(29o) Enhanced Butanol Production from Lignocellulose Hydrolysate By Engineered Clostridium Tyrobutyricum with Alleviated Glucose-Mediated Carbon Catabolite Repression

Bioconversion of lignocellulose-derived sugars to chemicals such as n-butanol in industrial fermentation has been limited by glucose-mediated carbon catabolite repression (CCR). Clostridium tyrobutyricum, a Gram-positive anaerobic bacterium, has been engineered as a promising n-butanol producer from sugars. To further improve the utilization of xylose present in the lignocellulosic biomass hydrolysate by C. tyrobutyricum, five genes including xylose transcriptional regulator xylR (CTK_RS10130, CTK_RS07715, CTK_RS13695), bifunctional hpr kinase hprK (CTK_RS08295) and catabolite control protein CcpA (CTK_RS00560) were evaluated for their possible roles and effects on xylose utilization and CCR by knocking out these genes individually or in a combinatorial manner using CRISPR genome engineering technique. In addition, three genes (xylT, xylA, and xylB) encoding a xylose proton‐symporter, a xylose isomerase and a xylulokinase involved in xylose catabolism in C. acetobutylicum were cloned and overexpressed in C. tyrobutyricum to achieve the maximum xylose utilization efficiency for butanol production from lignocellulose sugars.