Comparative assessment of microbial community of soybean paste prepared with different raw materials

Soybean paste as one of the most extensively used traditional fermented condiments in our daily lives. The quality of soybean paste has been proven to be related to microbial metabolic activities. However, the effect of different raw materials on the microbial diversity of soybean paste under the same incubation conditions remains unclear. For this, we investigated variation of microbial communities in soybean paste manufactured with two different raw materials (Tartary buckwheat flour and wheat flour) analyzed by amplicon sequencing. The results showed that the dominant bacteria in the two soybean pastes were γ-proteobacteria, Cyanobacteria and Bacilli, the dominant fungal were Mucoromycetes, Tremellomycetes, Eurotiomycetes and Saccharomycetes. Bacterial diversity and abundance showed no significant difference in the two soybean pastes; fungal abundance showed no significant difference, whereas fungal diversity differed significantly (P < 0.05). Also, Bacterial abundance correlated positively with amino acid nitrogen (AAN) and total acidity (TA) in flour bean paste, while fungal diversity correlated negatively with AAN and TA in buckwheat bean paste. Collectively, raw materials have a significant effect on the microbial community of soybean paste. Besides, these results could provide valuable reference data for enhancing the quality and safety of soybean paste in manufacture.