Research on the Correlation Between Microbial Communities and Physicochemical Indexes of Pixian Broad-bean Paste During Post-fermentation Stage

The evolvement rule and diversity of microbial communities during the post-fermentation of traditionnal Pixian broad-bean paste (PXBP) were analyzed, which the α-diversity and β-diversity of the microbial communities were determined by high-throughput sequencing technology. Moreover, the correlation between core microorganisms and physicochemical indexes was carried out according to partial least squares regression (PLSR) and Pearson correlation coefficient. The results show that the levels of salt and amino acid nitrogen have no obvious change during post-fermentation stage. The values of pH, moisture content and color parameter slowly declined, meanwhile the amounts of total acid and soluble nitrogen risen. Additionally, the content of reducing sugar reached the maximum value when fermentation time lasted until the fourth month. The richness of bacterial community showed a dynamic trend, and the diversity of bacterial community kept stable, except for the ninth month. The richness and diversity of fungal community increased continually at all the post-fermentation processing of PXBP. Nine core microorganisms were positively correlated with moisture content, color parameter and pH, and negatively correlated with the concentrations of total acid, reducing sugar, amino acid nitrogen and soluble nitrogen, however no significant correlation was observed with the salt content.