Biosynthesis of single cell oils extracted from microbial cultures

Abstract

In recent years, microorganisms have been receiving increased attention as sources of edible lipids, thus they are potential to become a source for producing novel single cell lipids (SCLs). Considerable research has been devoted to techniques for growth, extraction, and purification of high value lipids for their use as biofuels and biosurfactants as well as high-value metabolites for nutrition and health. The performance of SCL can be improved by modifying the fatty acids through transesterification using organic solvents in the availability of strong base or acid catalysts. The purpose of this study was to explore the potential of single cell oils extracted from fungal and algal strains through some preparation procedures, including incubation, oil extraction, esterification, transesterification and emulsification of oil containing microbial biomass indirectly. Transesterification using hexane-isopropanol produced a high fatty acid methyl ester content. The SCL that were extracted from molds (Monascus purpureus, Monilia sitophyla, Aspergillus oryzae, Mucor javanicus, Fusarium oxysporum) and algae (Scenedesmus dimorphus, Chlorella vulgaris and Spirulina fusiformis could produce SCL through direct transesterification by application of heat with a lot of anhydrous methanol and a sodium hydroxide as a catalyst which serves to increase reaction speed and yield. The SCL derived from the  F. oxysporum and M. javanicus were predominated with palmitic acid (41% and 40%), while those were from A. oryzae, M. purpureus and M. sitophyla were predominated with linoleic acid (42%, 36,1% and 36%). The SCL derived from C. vulgaris and S. fusiformis dominated by linolenic acid (24% and 36%, respectively), while that was from S. dimorphus was dominated by linoleic acid (24%). Palmitic and linoleic acids were potentially esterified and transesterified in the manufacturing of methyl ester of fatty acids.