Bioconversion of Volatile Fatty Acids into Lipids by the Oleaginous Yeast Apiotrichum Porosum DSM27194

Volatile fatty acids (VFA) derived from waste organics provide economical feedstocks for fuels and oleochemicals production. In this study, the valorization of VFA into microbial lipids by the oleaginous yeast Apiotrichum porosum DSM27194 was investigated. A. porosum DSM 27194 was able to assimilate different VFA mixtures containing acetic, propionic and butyric acid at different ratios for lipid production. By using a two-stage automated fed-batch fermentation strategy with glucose as initial carbon source and VFA mixtures as both carbon source and buffering agent, a dry cell mass concentration of 26.5 g/L with lipid content of 36.2% was achieved with the VFA ratio of 6:1:1 (acetic acid:propionic acid:butyric acid). Fatty acid composition profiles indicated that the lipid derived from VFA is better suited for biodiesel production compared to glucose as carbon source. Moreover, corn stover hydrolysate containing VFA was applied as raw feedstock. Excitingly, A. porosum DSM 27194 could consume all kinds of carbon source within the hydrolysate fast and simultaneously resulting in 28.0 g/L of dry cell mass containing 44.3% of lipid. This study provides a promising oleaginous yeast chassis of A. porosum DSM 27194 and an economical fermentation strategy of two-stage automated fed-batch fermentation for microbial lipid production from low-value VFA derived feedstocks.