Fungal combined with ammoniation pretreatment to promote enzymatic hydrolysis of corn stover

A novel pretreatment approach that combined Pleurotus ostreatus treatment and ammoniation was proposed to reduce the intensity of chemical pretreatment and improve enzymatic saccharification. In this study, corn stover was pretreated with P. ostreatus, ammonium carbonate, or a combination of both. The results indicated that the highest sugar yield of 374.55 mg/g, which was 81.85% higher than that of the raw material, was achieved through fermentation followed by ammonium carbonate pretreatment. This elevated reducing sugar yield was attributed to compositional changes, structural variations in lignin and cellulose, decreased relative crystallinity of cellulose, and increased specific surface area and pore size, which improved cellulase accessibility to cellulose. However, while ammoniation followed by P. ostreatus fermentation increased CMCase activity and inhibited laccase activity, no rise in sugar production was observed. In addition, in P. ostreatus combined with ammonium carbonate pretreatment, ammonium carbonate treatment at approximately room temperature (30 °C) instead of strong alkalis, minimized toxicity and corrosiveness, rendering it a mild and promising method to promote enzymatic hydrolysis.