New Biotechnological Production of EPA by Pythium irregulare Using Alternative Sustainable Media Obtained from Food Industry By-Products and Waste

Long-chain polyunsaturated fatty acids (LC-PUFAs) have multiple beneficial effects on human health, in particular docosahexaenoic acid (DHA, 22:6, n-3) and eicosapentaenoic acid (EPA, 20:5, n-3). A variety of microorganisms has been used for the commercial production of non-animal-source LC-PUFAs. The oomycetes of the Pythium family are promising EPA producers, and in this work, the optimization of Pythium irregulare growth using food industry by-products and wastes as cheap sources of nutrients was carried out. Sugar cane molasses (SCM), spent brewery yeast (SBY), cheese whey (CW), and expired orange juice (EFJ) were tested. A combination of SBY as a source of nitrogen and EFJ as a source of organic carbon resulted in the best outcome among the other sustainable media ingredients. The optimization of the new medium was conducted through a response surface methodology using EFJ and SBY as factors. The results show a significant positive impact of these factors on biomass productivity (p < 0.005), with an optimized biomass yield of 14.22 g L-1, a lipid yield of 2.23 g L-1, and an EPA concentration of 155 mg L-1.