Integrated microbiomic and metabolomic to reveal characterization of microbial community and flavor differences of Douchi with different salt concentrations

Abstract By utilizing 16S high-throughput sequencing, untargeted metabolomes and GC–MS analysis, this study explored the differences in microbial populations, metabolites and volatile components of douchi fermented under different salinity. Alpha diversity analysis indicated that the bacterial community diversity of CT, ce, RF, and TP groups was significantly greater than that ofQP (p < 0.05). The most DAMs were found in “Phenylalanine metabolism”, “Tyrosine metabolism” “Arginine and proline metabolism” and “Glycolysis/Gluconeogenesis” pathways. In QP versus TP group, Bacillus showed a positive correlation with 6 volatile compounds and a negative correlation with 14 volatile compounds, such as Hexanoic acid, 3-methyl-2-butenyl ester and Methyl 5-hydroxynicotinate, etc. This correlation pattern shows an opposite trend in Tetragenococcus. In YF versus TP group, Tetragenococcus negatively correlated with 20 volatile compounds, such as Benzoic acid, 4-amino-, methyl ester, Benzeneacetic acid, (4-methoxyphenyl)methyl ester, etc. This research provides a theoretical basis for exploring a low-salt fermentation process for douchi, improving the traditional Yangjiang douchi production method, and developing a healthy low-salt douchi product.