Biomass saccharification of bioenergy crops enhanced by selective soybean proteins for distinct cellulosic ethanol and lactic acid conversions with high Cd2+ adsorption

As crop straws provide enormous lignocellulose resources convertible for renewable biofuels and valuable bioproducts, an efficient biomass saccharification is thus considered as the critical step for biochemical conversion. Although plant proteins have been applied as active biosurfactants for blocking lignin interaction with lignocellulose-degradation enzymes, little is yet reported about their distinct roles from different plant sources in entire lignocellulose process. In this study, we examined that the co-supplies of soybean seed and leaf proteins could consistently enhance enzymatic saccharification of diverse lignocelluloses substrates from physical and chemical pretreatments with mature straws in three representative bioenergy crops (rice, corn, Miscanthus ). By performing yeast fermentation with enzymatic hydrates, the seed protein samples showed the bioethanol yields increased by 25 %-38 %, whereas the leaf protein samples had the bioethanol ones reduced by 31 %-48 %. However, both seed and leaf protein supplies improved the Lactobacillus paracasei fermentations for lactic acid yields raised by 11 %-61 %. Furthermore, the lignocellulose residues retained from ethanol and lactic acid fermentations were ultimately characterized as active biosorbents for cadmium (Cd 2+ ) adsorption, but only leaf protein samples showed significantly increased adsorptive capacities. Notably, this study attempted to sort out the mechanisms about how the seed and leaf protein supplies could significantly enhance biomass enzymatic saccharifications for either consistently improved lactic acid conversions or contrastively affected bioethanol fermentations, thereby providing a green-like strategy selective for the optimal bioethanol and lactic acid production and heavy metal adsorption with zero-biomass release. • Soybean seed and leaf proteins consistently enhance biomass saccharification. • A contrastive impact on ethanol fermentation from seed and leaf protein supplies. • Both seed and leaf protein supplies consequently enhance lactic acid fermentation. • Full residue of leaf protein sample is unique as desired biosorbent for Cd 2+ adsorption. • A selective strategy for cascading enhanced hexose, ethanol and lactic acid yields.