Dual-upgraded biomass saccharification and bioethanol production by cascading peptides interactions with polymers and activating cellulases in bioenergy crops

Crop lignocelluloses represent enormous biomass resources convertible for biofuels and bioproducts, but efficient biomass saccharification is crucially required for large-scale biofuel production. Although plant proteins and chemical surfactants could enhance biomass saccharification, it remains to explore advanced activator for further improving lignocellulose degradation and conversion to biofuels. In this study, soybean protein and its peptides were employed into the mixed-cellulases hydrolyses of distinct lignocellulose substrates from representative bioenergy crops. Significantly, the optimal peptides supply could continuously upgrade the hexoses and bioethanol yields by 20 % and 35 %. Despite the soybean peptides, like plant proteins and Tween-80, could effectively interact with lignin and xylan for unblocking mixed-cellulases incubated, this study found a unique interaction between peptides and cellulose microfibrils to retain the mixed-cellulases more accessible for facilitating lignocellulose hydrolysis, which caused either significantly higher hexoses yield or more improved sugar conversion to bioethanol, compared to soybean protein and Tween-80. Based on all findings achieved, this study finally proposes a novel mechanism model about how green peptides act as both active biosurfactant and enzyme activator for cascading improvements of lignocellulose enzymatic degradation and yeast fermentation, thereby providing a powerful strategy applicable for green-like biomass saccharification and highly-efficient bioethanol production in bioenergy crops.