Aquaculture feeds from grain ethanol stillage

This innovative research and development project addresses one of the most important issues in our society: How to provide healthful food to our native population through efficient and sustainable use of our domestic resources. Fish raised through aquaculture can meet the rapidly growing demand for seafood while improving diets. Aquaculture is the fastest growing sector of the world's food production. It is expanding 6 times faster than beef production, 2.6 times faster than egg production and 1.7 times faster than poultry production throughout the world. This is good news because fish can turn feed into body mass much more efficiently than poultry, pork or beef, and they are highly nutritious. The polyunsaturated fatty acids in fish are not found in any other major food group and are essential for brain and nerve development - particularly for children and the elderly.Unfortunately, aquaculture depends heavily on the use of fishmeal to cultivate the species most desired by consumers. In essence, it is necessary to feed fish to fish in order to make food for humans. Conventional aquaculture requires about 4.5 lb of fishmeal to make 1 lb of farmed fish. It is possible to substitute vegetable protein for most of the essential amino acids for fish cultivation, but the nutritionally critical ω3 long-chain polyunsaturated fatty acids (ω3 LC-PUFAs) largely come from fishmeal, which places additional pressures on global marine species and ecosystems. Conventional aquaculture based on fishmeal does not really solve the problem of providing sustainable protein for human consumption. By creating vegetable-based feedstocks that supply long chain (LC) PUFAs, the work proposed here will relieve pressure on native fisheries and increase aquaculture sustainability.Yeast protein comes close to satisfying the essential amino acids for fish. Feeds with high levels of yeast amino acids along with ω3-LCPUFAs could well serve this growing market. One potential feedstock for making yeast-based aquaculture feeds comes from the grain ethanol industry. Some of the largest sources of vegetable protein in the United States - and potentially the largest source of LC-PUFAs - are byproducts from grain ethanol production. In the U.S., byproduct protein from grain ethanol production is currently sold as cattle feed due to its high fiber content, but it is not suitable as aquaculture feed. One low-value fraction, however - soluble organics from distillation bottoms - called "thin stillage solubles" could be ideal for producing yeast that make ω3-LCPUFAs. The proposal presented here would create a bioengineered lipogenic yeast to convert the soluble organics present in thin stillage into high titers of ω3-LCPUFAs. At the same time it would provide an amino acid profile appropriate for salmon aquaculture.Xylome has developed a native lipogenic yeast that will produce large amounts of fatty acids from thin stillage solubles. Moreover, we have created a genetic system for this organism that has enabled us to more than double its productivity and lipid accumulation. Using this system we expect to overexpress some of its native genes in order to increase the production of ω3 fatty acids, and introduce other genes that will convert these into the ω3 long-chain polyunsaturated fatty acids essential for brain development and maintenance. In Phase I of this project, we will demonstrate the feasibility of producing yeast rich in ω3-LCPUFAs from low-value stillage byproducts, and in Phase II we will engineer and scale-up production of yeast for aquaculture feed.Ultimately this work will enable the conversion of low-value byproducts from industrial ethanol production into a high value nutritional supplement for aquaculture production both domestically and abroad. As a result of successful development, consumers will realize a lower cost for domestically farmed fish. Feed producers will realize a major cost savings. Pro