Production of Lactic Acid from Wheat Straw Hydrolysates

Abstract

Present research work is aimed at the production of lactic acid from wheat straw (WS), a lignocellulosic waste biomass. Grinded WS (0.5mm) and non-grinded WS were subjected to delignification followed by cellulose separation. Saccharification of cellulose was done by recombinant cellulases and compared with two different thermochemical treatments. The separated cellulose from grinded WS when subjected to enzymatic saccharification, using different enzyme loading ratios, which gave 2.39 mg/ml glucose (119.16±0.35 mg/g) in 48hrs. The cellulose obtained was also subjected to dilute acid hydrolysis at 121°C, with a sugar yield of 10.03 mg/ml and a yield of 0.32g/L lactic acid in 72hrs upon fermentation by Bacillus sonorenesis DGS15 at 50°C. The third pretreatment method was modified acid hydrolysis of delignified biomass, obtained from the first pretreatment at 60°C, 80°C and 121°C. Maximum yield of total reducing sugar and lactic acid of 0.528g/L was obtained from acid treatment of wheat straw at 121°C with overall yield of 0.014g/g and productivity of 0.0073g/L/h.