Co-utilization of multiple lignocellulose-derived sugars and inhibitors by the robust mutant Kluyveromyces marxianus through adaptive laboratory evolution

Abstract

Economical bioethanol production using lignocellulosic biomass requires robust microorganisms with strong inhibitor resistance, thermotolerance and multi-carbons uptake. To obtain a desirable microbial platform, Kluyveromyces marxianus 1727 was employed to conduct adaptive laboratory evolution (ALE) in mixed inhibitors of increasing concentrations about 90 days, a robust mutant K. marxianus 1727-5 was gained with enhanced inhibitors tolerance and improved utilization of the inhibitors. The uptake rate of high concentration acetate, formate, furfural, vanillin increased by 25%, 32%, 65% and 48%, respectively. Besides, K. marxianus 1727-5 had great competence in utilizing glucose, xylose, arabinose, acetate, formate, furfural, vanillin in non-detoxified hydrolysates simultaneously at 40 °C with 80% sugars used and produced 14.2 g/L ethanol with the yield 0.46 g/g. It’s a breakthrough in lignocellulosic biomass bioconversion which multiple carbon sources were used with high product yield. To find the relevant mechanism, genome resequencing was carried and then SNPs correlate to the phenotypes were revealed with potential targets for gene modification in K. marxianus. This study provides a new choice for the construction of robust strains to facilitate utilization of lignocellulosic biomass.