Overproduction of fungal endo-β-1,4-glucanase leads to characteristic lignocellulose modification for considerably enhanced biomass enzymatic saccharification and bioethanol production in transgenic rice straw

Brassinosteroid overproduction improves lignocellulose quantity and quality to maximize bioethanol yield under green-like biomass process in transgenic poplar

“…Compared to the raw materials, the biomass residues obtained from Na 2 S + Na 2 CO 3 pretreatment exhibited rougher surface in both PtoDET2 transgenic poplar and WT ( Fig. 7a), consistent with the previous reports of the rough biomass residues effective for cellulase enzyme loading and digestion [15,17,18,[42][43][44][45]. Using the Congored staining approach established recently [43], we measured cellulose accessibility, which was the direct parameter of cellulase enzyme attack on cellulose surface.…”

“…7a), consistent with the previous reports of the rough biomass residues effective for cellulase enzyme loading and digestion [15,17,18,[42][43][44][45]. Using the Congored staining approach established recently [43], we measured cellulose accessibility, which was the direct parameter of cellulase enzyme attack on cellulose surface. Despite the similar Congo-red staining areas in raw materials of both transgenic lines and WT, the pretreated residues of PtoDET2-OE lines showed significantly (P < 0.01) increased cellulose accessibility than that of WT, with the increased rate of 12-16%, while the decreased rate of 5-6% in the PtoDET2-KO lines (Fig.…”

“…6a, b). Previous studies show that GH9 genes encoded glycoside hydrolase enzymes play important roles in reducing cellulose CrI and DP [18,19,[41][42][43]. We found that transcript levels of two representative PtoGH9s were significantly increased in the PtoDET2-OE lines relative to WT (Additional file 1: Fig.…”

“…Although lignocellulose features could largely affect biomass enzymatic saccharification for bioethanol production as described above, it has been recently shown that biomass porosity and cellulose accessibility of the pretreated residues are the finalized determinant of biomass enzymatic hydrolysis for bioethanol production [15,17,18,[42][43][44][45]. Given that the Na 2 S + Na 2 CO 3 pretreatment is superior to other pretreatments for higher sugar and bioethanol yields in this study, the residues of Na 2 S + Na 2 CO 3 pretreatment were used for subsequent enzyme accessibility measurement.…”

“…Since biomass porosity has been defined to account for cellulase enzyme loading and access to cellulose microfibrils [15,17,18,[42][43][44][45], we also detected biomass porosity of the pretreated residues including surface area and average pore diameter. By comparison, the biomass porosity of PtoDET2-OE lines remained significantly raised than that of the WT at P < 0.01 level, whereas the PtoDET2-KO lines showed markedly reduced biomass porosity (Fig.…”