Using tobacco waste extract in pre-culture medium to improve xylose utilization for L-lactic acid production from cellulosic waste by Rhizopus oryzae

The aim of this work was to study the high-titer L-lactic acid production from cellulosic waste using Rhizopus oryzae. The tobacco waste water-extract (TWE) added with 5 g/L glucose and 0.1 g/L vitamin C was optimized as pre-culture medium for R. oryzae. Results found that compared to traditional pre-culture medium, it improved xylose consumption rate up to 2.12-fold and enhanced L-lactic acid yield up to 1.73-fold. The highest L-lactic acid concentration achieved was 173.5 g/L, corresponding to volumetric productivity of 1.45 g/L h and yield of 0.860 g/g total reducing sugar in fed-batch fermentation. This process achieves efficient production of polymer-grade L-lactic acid from cellulosic feedstocks, lowers the cost of fungal cell pre-culture and provides a novel way for re-utilization of tobacco waste. (C) 2016 Elsevier Ltd. All rights reserved.