Efficient bioconversion of high-content volatile fatty acids into microbial lipids by Cryptococcus curvatus ATCC 20509

Abstract

The lower utilization ratios of high-content VFAs resulted in less lipid yield by the oleaginous yeast Cryptococcus curvatus ATCC 20509. In this work, increasing the inoculation concentration to OD600=5.1 improved the acetic acid utilization ratio (99.8%) and lipids production (4.63g/L) in mediums with 30g/L of acetic acid. For the higher acetic acid concentration (40g/L), increasing the nitrogen to carbon ratio (0.033) and raising the initial pH (pH=8) was superior over improvement in the inoculate, with the lipid production increased from 1.08g/L to 6.49g/L. Subsequently, mixed VFAs at concentrations of 30g/L and 40g/L were used as the carbon source to simulate waste-derived VFAs. High lipid production (4.82 and 7.45g/L, respectively) was correspondingly achieved with similar high lipid yield (0.187g/g). This study provides an effective strategy to enhance the bioconversion of high-content VFAs into microbial lipids.

Keywords: C. curvatus ATCC 20509; Initial pH; Inoculation concentration; Microbial lipids; VFAs.