Increasing extracellular cellulase activity of the recombinant Saccharomyces cerevisiae by engineering cell wall-related proteins for improved consolidated processing of carbon neutral lignocellulosic biomass

Abstract

Sustainable bioproduction using carbon neutral feedstocks, especially lignocellulosic biomass, has attracted increasing attention due to concern over climate change and carbon reduction. Consolidated bioprocessing (CBP) of lignocellulosic biomass using recombinant yeast of Saccharomyces cerevisiae is a promising strategy for lignocellulosic biorefinery. However, the economic viability is restricted by low enzyme secretion levels. For more efficient CBP, MIG1 spsc01 isolated from the industrial yeast which encodes the glucose repression regulator derivative was overexpressed. Increased extracellular cellobiohydrolase (CBH) activity was observed with unexpectedly decreased cell wall integrity. Further studies revealed that disruption of CWP2, YGP1, and UTH1, which are functionally related to MIG1 spsc01, also enhanced CBH secretion. Subsequently, improved cellulase production was achieved by simultaneous disruption of YGP1 and overexpression of SED5, which remarkably increased extracellular CBH activity of 2.2-fold over the control strain. These results provide a novel strategy to improve the CBP yeast for bioconversion of carbon neutral biomass.