Abstract
Schizochytrium species is one of the most studied microalgae for production of docosahexaenoic acid (DHA) which is an omega-3 fatty acid with positive effects for human health. However, high cost and low yield in production phase makes optimization of cultivation process inevitable. We focus on the optimization of DHA production using Schizochytrium sp. using different media supplements; glucose, fructose and glycerol as carbon variants, proteose peptone and tryptone as nitrogen variants. The highest biomass (5.61 g/L) and total fatty acid yield (1.74 g/L) were obtained in proteose peptone medium which was used as the alternative nitrogen source instead of yeast extract. The highest DHA yield (0.40 g/L) was achieved with glycerol as the carbon source although it had the second lowest biomass production after ethanol containing medium. Ethanol, as an alternative carbon source and a precursor for acetyl-CoA, increased DHA percentage in total lipid content from 29.94 to 40.04% but decreasing the biomass drastically. Considering different carbon and nitrogen sources during cultivation of Schizochytrium sp. will improve DHA production. Combination of proteose peptone and glycerol as nitrogen and carbon sources, respectively, and addition of ethanol with a proper timing will be useful to have higher DHA yield.
Highlights
Long chain polyunsaturated fatty acids (LC-PUFAs) are known as crucial for human nutrition with their roles in the development of human brain in early stages of life
Schizochytrium sp. was incubated in media varying with carbon and nitrogen sources and O D660 was measured by spectrophotometer in a 6 days period
Tryptone and proteose peptone were used as alternative nitrogen sources instead of yeast extract in the medium
Summary
Long chain polyunsaturated fatty acids (LC-PUFAs) are known as crucial for human nutrition with their roles in the development of human brain in early stages of life. Dietary supplements for humans that are rich in DHA covers a large share of the market and are mostly produced from fish rather than microbial sources (Martins et al 2013). The production of these omega-3 rich oils demands new sources and the efforts in developing microbial production can increase the market share by reducing the prices. PUFA yield depends on environmental conditions such as nitrate starvation, increased salinity changed concentrations of carbon and nitrogen composition and their sources, and variations at light intensity
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