Effect of Caproicibacterium lactatifermentans inoculation on the microbial succession and flavor formation of pit mud used in Chinese Baijiu fermentation

Caproicibacterium lactatifermentans is a major caproate-producing bacterium in high-quality pit mud and has an impact on the synthesis of fatty acids during Baijiu fermentation. To develop an effective method for cultivating high-quality pit mud, we explored the role of Caproicibacterium lactatifermentans inoculation. The inoculation resulted in a high level of Caproicibacterium lactatifermentans (29.16%) and fortified pit mud produced abundant fatty acids and ethyl esters in short-term usage. Rare microbes, such as Hazenella coriacea, promoted the production of fatty acids. After long-term usage, changes in physicochemical properties led to a decrease in caproate-producing bacterium, namely Clostridium and Caproicibacterium, and an increase in microbes with limited fatty acid biosynthesis capability, including Proteiniphilum, Fastidiosipila, and Caldicoprobacter. These alterations ultimately led to a decrease in fatty acids and ethyl esters. In summary, Caproicibacterium lactatifermentans inoculation exhibited positive outcomes in obtaining high-quality pit mud. However, the maintenance of functional microbes necessitates further investigation.