Simultaneously enhancing microbial biomass formation and lactic acid synthesis in Bacillus coagulans via acetate supplementation

Acid inhibition presents a significant challenge in lactic acid fermentation, highlighting the need for innovative strategies to enhance microbial cell growth under acidic conditions. This study investigated the potential of acetate supplementation in glucose fermentation to simultaneously enhance both microbial biomass and lactic acid production in Bacillus coagulans. By adding 10 g/L acetate to glucose fermentation medium, transcriptional analysis revealed that critical metabolic pathways including acetate assimilation, TCA cycle, glyoxylate shunt, and gluconeogenesis were upregulated. In a pH-controlled 5L bioreactor, the addition of 10 g/L acetate substantially increased glucose consumption, resulting in a 6.7 % reduction in alkali usage, a 17.6 % increase in bacterial biomass, and a 15.3 % increase in lactic acid production. This strategy demonstrates dual industrial advantages-enabling efficient production of nutrient-rich microbial biomass for animal feed applications while simultaneously boosting yield of lactic acid as platform chemical, all through simple metabolic modulation via co-utilization of glucose and acetate.