Abstract: Corncob pretreated by alkali was used as renewable raw material for L-lactic acid production by Rhizopus oryzae. The processes of separate saccharification and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) were studied. The results showed that the enzymatic hydrolysis performance of washed alkali pretreated corncob was better than that of unwashed alkali pretreated corncob. Water-washing process could enhance the fermentability of alkali pretreated corncob. The washed alkali pretreated corncob hydrolysate with 31.84 g/L glucose and 6.38 g/L xylose was converted to 14.65 g/L of L-lactic acid which was equivalent to a yield of 0.29 g/g dry biomass with SHF process at 40 ℃ for 48 h. In contrast, a higher L-lactic acid yield (0.44 g/g dry biomass) was achieved at 40 ℃ for 36 h, when the substrate concentration of 50 g/L washed alkali pretreated corncob was used in SFF process.

Key words: Rhizopus oryzae, alkali pretreated corncob, L-lactic acid, separate saccharification and fermentation, simultaneous saccharification and fermentation.