Efficient hydrolysis of corncob residue through cellulolytic enzymes from Trichoderma strain G26 and l-lactic acid preparation with the hydrolysate

Abstract To prepare fermentable hydrolysate from corncob residue (CCR), Trichoderma strain G26 was cultured on medium containing CCR for production of cellulolytic enzymes through solid-state fermentation (SSF), resulting in 71.3 IU/g (FPA), 136.2 IU/g (CMCase), 85.1 IU/g (β-glucosidase) and 11,344 IU/g (xylanase), respectively. Through a three-stage saccharification strategy, CCR was hydrolyzed by the enzymatic solution (6.5 FPU/ml) into fermentable hydrolysate containing 60.1 g/l glucose (81.2% cellulose was converted at solid loading of 12.5%), 21.4% higher than that by the one-stage method. And then the hydrolysate was used to produce l -lactic acid by a previous screened strain Bacillus coagulans ZX25 in the submerged fermentation. 52.0 g/l l -lactic acid was obtained after fermentation for 44 h, with 86.5% glucose being converted to l -lactic acid. The results indicate that the strains and the hydrolysis strategy are promising for commercial production of l -lactic acid from CCR and other biomass.