Fermentative Production Of DHA Using Alanine Industrial Waste As Nitrogen Source

Docosahexaenic Acid(DHA)is one of the Omega -3 polyunsaturated fatty acids, which has important biological and physiological functions. Therefore, DHA has been widely used in health care food and assistant therapeutic products, and more and more attention has been paid on the production and preparation process of DHA. However, the traditional way to obtain DHA was unable to meet the needs of the market. As a result, new emphasis has been placed on the development of new DHA sources, which should not only be stable and secure but also for low cost production. Schizochytrium sp. is a promising microorganism in producing DHA as it poses the characteristics of fast growth rate and high content of DHA. Yeast extract is the conventional nitrogen source for DHA production by microalgae, while the production cost is very high. In this study, we attempt to develop a method for producing DHA from alanine industrial waste as nitrogen source to improve the fermentation level, reduce the production cost of DHA to provide new ideas.The results showed that when the alanine industrial waste was used as a single nitrogen source, biomass decreased to 10.21g/L, DHA production dropped to 1.1g / L after 72 hours of fermentation which have lost half of the production. Single factor method was used to optimize the fermentation conditions. The optimized culture medium were diluted alanine industrial waste (150×), 20g/L seawater, 80g/L glucose, 0.4g/L yeast powder, inoculation amount of 14%. Thebiomass production increased to 10.75 g/L, oil content increased to 8.18g/L, DHA production increased to 1.5g/L.The culture media were further optimized by response surface method. The concentration of glucose was 62.17 g / L, the dilution ratio of alanine mother liquor was 178.01, the concentration of cofactor was 0.53 g / L and the inoculation amount was 10.75%. Under the condition of culture, the biomass increased to 14.48 g / L, the oil yield increased to 11.60 g / L, and the yield of DHA increased to 1.98 g / L. DHA yield was 1.8 times comparing with the results before optimization,which was 94.3% under conventional culture conditions.