Development of sustainable society through efficient biotechnological production of optically active L-lactic acid from cellulose-derived sugars

Abstract

Effective utilization of cellulosic biomass as a feedstock for lactic acid production is still problematic due to high cost of saccharifying enzymes combined with feedback inhibition caused by final hydrolysis products, glucose and cellobiose. In this study we demonstrated that Enterococcus mundtii QU 25, a newly isolated lactic acid bacterium, is able to utilize cellobiose efficiently. In batch fermentations, 89.8 g/L of L-lactic acid was produced from 100 g/L cellobiose at yield of 91.3 (%) g/g-consumed sugar. Moreover, this strain capable of utilizing glucose/cellobiose mixture simultaneously for efficient production of L-lactic acid without apparent catabolite repression, thereby allowing complete utilization of all released sugars combined high L-lactic acid production yield.