Efficient production of lactic acid from sugarcane molasses by a newly microbial consortium CEE-DL15

Sugarcane molasses, a waste from sugar manufacturing processes, has promising future to be utilized as a cheap carbon source for lactic acid production. In this study, a newly microbial consortium, CEE-DL15, for the conversion of sugarcane molasses to lactic acid was selected and evaluated. The consortium was screened from cattle stomach content and mainly consisted of Clostridium sensustricto (57.29%), Escherichia (34.22%), and Enterococcus (5.32%). Lactic acid production was explored under the deficiency of sterilization and molasses acidification, with corn steep liquor powder used as organic nitrogen source. In batch fermentations using sugarcane molasses of 350 g/L and corn steep liquor powder of 18.5 g/L without additional nutrients, CEE-DL15 produced 112.34 g/L lactic acid (107.40 g/L L-lactic acid and 4.94 g/L D-lactic acid), with a yield of 0.81 g/g and a maximum productivity of 4.49 g/(L.h), which is the best lactic acid productivity from molasses published so far. Economic analysis indicated that lactic acid fermentation cost was only 448 USD/ton using molasses and corn steep liquor powder, which was only 37.7% of the total cost when compared with glucose as carbon source and MRS medium as nitrogen source. This work demonstrated that the high adaptation to molasses of microbial consortium CEE-DL15 might be a promising alternative for the economical production of lactic acid.