An high-throughput sequencing approach to the preliminary analysis of bacterial communities associated with changes in amino acid nitrogen, organic acid and reducing sugar contents during soy sauce fermentation

Soy sauce is a traditional fermented soy food for enhancing the umami taste in Asian cuisines. In this study, 16S rRNA gene throughput sequencing analysis showed the bacterial communities and the changes in soy sauce during fermentation. Weissella, Bacillus and Lactococcus were the most abundant at genus level. The uncultured bacterium Weissella and Lactococcus had relatively high abundance at species level. Alpha diversity analysis indicated the bacterial community diversity increased at fermentation initiation, while decreased as fermentation progressed. Based on beta-diversity analysis, four clusters including cluster I (time point A-F), cluster II (G,H), cluster III (I,J) and cluster IV(K) were distinctly separated, indicating the fermentation time significantly affected bacterial community diversity. Also, close associations were found between the bacterial communities in soy sauce and its amino acid nitrogen, organic acid and reducing sugar contents during fermentation. Therefore, it will provide important information for optimization of the soy sauce production process.