Effect of Bacillus subtilis Y61 inoculation on bacterial community and metabolic profile of sichuan paocai fermentation

Bacillus species have been found in Sichuan paocai (SCP); however, their role in SCP remains to be elucidated. In this study, the effect of Bacillus subtilis Y61 inoculation on physicochemical properties, bacterial community and metabolic profile of SCP fermented for seven days was investigated. The results revealed that inoculation with B. subtilis Y61 could accelerate the decrease in pH and reduce the salinity of SCP, promote the growth of lactic acid bacteria (LAB), such as Lactobacillus and Lactococcus, and inhibit the growth of some opportunistic pathogens. Additionally, forty differential metabolites were observed in the ripe SCP, among which the contents of linalool, γ-terpinene, lactic acid, oxalic acid and most amino acids, were significantly higher in B. subtilis Y61-inoculated SCP fermentation compared to those in the spontaneously fermented SCP. These findings suggest that the inoculated fermentation of B. subtilis Y61 can enhance the quality and safety of SCP as well as can shorten fermentation time.