. V., Goddard, J. M., Park, H. G., Kothapalli, K. S., Ross, D. A., et al. (2017) Sustainable production of housefly (Musca domestica) larvae as a protein-rich feed ingredient by utilizing cattle manure. PLoS ONE, 12(2), e0171708.

3. Makkar, H.P.S., Tran, G., Heuzé, V., Ankers, P. (2014) State-of-the-art on use of insects as animal feed. Animal Feed Science and Technology, 197, 1-33.

4.NCIPMI (1998) Insect and related pests of man and animals. North Carolina Integrated Pest Management Information. [online] Available at: http://ipm.ncsu.edu/AG369/notes/black_sol-dier_fly.html [Accessed: 05.11.2017]

5. Simkiss, K. (1974) Calcium metabolism of fish in relation to aging. In Aging of Fish (Ed. by Begenal, T.B., pp. 1-12. Unwin Brothers, Woking.

6. Ogunji, J., Pagel, T., Schulz, C., Kloas, W. (2009) Apparent digestibility coefficient of housefly maggot meal (magmeal) for Nile tilapia (Oreochromis niloticus L.) and carp (Cyprinus carpio). Asian Fisheries Science. 22: 1095-1105.

7. St-Hilaire, S., Sheppard, C., Tomberlin, J.K., Irving, S., Newton, L., McGuire, M.A., Mosley, E.E., Hardy, R.W., Sealey, W. (2007) Fly prepupae as a feed stuff for rainbow trout, Oncorhynchus mykiss. J. World Aquacult. Soc. 38:59-67.

8. Tran, G., Heuzé, V., Makkar, H.P.S. (2015) Inserts in fish diets. Animal Frontiers 5(2): 37-44.

9. Henry, M., Gasco, L., Piccolo, G., Fountoulaki, E. (2015) Review on the use of insects in the diet of farmed fish: Past and future. Animal Feed Science and Technology, 203:1-22.

Black soldier fly larvae as fish feed in the EU

09.11.2017  /  Scienceandmore  /  Category: Animal Biology

According to regulation (EU) N° 2017/893, processed animal protein (PAP) from several insect species are approved for the production of feed for animals in aquaculture in the EU. The animals in aquaculture that require ample feed are mainly the following carnivorous and omnivorous fish:

Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), gilt-head seabream (Sparus aurata), European bass (Dicentrarchus labrax), common carp (Cyprinus carpio), and Atlantic bluefin tuna (Thunnus thynnus). In general, a major part of their diet in the wild are other fish and shellfish, but also insects (see previous article).

This article discusses the utilisation of black soldier fly as feed for these fish species. Here, the larval stage shortly before the transition to pupa, i.e. prepupa, is the main development stage that is used for fish feed production, as prepupae contain the highest amounts of protein and fat (egg → larva → pupa → adult fly).

Black Soldier Fly (scientiflcally Hermetia Illucens)

Black soldier flies (BSF) (family Stratiomyidae) are found in tropical and warmer temperate regions. Adult flies are black in colour and of wasp-like shape with a length of approximately 15 to 20 mm. Mature BSF live for approximately 5 to 8 days. During this time they do not take up feed due to their lack of mouth pieces. They solely rely on the storage they built up during their larval stage. The mature female fly can mate after two days and oviposit (laying eggs) quickly after (1). Female BSFs lay more than 500 eggs that makes BSF very interesting in terms of utilisation for the production of animal feed (2). From eggs, whitish black soldier fly larvae (BSFL) hatch that reach an approximate length of 27 mm, width of 6 mm, and weigh of 220 mg as prepupae.

Hermetia_illucens larvae for BLOG

An advantage of BSFL is that they can feed on a wide range of substrates, including food and kitchen scraps, coffee bean pulp, but also other organic wastes such as distillers grains and fish offal, as well as animal manure. A single BSFL can feed on 25 to 500 mg of fresh matter per day, which makes them important decomposers of organic substrates. Due to the quick processing and drying, organic wastes do not tend to emit odour. Subsequently, the residual organic waste could be used as fertiliser since it is still rich in nutrients (1,3). Due to EU legislation, utilisable substrates are restricted and BSFL are not allowed to be reared on manure or food wastes, if they are intended for the production of PAP in animal feed.

In order to optimally rear BSFL, proteins, carbohydrate, fats and a certain structure of the substrate need to be provide. Different ecologically and economically sustainable substrates have been used, such as mixtures that are used for laying hens (mix of maize, wheat, sunflower cake, calcium carbonate, soybean cake, peas, rapeseed cake, rice bran, spelt husks, monocalcium phosphate, soybean oil, sodium chloride, sodium bicarbonate), but also mixtures of cereal processing leftovers (grinding dust, broken pellets and spilled grains), leftovers of distilling processes (dried barley, corn, wheat and sugar syrups), dried sugar beet pulp, and plant compost from tomatoes (4,5,6).

Another advantage of BSFL is their migrating behaviour at the end of their larval stage that can be utilised for collection. The larvae migrate from their humid substrate in order find a dry and protected site for pupation. A self-collection method has been developed by Diener et al. (2011). Here, the larvae climb up a ramp out of the cultivation container and are collected in another container at the end of the ramp (7). However, it has been stated that the utilisation of the migration behaviour does not work as expected, as a uniform migration was not obtained, and a high mortality rate was found due to the artificially high humidity in the substrate. It was concluded that sieving is required for separation of the larvae from their substrate (4).

A disadvantage of BSF is the potentially long period for the larvae to reach their final larval stage. It can last from two weeks up to four months depending on nutrient quality and availability, as well as environmental conditions. For propagation purposes, the subsequent pupal stage can last from 14 days up to 5 months. BSFs and BSFL also require a stable warm and humid environment (between 27 °C and 30 °C, and 50 % to 70 % humidity) that possibly necessitates additional heating and air humidification during cultivation in order to optimise development and growth (1,4,8).

In terms of nutrient content, BSFL contain 40 to 44 % crude protein, which makes them a rich protein source for animal feed. Their fat content can vary greatly and has been shown to depend on the substrate. Oil-rich substrates for example resulted in a fat content of 42 % to 49 %, but also in reduced protein content (1,10).

BSFL are rich in calcium but poor in phosphorus compared to fishmeal (5 % to 8 % of dry matter and 0.6 % to 1.5 % of dry matter, respectively). They have a rather unsuitable calcium:phosphorous ratio for fish feed that, however, could be improved by adding phosphorous. Desired ratios range between 1.1 to 1.4. BSFL have 35 % to 45 % dry matter, which is relatively high and makes it easier to dehydrate them (1,9,10).

Investigations on BSFL as feed for the fish species that are mainly reared in aquaculture in the EU are scarce.

rainbow-trout-2350400_960_720

An 8 weeks investigation in the mainly carnivorous rainbow trout (Oncorhynchus mykiss) showed that meal of BSFL could replace 25 % and 50 % of the fishmeal, representing 16 % and 33 % of the total feed (dietary inclusion), without adverse effects on rainbow trout growth and development compared to fish fed with 29 % fishmeal in their diet. The rainbow trout fillets also did not have differences in sensory quality. This, however, was only observed when BSFL were reared on a substrate that consisted of cow manure and fish offal in equal proportions. When BSFL were reared on cow manure only, replacement of fish meal lead to reduced growth of rainbow trout (10). In a 9 weeks study where 25 % of the fishmeal was replaced with BSFL meal, representing 15 % of the total diet, rainbow trout growth was also not affected. Replacement of 50 % of fishmeal, representing 30 % dietary inclusion, however resulted in reduced growth compared to fish fed with fishmeal (36 % dietary inclusion). Here, BSFL were reared on pig manure (10).

Conversely, in an 8 weeks trial where BSFL were reared on tomato plant compost, which would be in compliance with EU legislation, up to 50 % of fishmeal was replaced by BSFL meal without losses in rainbow trout performance or sensory quality (6). These results suggest that the composition of the substrate for BSFL affects their applicability in rainbow trout feed.

These investigations utilised full fat BSFL meal. Two other studies investigated the utilisation of defatted BSFL meal (by mechanical pressure). In an 11 weeks trial with defatted BSFL meal, where BSFL were grown on plant based substrate according to EU legislation, a replacement of up to 50 % of the fishmeal, which represented 40 % dietary inclusion, resulted in similar survival and growth of rainbow trout compared to the fishmeal control diet. Digestibility of the BSFL diet was found to be very good and no alterations of the intestinal morphology of rainbow trout were observed (11). Similarly, in a 7 weeks trial with BSFL reared on food and kitchen scraps (pasta, spent brewer grains, fruit and vegetable leftovers), the defatted meal was used to replace 46% of the fishmeal, which corresponded to 28 % diet inclusion. No differences were observed in terms of weight gain between the replacement diet and the control diet that utilised fishmeal. Also, no significant differences in taste and odour were found between BSFL meal and fishmeal fed rainbow trout. The fillet of BSFL meal fed fish, however, was a little darker in colour (12). Yet, detrimental effects on the fatty acid profile, specifically on the beneficial fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), were found in rainbow trout when BSFL meal replaced 50 % of fish meal (lipids health indices were also negatively affected). Fatty acid profile differences between control diet and 25 % replacement diet were rather small. It was suggested that the higher amount of fishmeal and therefore fish oil in the 25 % replacement diet provided enough beneficial fatty acids (11).

It could be hypothesised that the fatty acid profile of rainbow trout fed with a 50 % BSFL replacement diet could be improved before butchering by feeding them a finishing diet that contains higher amounts of fishmeal.

In a 15 weeks study with the carnivorous Atlantic salmon (Salmo salar), it was found that a replacement of 25 %, 50 % or 100 % of fishmeal with BSFL meal, representing 5 %, 10 % and 25 % dietary inclusion, performed equally well as the control diet with 20 % fishmeal. Fish of all four groups showed similar growth. The amount of the beneficial fatty acids EPA and DHA was slightly reduced in salmon that were fed with the 50 % and 100 % replacement diet, but not with the 25 % replacement diet. However, fish oil and rapeseed oil were added to all diets, which relativises the fatty acid profile results. Sensory testing of fillets of fish from all four groups yielded no differences. Histological investigations also did not show significant physiological changes. The researchers suggested that the preparation method of BSFL meal could affect performance in fish. When the BSFL meal was highly defatted, salmons showed reduced weight gain with all three replacement diets compared to the control diet that contained 20 % fishmeal (BSFL were reared on human food waste, which would not be approved according to EU legislation) (10,13).

Speculations about the reasons for the observed weight gain differences are hard to make due to the lack of studies in Atlantic salmon.

A 9 weeks investigation in the carnivorous European bass (Dicentrarchus labrax) showed that replacing 20 %, 40 %, and 60 % of fishmeal with BSFL meal in the fish diet, corresponding to dietary inclusion of 6.5 %, 13 % and 19.5 %, did not significantly affect growth and development of the European bass compared to control diet (32 % fishmeal). No palatability issues were observed. This study, however, had a relatively low sampling size of 10 fish per group (14).

In a 10 weeks trial, gilthead seabream (Sparus aurata) were either fed a fishmeal diet with 45 % fishmeal (control diet) or a replacement diet where 10 %, 20 % or 30 % of the fishmeal was substituted by BSFL meal (corresponding to 9.5 %, 19.4 %, and 27.6 % dietary inclusion). Substrate for BSFL mainly consisted of plant based organic wastes. All replacement diets performed worse than the control diet and the replacement diet fed fish showed reduced growth. Palatability of BSFL meal was also found to be reduced. The researchers suggested that the reduced weight gain of gilthead seabream fed with the replacement diets was caused by lower feed consumption due to lower palatability of BSFL meal (15).

Overall, the results of these investigations suggest that BSFL meal can replace fishmeal in parts. The composition of the substrate for BSFL and the fat content of the BSFL meal seem to play crucial roles for the utilisation of the BSFL as fish feed. Research results indicate that plant based substrates and defatting of BSFL meal allow for a higher dietary inclusion without detrimental effects of rainbow trout performance. Atlantic salmon seems to depend much more on a high fat content of the feed for optimal growth and development. European bass appears to manage well with BSFL meal as fishmeal replacement, whereas for gilthead seabream, BSFL meal could be less palatable. It must be noted that the development stages of the fish varied between the mentioned studies. This could be a reason for the different results, since fish at different developmental stages require different diets. In general, the predatory consumption of other fish increases with age. Comprehensive studies across the whole life cycle of fish could shed more light into the applicability of BSFL meal in fish diets.

References

1. Makkar, H.P.S., Tran, G., Heuzé, V., Ankers, P. (2014) State-of-the-art on use of insects as animal feed. Animal Feed Science and Technology. 197:1-33.

2. NCIPMI (1998) Insect and related pests of man and animals. [online] North Carolina Integrated Pest Management Information. Available at: http://ipm.ncsu.edu/AG369/notes/black_sol-dier_fly.html [Accedssed: 02.11.2017].

3. PROteINSECT (2016) Insect Protein – Feed for the Future. [online] Minerva Communications UK Ltd. Available at: https://www.fera.co.uk/media/wysiwyg/our-science/proteinsect-whitepaper-2016.pdf [Accessed: 02.11.2017]

4. Katz (2013) Endbericht zum Forschungsvorhaben „Entwicklung eines Verfahrens zur industriellen Produktion von Präpuppen der Fliege Hermetia illucens zur Futterproteinproduktion. [online] Heretia Futtermittel GbR. Available at: http://www.katzbiotech.de/hermetia/dokumente/Abschlussbericht%20Hermetia%20FuE%20Brandenburg.pdf [Accessed: 03.11.2017]

5. Tschirner, M., Simon, A. (2015) Influence of different growing substrates and processing on the nutrient composition of black soldier fly larvae destined for animal feed. Journal of Insects as Food and Feed. 1(4):249-59.

6. Stamer, A., Wesselss, S., Neidigk, R., Hoerstgen-Schwark, G. (2014) Black Soldier Fly (Hermetia illucens) larvae-meal as an example for a new feed ingredients’ class in aquaculture diets. [Conference paper] Proceedings of the 4th ISOFAR Scientific Conference 2014.

7. Diener, S., Zurbrügg, C., Roa Gutiérrez, F., Nguyen Dang Hong, Morel, A., Koottatep, T., Tockner, K., (2011) Black soldier fly larvae for organic waste treatment – prospects and constraints. [Conference paper] WasteSafe 2011 – 2nd Int. Conf. on Solid Waste Management in the Developing Countries. 13-15 February 2011.

8. Tomberlin, J.K., Adler, P.H., Myers, H.M. (2009) Development of the Black Soldier Fly (Diptera: Stratiomyidae) in Relation to Temperature. Environ Entomol. 38(3):930-4.

9. Tran, G., Heuzé, V., Makkar, H.P.S. (2015) Inserts in fish diets. Animal Frontiers 5(2):37-44.

10. Henry, M., Gasco, L., Piccolo, G., Fountoulaki, E. (2015) Review on the use of insects in the diet of farmed fish: Past and future. Animal Feed Science and Technology. 203:1-22.

11. Renna, M., Schiavone, A., Gai, F., Dabbou, S., Lussiana, C., Malfatto, V., Prearo, M., Capucchio, M.T., Biasato, I., Biasibetti, E., De Marco,M., Brugiapaglia, A., Zoccarato, I., Gasco, L. (2017) Evaluation of the suitability of a partially defatted black soldier fly (Hermetia illucens L.) larvae meal as ingredient for rainbow trout (Oncorhynchus mykiss Walbaum) diets. Journal of Animal Science and Biotechnology. 8, 57.

12. Stadtlander, T., Stamer, A., Buser, A., Wohlfahrt, J., Leiber, F., Sandrock, C. (2017) Hermetia illucens meal as fish meal replacement for rainbow trout on farm. Journal of Insects as Food and Feed. 3(3):165-75.

13. Lock, E.R., Arsiwalla, T., Waagbo, R. (2016) Insect larvae meal as an alternative source of nutrients in the diet of Atlantic salmon (Salmo salar) postsmolt. Aquac Nutr. 22:1202-13.

14. Sánchez López, A. (2015) Potential of pre-pupae meal of the Black Soldier Fly (Hermetia illucens) as fish meal substitute: effect on growth performance and digestibility in European sea bass (Dicentrarchus labrax). Mster thesis. Universitat Politecnia Valencia.

15. Karapanagiotidis, I.T., Daskalopoulou, E., Vogiatzis, I., Rumbos, C., Mente, E., Athanassiou, C.G. (2014) SUBSTITUTION OF FISHMEAL BY FLY Hermetia illucens PREPUPAE MEAL IN THE DIET OF GILTHEAD SEABREAM (Sparus aurata). [Conference Paper] HydroMedit 2014, November 13-15, Volos, Greece.

Music from within the Cell

29.10.2017  /  Scienceandmore  /  Category: Fun Science

Music is and has been a major part of life on earth, and it is not just birds and whales that sing. It has been proposed that humans already sang before we developed language, and that music is closely linked to social contact between humans. Music is typically experienced in groups, part of our evolution since a wide range of cultures invented instruments and songs, and even rooted in our biology (1).

But what if music and life share an even deeper basis? What if music and DNA, the basis of life on earth, share a common principal? And consequently, what would it sound like if DNA and the coded proteins could be translated into music?

Kenshi Hayashi and Nobuo Munakata, two of the first scientists since the discovery of DNA asked and answered the question what DNA sequences could sound like. During the 80s when no computer-assisted analyses tools for DNA sequence analysis existed yet, the two scientists from Tokyo, Japan thought about a way to simplify and facilitate the tedious endeavour of handling DNA sequences. They assigned solmization syllables to the four nucleotides that constitute DNA: “re” for guanine (G), “mi” for cysteine (C), “sol” for thymine (T) and “la” for adenine (A), as well as additional further specifications for G and C- and A and T-rich regions (2) to create the first DNA-based music. Munakata refined this system and later released electronic songs based on nucleotide and amino acid sequences on this web page (www.toshima.ne.jp/~edogiku/index.html). Some of the songs are melodic, such as the “Catalog of Restriction Enzyme” (enzymes that cut DNA strands), while others such as “Coupling Made Easy by RecA-DNA Complex” sound a bit chaotic.

The evolutionary biologist Susumu Ohno attended to the question if there is a common principal to music and DNA. He proposed that the principle of recurrence is the basis for both music and coding DNA sequences. He argued that in the light of evolutionary theory, primordial nucleotide sequences in the form of oligomers existed initially and that genomes evolved from these. Ultimately, genomes as a whole are based on repetition of genes whose coding sequences consist of truncated, extended and base-substituted variances of these primordial oligomers (bases are the differentiating parts of nucleotides). Similarly, music is also based on recurrences of different tones and sound sequences. Ohno developed an elaborate system to translate DNA sequences into music by assigning two consecutive positions in the octave scale to each nucleotide. This assignment was based on the molecular weight of the nucleotides: A and G as purines occupy the lower end of the octave scale, while C and T as pyrimidines occupy the upper end. The big surprise came when Ohno reversed this process and translated Chopin Nocturne Op. 55, No. 1 into a sequence of 160 nucleotides. This sequence very closely resembled a part of the open reading frame (ORF – a DNA sequence that encodes a protein) of a specific enzyme in mice that is involved in the expression of proteins based on DNA (the last exon of the large subunit of the RNA polymerase II) (3-5). Ohno continued his work in this field and translated different sequences into classical music pieces, such as “Music Based on part of an Immunoglobulin Gene” (https://www.youtube.com/watch?v=9Q1EkWtff2I), and “A Song in Praise of Peptide Palindromes” (https://www.youtube.com/watch?v=0RNLG-ol75Q).

The next big technical progress in translating DNA sequences into music was accomplished by David Deamer, a chemist/biochemist, who, similarly to Hayashi and Munakata, initially decided to allocated notes to the different nucleotides: A translated to the musical note ‘A’, C to ‘C’, G to ‘G’, and T to ‘E’. He expressed the 300 nucleotides sequence of an ALU element in the human genome (ALU elements are a family of nucleotide sequences that represent approximately 10 % of the human genome) into an electronic melody. Alongside other songs, the ALU gene song was released on the album “DNA Music / DNA Suite” (excerpts can be found at https://store.cdbaby.com/cd/drdaviddeamer). This initial work was followed by an ingenious and less arbitrary method than just assigning notes to nucleotides. Deamer utilised the light absorption of the four nucleotide bases to translate DNA into music. He measured the absorption of infrared light of different wavelengths by the nucleotides with a spectrophotometer and then translated the spectra into a band of frequencies that fall into the range of human hearing (in Hertz). The data was then converted into musical tones with a synthesiser, where light with a higher wavelength translated to a higher note (6). On this basis, Deamer and the composer Susan Alexjander released the album “Sequencia” with a nice mix of Western and Indian classical music (excerpts can be found at https://store.cdbaby.com/cd/salexjander and https://www.youtube.com/watch?v=VYjmKfsBcPc).

amino acid

Alongside the translation of DNA sequences, the proteins encoded by DNA have also been translated into music. John Dunn and Dr Marry Anne Clark created music according the amino acid characteristics of the protein, where musical parameters were assigned to the different molecular weights, molecular volumes and biochemical categories of amino acids (i.e. hydrophobic amino acids were assigned a lower pitch than hydrophilic ones for example). The secondary structure of the proteins also shaped the music (i.e. α-helices and β-sheets). The team translated the beta-globin (part of the human haemoglobin) and lysozyme C (an enzyme that is part of the immune system) sequences, amongst others, into electronic music with the occasional hint of classical music, and featured them on the album titled “Life Music: Improvisation on Genetic Themes” (songs can be found at whozoo.org/mac/Music/CD.htm), as well as on John Dunn’s homepage (http://algoart.com).

This translation does not only have artistic value but was also used to detect differences or rather similarities of orthologous proteins in different species, as it was done for human haemoglobin and the globin of Tuatara species (reptiles) (orthologous proteins means that proteins in different species share a common ancestral genetic basis but diverged during evolution; however, they retained the same function (8)). The musical similarities in addition to the actual written sequence similarities of both proteins indicate that humans and Tuatara could have had a common ancestor (7).

Linda Long, founder of Molecular Music (www.molecularmusic.com), went a slightly different technical route and translated proteins from herbs and medical plants, as well as human hormones such as the thyroid hormone (which is also a protein) into music according to their secondary structure that she determined by X-ray crystallography. Important parameters were again α-helices and β-sheets that were translated to arpeggios and a series of similar notes, so Long. The songs could be described as relaxing electronic and classical music (excerpts can be found on her homepage).

Several other scientists and artists have since contributed to this field, such as Stuart Mitchell, founder of Your DNA Song Ltd (www.yourdnasong.com), who offers a unique service. Based on personal DNA sequencing data that is done by “23 and Me” for instance, they compose individual music in genres like classical music, Jazz, Rock, as well as contemporary music such as Techno and Hip Hop.

An interesting web-based tool to make you own music based on the secondary structure of proteins was developed by Ram Samudrala and is called “Proteomusic”. It can be found at the Protinfo web server, including instructions on how to use it (http://protinfo.compbio.buffalo.edu/proteomusic/).  Samudrala even released songs himself, where he presents his idea of the sound of protein translation (production of proteins according to RNA) for instance. It is difficult to describe the music genre, but his songs certainly have elements of electronic and rock music.

References

1. Schulkin, J., & Raglan, G. B. (2014) The evolution of music and human social capability. Frontiers in Neuroscience, 8, 292.

2. Hayashi, K, Munakata, N. (1984) Basically musical. Nature 310(5973):96.

3. Ohno, S., Ohno, M. (1986) The all pervasive principle of repetitious recurrence governs not only coding sequence construction but also human endeavor in musical composition. Immunogenetics 24(2):71-8.

4. Ohno, S. (1988) On periodicities governing the construction of genes and proteins. Anim Genet. 19(4):305-16.

5. Ohno, S. (1987) Repetition as the Essence of Life on this Earth: Music and Genes. In: Neth R., Gallo R.C., Greaves M.F., Kabisch H. (eds) Modern Trends in Human Leukemia VII. Haematology and Blood Transfusion / Hämatologie und Bluttransfusion, vol 31. pp: 511-9. Springer, Berlin, Heidelberg.

6. Alexjander, S., Deamer, D. (1999) The infrared frequencies of DNA bases: science and art. IEEE Eng Med Biol Mag. 18(2):74-9.

7. Dunn, J. and Clark, M.A. (2004) Life Music: The Sonification of Proteins. [online] Available at: https://www.leonardo.info/isast/articles/lifemusic.html [Accessed 26.10.2017].

8. Fitch, W.M. (1970) Distinguishing homologous from analogous proteins. Systematic Zoology 19 (2): 99–113.

Insect based feed for animals
in aquaculture 
in the EU

25.10.2017  /  Scienceandmore  /  Category: Animal Biology

Recent changes in EU legislation allow feeding of animals in aquaculture with processed animal protein (PAP) from insects since July 2017. This amendment mainly affects insect meal (dried insects ground to meal) that consists of protein to a big proportion, especially when it is defatted. Oil from insects, as well as fresh or unprocessed dried insects are not included in this restrictions by EU legislation and can be fed to animals in aquaculture, pets, poultry and pigs. Here the question arises, why would insect meal be preferred over fresh and dried insects? Insect meal can be mixed with other feed components such as ground grains and soy to form a mixture of desired composition that is then pressed in pellets for better and more convenient feeding to animals.

Animals in aquaculture are mostly reared by the five EU member states Spain, UK, France, Italy and Greece, who produce around 75 % of the animals in the EU. 294,000 tons of animals in aquaculture were reared by Spain (equals 23.0 % of the EU total, with a worth of approximately €513 million), 212,000 tons by the UK (16.6 %, €995 million), 180,000 tons by France (14.1 %, €627 million), 149,000 tons by Italy (11.6 %, €437 million) and 106,000 tons by Greece (8.3 %, €463 million) (1). Here, the most relevant and important animals are molluscs and fish, and the following 10 species account for around 90 % of the total weight in the EU in descending order:

1) Mediterranean mussel (Mytilus galloprovincialis), 2) Atlantic salmon (Salmo salar), 3) rainbow trout (Oncorhynchus mykiss), 4) blue mussel (Mytilus edulis), 5) gilt-head seabream (Sparus aurata), 6) Pacific oyster (Magallana gigas), 7) European bass (Dicentrarchus labrax), 8) common carp (Cyprinus carpio), 9) Japanese carpet shell (Venerupis philippinarum), and 10) Atlantic bluefin tuna (Thunnus thynnus).

This is stated with the annotation that the EU consists of different countries with different geography, and that the various fish species also have different natural habitats. 95% of the Atlantic salmon is reared in the UK, and 87% of Pacific oyster in France for instance (1). At the same time, other species have wider dissemination. Rainbow trout for example is reared by 17 of the EU member states and the common carp by 13 states as one of their major fish species (2).

salmon

In terms of species-specific feed in the wild, the three molluscs Mediterranean mussel, blue mussel and Pacific oyster consume bacteria, phytoplankton and other small organic matter. In aquaculture, their cultivation does not require additional feed (3-5).

The stated seven fish species are carnivorous or omnivorous and a major part of their diet in the wild are other fish and shellfish, but also insects (6-9).  As of yet, fish in aquaculture have been fed with fishmeal and plant-based feeds, as well as oil from fish and plants. Due to the increasing prices of fishmeal and fish oil, more and more plant-based material from legumes, oil seeds or cereal gluten has been introduced to animal feed. It seems, however, difficult to substitute large amounts of fishmeal and especially fish oil with plant based material. They have disadvantages compared to fishmeal, such as less palatability, anti-nutritional components, high fibre and non-starch polysaccharides content, and a fatty acid and amino acid profile that were proposed to be less suitable than the ones of fishmeal (1).

Insect meal could be a beneficial addition in fish feed and could substitute parts of fishmeal and plant content, since the amino acid profile of insects is more comparable to fishmeal than the one of plants to fishmeal (11). However, depending on the utilised insect species, insect proteins could still be low in the amino acids such as methionine and lysine that potentially would make it necessary to supplement these in animal feeds, specifically for growing animals. This also suggests that insect meal could only partially substitute fishmeal (12,13). The combination of different insect species could compensate the lack of certain amino acids in one of the species. Considering the amino acid profiles of black soldier fly and house fly larvae, they partly complement each other and together they match the profile of fishmeal much closer than the individual ones. The low levels of tryptophan in black soldier fly larvae could be compensated by the higher amounts in house fly larvae for instance.

Fish oil contains higher amounts of omega-3 fatty acids than vegetable oil that are in particular important for carnivorous species such as salmon and trout. The amount of these fatty acids could be insufficient for the fish if the plant content of their feed would be higher (10). The ratio of alpha-linolenic acid (one of the three omega-3 fatty acids) to linoleic acid in insect oils is not as good as in fish oils, but in general better than in vegetable oils. Nevertheless, this is one of the limiting factors for the utilisation of insect meal and insect oil in fish feed, since fish need these fatty acids due to limited metabolic capabilities to synthesis them or due to better growth and development when these fatty acids are provided in their diet (13). However, investigations showed that the fatty acid composition of insects can be modified by modulating the content of their substrate (12,13), and thus potentially adjusted to fit more closely the requirements of a specific fish species.

Fish diets contain relatively low levels of carbohydrates, and the most common carbohydrate would be chitin that is probably digested to a degree by fish. Investigations showed chitinase activity, an enzyme that is involved in chitin digestion, in several fish species. The addition of chitin to fish feed of marine fish has even been suggested to have beneficial effects on these fish. Insects contain low levels of carbohydrates that were estimated to be less than 20 %, and chitin forms the majority of it. However, it is agreed upon that chitin is another limiting factor for the utilisation of insect in fish feed (2014).

Insects are in general relatively low in calcium compared to fish meal, although there are exceptions like the black soldier fly that is high in calcium. Soy is also characterised by low levels of calcium. However, similar to the fatty acid content, calcium content of insects can be affected by the calcium content of their substrate. Nevertheless, addition of calcium could be necessary to ensure optimal development and growth of fish. Phosphorus levels are also relatively low in insects, as well as in soy, compared to fishmeal. An important factor for fish feed is the ratio of calcium to phosphorous and would possibly need adjustment to reach 1.1 to 1.4 as found in fishmeal (13).

According to EU legislation, seven insect species are allowed for the production of animal feed in aquaculture (Regulation (EU) N° 2017/893):

1) black soldier fly (Hermetia illucens), 2) housefly (Musca domestica), 3) mealworm or yellow mealworm (Tenebrio molitor), 4) lesser mealworm or litter beetle (Alphitobius diaperinus), 5) house cricket (Acheta domesticus), 6) tropical house cricket or banded cricket (Gryllodes sigillatus), and 7) Jamaican field cricket (Gryllus assimilis).

These species are regarded as non-pathogenic and do not pose a risk for human, animal or plant health. Furthermore, they do not transmit human, animal or plant pathogens, i.e. are not regarded as vectors, are not protected species or invasive alien species. In fact, they are now classified as „farm insects” and have a similar status as livestock (according to EG 1069/2009 of the new legislation). The new legal status of these seven insects has certain additional consequences and regulation that need to be abided by. For animal feed production purpose, a cultivation of these insects is not allowed on substrate that contains kitchen or food scraps, meat or bone meal, liquid manure or faeces (according to EG 999/2001 and EG 767/2009).

 

Allowed are substrates of:

1) non-animal origin or

2) animal origin that fall within category 3 substances, specifically fish meal, blood products of non-ruminants, Dicalciumphosphate and Tricalciumphosphate, hydrolysed proteins from non-ruminants, hydrolysed proteins of ruminants and their hides, gelatine and collagen of non-ruminants, eggs and egg products, milk and dairy-based substances, colostrum, honey, and rendered fats (amended schedule XIV, chapter I, clause 2, section 5 b and c of the EU 142/2011).

Significantly, high importance was placed on the exclusion of unprocessed products of ruminant origin to prevent potential cross-contamination with prions. Prions were attributed for the catastrophic outbreak of BSE in the 90s. These substrate regulations also apply for insect meal that is imported from non-EU counties into EU countries.

 

Next article: Black soldier fly larvae as fish feed in the EU

References

1. Eurostat (2016) Dive into aquaculture in the EU. [online] Eurostat. Available at: http://ec.europa.eu/eurostat/en/web/products-eurostat-news/-/DDN-20171018-1 [Accessed 19.10.2017].
2. Eurostat and Eumofa (2013) European Commission – Fisheries – 4. Fisheries and aquaculture production [online]. Available at: https://ec.europa.eu/fisheries/4-fisheries-and-aquaculture-production_en [Accessed 20.10.2017].
3. MarLIN (2006) BIOTIC – Biological Traits Information Catalogue. [online] Marine Life Information Network. Plymouth: Marine Biological Association of the United Kingdom. Available at: www.marlin.ac.uk/biotic [Accessed 19.10.2017].
4. Department of Agriculture, Forestry and Fisheries (DAFF) (2017) Mediterranean mussel Mytilus galloprovincialis. [online] Available at: http://www.nda.agric.za/doaDev/sideMenu/fisheries/03_areasofwork/Aquaculture/BIODIVERSITY/M.%20galloprovincialis%20BRBA%2012.12.12.pdf [Accessed 19.10.2017].
5. FAO (2017) Ruditapes philippinarum (Adams & Reeve, 1850). [online] Cultured Aquatic Species Information Programme. Available at: http://www.fao.org/fishery/culturedspecies/Ruditapes_philippinarum/en [Accessed 25.10.2017].
6. Rochard, E. and P. Elie (1994) La macrofaune aquatique de l’estuaire de la Gironde. Contribution au livre blanc de l’Agence de l’Eau Adour Garonne. In État des connaissances sur l’estuaire de la Gironde (ed. by Mauvais, J.-L. and Guillaud, J.-F.), pp 1-56. Agence de l’Eau Adour-Garonne, Éditions Bergeret, Bordeaux, France.
7. Frimodt, C. (1995) Multilingual illustrated guide to the world’s commercial warmwater fish. Fishing News Books, Osney Mead, Oxford, England.
8. Kottelat, M. and Freyhof, J. (2007) Handbook of European freshwater fishes. Publications Kottelat, Cornol and Freyhof, Berlin.
9. ICCAT (2009) Report of the standing committee on research and statistics (SCRS). Madrid, Spain.
10. Scientific, Technical and Economic Committee for Fisheries (STECF) (2014) The Economic Performance of the EU Aquaculture Sector (STECF 14-18) (Ed. Nielsen, R., Motova, A.), pp. 403. Publications Office of the European Union, Luxembourg, EUR XXXX EN, JRC XXXX, xxx pp.
11. PROteINSECT (2016) Insect Protein – Feed for the Future. [online] Minerva Communications UK Ltd. Available at: https://www.fera.co.uk/media/wysiwyg/our-science/proteinsect-whitepaper-2016.pdf [Accessed 19.10.2017].
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