d-(−)-Lactic acid production from cellobiose and cellulose by Lactobacillus lactis mutant RM2-2Electronic supplementary information (ESI) available: Additional experimental information. See DOI: 10.1039/b925975a4

• Main Authors: Singhvi, Mamta, Joshi, Dipti, Adsul, Mukund, Varma, Anjani, Gokhale, Digambar
• Format: Article
• Language: English
• ISSN: 1463-9262; 1463-9270
• DOI: 10.1039/b925975a

Lactobacillus lactis mutant RM2-24 utilizes cellobiose efficiently, converting it into d -(−)-lactic acid. Cellobiose-degrading enzyme activities were determined for whole cells, cell extracts and disrupted cells. Aryl-β-glucosidase activity was detected in whole cells and disrupted cells, suggesting that these activities are confined to the cells. The mutant produced 80 g l −1 of lactic acid from 100 g l −1 of cellobiose with 1.66 g l −1 h −1 productivity. Production of d -lactic acid from different cellulose samples was also studied. The cellulose samples at high concentration (10%) were hydrolyzed by cellulase enzyme preparation (10 FPU g −1 cellulose) derived from Penicillium janthinellum mutant EU1 generated in our own laboratory. We obtained a maximum 72% hydrolysis, yielding glucose and cellobiose as the main end products. Lactic acid was produced from these cellulose samples by simultaneous saccharification and fermentation (SSF) in a media containing a cellulase enzyme preparation derived from Penicillium janthinellum mutant EU1 and cellobiose utilizing Lactobacillus lactis mutant RM2-24. A maximum lactic acid concentration of 73 g l −1 was produced from a concentration of 100 g l −1 of bagasse-derived cellulose, the highest productivity and yield being 1.52 g l −1 h −1 and 0.73 g g −1 , respectively. Considering that bagasse is a waste material available in abundance, we propose to use this biomass to produce cellulose and then sugars, which can be fermented to valuable products such as ethanol and lactic acid. Simultaneous saccharification and fermentation (SSF) of cellulosic substrates to d -lactic acid using EU1 cellulases and Lactobacillus lactis mutant RM2-24. The SSF was carried out in screw-cap flasks at 42 °C with shaking at 150 rpm.