Efficient delignification of sugarcane bagasse by Fenton oxidation coupled with ultrasound-assisted NaOH for biotransformation from Agaricus sinodeliciosus var. Chaidam

Abstract

Sugarcane bagasse (SCB), a widely available lignocellulosic by-product, could be potentially used in macrofungal bioconversion for high-value bioactive compounds. For macrofungus with poor lignin degradation capacity, its recalcitrant lignin structure blocked the release of fermentable sugars for cell growth. Herein, the main objective was to construct an effective delignification pretreatment strategy for SCB biotransformation and synthesis of bioactive substances by Agaricus sinodeliciosus var. Chaidam. Different pretreatments including chemical (alkali and Fenton oxidation) and ultrasound methods were used to intensify the delignification process. Physico-chemical characteristics of native and pretreated SCB were examined via XRD, XPS, FT-IR and 13C ssNMR to characterize crystallinity index, surface lignin and chemical structure. Lignocellulose-degrading enzymes were also used to assess the ability of the macrofungus to degrade SCB. By comparing morphological structure, chemical composition and fermentation characteristics, a suitable multiple sequential pretreatment method was finally identified. Our findings revealed that Fenton-ultrasound-alkali pre-treatment has an optimum delignification effect on SCB with never-uncovered excellent ability to detoxify harmful substances produced by Fenton oxidation. Under this pretreatment condition, the cellulose content was increased by 106.45%, whereas hemicelluloses and lignin were decreased by 48.34% and 74.15%, respectively. The macrofungal growth, intracellular polysaccharides, total phenols and terpenoids formation were 2.4, 1.46, 1.36 and 1.66 times higher than those of the untreated, respectively. Fermentation kinetic results showed outstanding fit and prediction of macrofungal growth and enzymatic activity secretion on above pretreated SCB. This study shed light on developing a novel pretreatment strategy for low-cost SCB lignocellulose transformation into high-value products.