Complementary effect of combined bacterial-chemical pretreatment to promote enzymatic digestibility of lignocellulose biomass

Chemical pretreatment partially modified the structure of lignocellulose to enhance saccharification, leaving unaltered factors to limit further hydrolysis. To overcome these limitations, a biostrategy involving co-pretreatment combining bacteria with a chemical process was developed. A significant complementary effect was observed in specific co-pretreatments, e.g., ligninolytic bacteria enhanced acid pretreatment and saccharolytic bacteria enhanced alkaline pretreatment. Specifically, the ligninolytic bacterium Pandoraea sp. B-6 selectively removed the acidolysis-caused residual lignin and enhanced sugar release by 40.9% to 772.0 mg g(-1) compared with that of acid-treated rice straw. After most of the lignin was removed, sugar release from alkali-treated RS was further improved by 31.8% to 820.2 mg g(-1) via the saccharolytic bacterium Acinetobacter sp. B-2 through decrystallization. In the complementary mechanism, the active sites produced by chemical cleavage facilitated the bioprocess and further enhanced saccharification. This complementary mechanism provides a novel foundation for designing a rational combination pretreatment.