Biocycle Fermentation Based on Lactic Acid Bacteria and Yeast for the Production of Natural Ethyl Lactate

Ethyl lactate is widely used in food and pharmaceutical industries, but the complexity of the synthesis process, in particular, involving the addition of organic solvents, hinders its application. Here, we report a natural green strategy to produce ethyl lactate by exploiting the synergistic fermentation of lactic acid bacteria and ester-producing microbes using biomass as a substrate. Interestingly, it is worth noting that the conjugate fermentation has a higher ethyl lactate yield (3.05 g/L) compared to the mixed fermentation (1.32 g/L). The ester production capacity was increased by 2.3 times. These entire processes require only the addition of biomass without introducing any organic solvent. In addition, the obtained catalytic esterification system can reuse the ester-producing microbes by simple centrifugation and maintain over seven cycles of catalysis while it retained a high activity. We firmly believe that the results of this study will provide new ideas for achieving sustainable green production of natural ethyl lactate.