Improved resistance against oxidative stress of engineered cellobiose-fermenting Saccharomyces cerevisiae revealed by metabolite profiling

Cellobiose has garnered attention as an alternative carbon source for numerous biotechnological processes because it is produced when lignocellulosic biomass is treated with endo and exo-glucanases. An engineered Saccharomyces cerevisiae (CEL), expressing cellobiose transporter and intracellular beta-glucosidase utilized cellobiose efficiently. As compared to the culture using glucose, the CEL strain grown on cellobiose produced a similar yield of ethanol with slightly reduced growth rate. In this study, concentrations of central metabolites were monitored at mid-log phase with GC/MS to compare cellobiose- and glucose-grown CEL strain. When the CEL strain was grown on cellobiose, intracellular trehalose concentration increased 6-fold as compared with the glucosegrown cells. Interestingly, the higher level of trehalose in cells grown on cellobiose resulted in physiological changes which might be beneficial for biotechnological processes. We observed higher resistance against oxidative stress when cellobiose was used. Oxidative stress is commonly occurred by the byproducts of pretreatment process of lignocellulosic biomass, such as 2-furaldehyde (furfural) and 5-hydroxymethylfurfural (HMF). Our study demonstrated that intracellular metabolite profiling of yeast strains can be employed for linking intracellular concentrations of metabolite with physiological changes of cells upon genetic and environmental perturbations.