Molecular evolution mechanism of Candida tropicalis to inhibitory compounds derived from corn stover hydrolysis

This study set out to increase the level of tolerance of Candida tropicalis SHC-03 through stepwise evolution and also to decipher the molecular mechanisms involved in the degradation of inhibitory compounds derived from corn stover hydrolysate. It was observed that the mutant C. tropicalis SHC-03 exhibited an increased rate of fermentation in corn stover hydrolysate-supplemented media and also showed a lower level of ROS accumulation and damages to other subcellular regions as compared to the parent strain. Transcription analysis from this study also revealed up-regulation of 1600 and 1503 as well as 1922 and 1997 down-regulated genes in the mutant and parent strains respectively, among which include genes involved in various pathways required for inhibitory compounds degradation and detoxification. Besides, genomic sequencing revealed mutations in genes that enriched in general functions, nuclear structures, among many others provided various phenotypic and genetic variations in the evolved strain to increase its rate of tolerance to inhibitors. These results suggest that the subsequent introduction of C. tropicalis SHC-03 to corn stover hydrolysate increased its tolerance and resistance abilities towards the inhibitors derived from corn stover hydrolysate. The information from this study will provide alternative ways for the future development of yeast mutants with high tolerance towards inhibitors derived from corn stover hydrolysate.