Correlation analysis of microbial communities and precursor substances of ethyl carbamate (EC) during soy sauce fermentation

This study focused on the correlation between microbial communities and precursor substances of ethyl carbamate (EC) during soy sauce fermentation. High-throughput sequencing showed that there were ten dominant bacterial communities in soy sauce fermentation. The dominant fungal communities were Zygosaccharomyces rouxii, Candida versatilis and Candida tropicalis. Weissella, Pediococcus and Lactococcus were the dominant bacteria which had positive correlation with ethanol accumulation, while Acinetobacter, Pseudomonas and Bacillus were negatively correlated with ethanol accumulation. Fungi with the strongest positive correlation with ethanol accumulation were OTU3 and OTU110, which all belong to Zygosaccharomyces rouxii, while Ascomycotina and Aspergillus had the strongest negative correlation with ethanol accumulation. Three bacteria belong to Halobacterium, Acinetobacter and Halomonas, and two fungi belong to Aspergillus and Saccharomyces cerevisiae had the strongest positive correlation with urea accumulation, while Lactococcus and Leuconostoc, and Zygosaccharomyces rouxii had strongest negative correlation with urea accumulation. The main bacteria with positive correlation with citrulline and arginine content were Leuconostoc, Weisiella and Galactococcus, while the bacteria with negative correlation were mainly Acinetobacter, Halomonas and Halobacterium. The fungi with positive correlation with citrulline and arginine content were all mainly Zygosaccharomyces rouxii, while the fungi with negative correlation were mainly Mortierella and Apiotrichum loubieri.