Microbial Communities and Physicochemical Characteristics of Traditional Dajiang and Sufu in North China Revealed by High-Throughput Sequencing of 16S rRNA

Abstract

The process of soybean fermentation has been practiced for more than 3,000 years. Although Dajiang and Sufu are two popular fermented soybean products consumed in North China, limited information is available regarding their microbial composition. Hence, the current study sought to investigate, and compare, the physicochemical indicators and microbial communities of traditional Dajiang and Sufu. Results showed that the titratable acidity (TA), and salinity, as well as the lactic acid, and malic acid contents were significantly higher in Sufu samples compared to Dajiang. Furthermore, Sufu samples contain abundant sucrose and fructose, while the acetic acid content was lower in Sufu compared to Dajiang samples. Moreover, the predominant bacterial phyla in Dajiang and Sufu samples were Firmicutes and Proteobacteria, while the major genera comprise Bacillus, Lactobacillus, Tetragenococcus, and Weissella. Moreover, Dajiang samples also contained abundant Pseudomonas, and Brevundimonas spp., while Halomonas, Staphylococcus, Lysinibacillus, Enterobacter, Streptococcus, Acinetobacter, and Halanaerobium spp. were abundant in Sufu samples. At the species level, Bacillus velezensis, Tetragenococcus halophilus, Lactobacillus rennini, Weissella cibaria, Weissella viridescens, Pseudomonas brenneri, and Lactobacillus acidipiscis represented the major species in Dajiang, while Halomonas sp., Staphylococcus equorum, and Halanaerobium praevalens were the predominant species in Sufu. Acetic acid and sucrose were found to be the primary major physicochemical factor influencing the bacterial communities in Dajiang and Sufu, respectively. Furthermore, Bacillus subtilis is strongly correlated with lactic acid levels, L. acidipiscis is positively correlated with acetic acid levels, while Staphylococcus sciuri and S. equorum are strongly, and positively, correlated with malic acid. Following analysis of carbohydrate and amino acid metabolism in all samples, cysteine and methionine metabolism, as well as fatty acid biosynthesis-related genes are upregulated in Dajiang compared to Sufu samples. However, such as the Staphylococcus, W. viridescens, and P. brenneri, as potentially foodborne pathogens, existed in Dajang and Sufu samples. Cumulatively, these results suggested that Dajiang and Sufu have unique bacterial communities that influence their specific characteristics. Hence, the current study provides insights into the microbial community composition in Dajiang and Sufu samples, which may facilitate the isolation of functional bacterial species suitable for Dajiang and Sufu production, thus improving their production efficiency.

Effect of Bacillus subtilis and Lactobacillus plantarum on solid‐state fermentation of soybean meal

“…The BS had the lowest content (0.03%), implying that the addition of B. subtilis could reduce the relative content of Staphylococcus in the FSBM. The same phenomenon was also observed for soybean fermentation by other Bacillus strain 32 …”

“…The same phenomenon was also observed for soybean fermentation by other Bacillus strain. 32 During the fermentation process, Bacillus sp. was detected to be the main bacteria on days 1 and 4.…”

Physiochemical and taste characteristics of traditional Chinese fermented food sufu

“…As shown in Figure 1C, the pH value showed a significant increasing trend during the pre‐fermentation. This phenomenon may be caused by some alkaline substances that produced by microbial growth consuming carbon and nitrogen sources from tofu (Liang et al, 2021; Xu et al, 2020). During curing stage, pH presented a sharp decline (S4–S5), followed by a continuous increase between S6 and S7, which was consistent with the previous research results (Yang et al, 2021).…”

Decarboxylase activity of the non-starter lactic acid bacterium Loigolactobacillus rennini gives crack defects in Gouda cheese through the production of γ-aminobutyric acid

“…Moreover, given their co-occurrence in the Gouda cheeses and brines, they might display synergetic growth. Indeed, both species have been found together in spontaneously fermented, salted soybean products ( 56 , 57 ) and fermented fish sushi ( 58 ), despite the relatively rare detection of Loil. rennini in fermented foods.…”