Simultaneous enhancement of lignin-derived inhibitor tolerance and lipid accumulation of oleaginous yeast Trichosporon cutaneum by adaptive evolution

Abstract

Inhibitory compounds should be removed from the pretreated lignocellulose feedstock before fermentative production of microbial lipid by oleaginous yeast. Biodetoxification effectively degrades furan aldehydes and weak organic acids, but is less efficient against complex and various lignin-derived phenolic aldehydes. Residual phenolics in lignocellulose hydrolysates require a tolerant fermentation strain. This study adopted the long-term adaptive evolution combined with centrifugal enrichment in corn stover hydrolysate to simultaneously improve the phenolic inhibitors tolerance and lipid synthesis of Trichosporon cutaneum. The obtained mutant T. cutaneum MS28 showed significant improved performances of phenolic aldehydes tolerance and lipid accumulation. The final cellulosic lipid production of T. cutaneum MS28 utilizing corn stover reached 33.8 ± 0.1 g/L, approximately 6-fold higher than that of the starting strain. Transcriptional analysis suggested that T. cutaneum MS28 had more active lignocellulose-derived sugars metabolism and lipid synthesis shunts. The intracellular contents of lipid synthesis precursors including NADPH and acetyl-CoA increased 1.7–3.0 folds. This adaptive evolution in lignocellulose hydrolysate combined with centrifugal enrichment is an efficient tool to targeted enhancement of inhibitors tolerance and cellulosic lipid production of oleaginous yeast.