Highly Efficient Utilization of Sugar in Molasses for Butyric Acid Production by Clostridium tyrobutyricum

Molasses, a sugar industry waste product with low cost and high sugar content, can be used as a high-quality carbon source for microbial fermentation. In this study, molasses was pretreated by means of acid–base treatment combined with 0.6% mass fraction of activated carbon in order for its sugar concentration (78.42 g/L) and composition to meet the needs of Clostridium tyrobutyricum fermentation. C. tyrobutyricum was able to produce butyric acid from the sugars of treated molasses by microbial adaptive laboratory evolution. After 120 h of shake flask fermentation, high-performance liquid chromatography and gas chromatography showed that 46.39% of fructose and 32.56% of glucose in molasses after treatment were converted to 31.52 g/L butyric acid by C. tyrobutyricum . The results showed that the two-step process, combined with microbial adaptive laboratory evolution technology used to hydrolyze and reuse sugar, is an adapted method for the utilization of molasses, a by-product of the sugarcane industry.