Characterization of bacterial community and flavor differences of different types of Douchi

Abstract

According to the appearance and technology, traditional fermented Douchi can be divided into dried Douchi and wet Douchi. However, there are few reports on the difference of bacterial community structure between them or the influence of bacterial community on product flavor. In this study, high‐throughput sequencing technology and electronic nose were used to measure the bacterial diversity and flavor of 40 Douchi samples, and the correlation between them was explored by multivariate statistical means combined with COG database. Results showed that the cumulative average relative abundance of Firmicutes and Proteobacteria in the samples was as high as 95.93%, and the former was the core bacteria phylum. On the whole, the dominant bacteria in Douchi were Bacillus (50.67%), Staphylococcus (14.07%), Enterococcus (2.54%), Proteus (1.61%), Brevibacillus (1.46%), Providencia (1.26%), Weissella (1.24%), and Ureibacillus (1.19%). LEfSe analysis indicated that Bacillus can be used as a biomarker in dried fermented soybeans. Meanwhile, dried samples contained more intensive aromatic substances, but were significantly lower in W6S (selectivity to hydrogen) and W3S (methane‐aliph) compared with the wet samples. Aneurinibacillus and Brevibacillus were helpful to the formation of aromatic flavor in Douchi, but Vagococcus and Corynebacterium were the opposite. Gene and microbial phenotypic prediction showed that microorganisms in dried Douchi use protein more efficiently, while in wet Douchi, microbial energy metabolism was more vigorous. The pathogenic potential of microorganisms in dried samples was higher than that in wet. This study can sound the alarm for improving the safety of home‐brewed Douchi and provide guidance for the subsequent screening of strains that enhance the flavor of fermented soybeans.

Correlation between physicochemical properties, flavor characteristics and microbial community structure in Dushan shrimp sour paste

“…The relative abundance of Vagococcus in samples XS2, XS3, and XS4 are 22.26%, 32.58%, and 19.65%, respectively. The Vagococcus can produce energy necessary for fermentation, thereby promoting the process ( Wang, Xiang, Zhang, Hou, & Guo, 2021 ).…”

Dynamic Changes in Microbial Communities and Physicochemical Characteristics During Fermentation of Non-post Fermented Shuidouchi

“…Chen et al found that Bacillus , Bacteroides , and Lactobacillus were the main genera in Shuidouchi with post-fermentation from the different regions in China ( 9 ). Wang et al found that the dominant bacteria were Bacillus , Staphylococcus , Enterococcus , Proteus , Brevibacillus , Providencia , Weissella , and Ureibacillus in wet and dry Enshi Douchi, and Aneurinibacillus also appeared in certain samples ( 36 ). The dominant bacteria in bacterial Douchi from Gansu province in China were Bacillus and Ignatzschineria , and Aneurinibacillus was also found in some samples ( 11 ).…”

Research progress on the fibrinolytic enzymes produced from traditional fermented foods

“…Research has shown that dry Douchi and wet Douchi differ greatly in microflora and richness. In fact, dry Douchi samples were associated with higher pathogenicity than wet Douchi which may be caused by different microbial interactions during fermentation (Wang et al, 2021 ). Moreover, traditional fermented shrimp paste, which is a popular seasoning in Asian countries derived by mixing silver shrimp with salt, has been shown to have strong thrombolytic activity.…”