Isopropanol production using engineered Corynebacterium glutamicum from waste rice straw biomass

Abstract

Isopropanol, a well-known biofuel, is a widely used precursor for chemical products that can replace nonrenewable petroleum energy. Here, engineered Corynebacterium glutamicum that can effectively utilize all xylose and glucose in agricultural waste rice straw to produce isopropanol was described. First, codon mutations were introduced into transporters and glycolytic-related genes to decrease the glucose preference of C. glutamicum. A more energetically favorable xylose oxidative pathway was constructed that replaced traditional xylose isomerization pathways, saving twice the number of enzymatic steps. A succinate auxiliary module was incorporated into the tricarboxylic acid cycle (TCA), connecting the xylose-utilized pathway with the isopropanol pathway to maximize xylose orientation towards the product. The final engineered strain successfully consumed 100 % of the xylose from NaOH-pretreated, enzyme-hydrolyzed rice straw and effectively synthesized 4.91 g/L isopropanol. This study showcases the successful conversion of agricultural waste into renewable energy, unveiling new possibilities for advancing biological fermentation technology.