Biomass augmentation through thermochemical pretreatments greatly enhances digestion of switchgrass by Clostridium thermocellum

Background The thermophilic anaerobic bacterium Clostridium thermocellum is a multifunctional ethanol producer, capable of both saccharification and fermentation, that is central to the consolidated bioprocessing (CBP) approach of converting lignocellulosic biomass to ethanol without external enzyme supplementation. Although CBP organisms have evolved efficient machinery for biomass deconstruction, achieving complete solubilization requires targeted approaches, such as pretreatment, to prepare recalcitrant biomass feedstocks for further biological digestion. Here, differences between how C. thermocellum and fungal cellulases respond to senescent switchgrass prepared by four different pretreatment techniques revealed relationships between biomass substrate composition and its digestion by the two biological approaches.