Efficient production of l-lactic acid using co-feeding strategy based on cane molasses/glucose carbon sources

• A co-feeding strategy was developed for lactate production on cane molasses source.
• Co-feeding fermentation provided good productivity (2.1 g/L h) and yield (0.88 g/g).
• High l-lactic acid concentration (168.3 g/L) was obtained after the fermentation.

l-Lactic acid is an important platform chemical, which ought to be produced under cost control to meet its huge demand. Cane molasses, a waste from sugar manufacturing processes, is hopeful to be utilized as a cheap carbon source for l-lactic acid fermentation. Considering that cane molasses contains nutrients and hazardous substances, efficient production of l-lactic acid was developed by using a co-feeding strategy based on the utilization of cane molasses/glucose carbon sources. Based on the medium optimization with response surface method, 168.3 g/L l-lactic acid was obtained by a Bacillus coagulans strain H-1 after 78 h fed-batch fermentation, with a productivity of 2.1 g/L h and a yield of 0.88 g/g. Since cane molasses is a feasible carbon source, the co-feeding fermentation might be a promising alternative for the economical production of l-lactic acid.