The responses of fermentation characteristics and microbial community structure and co-occurrence network to molasses and Lacticaseibacillus casei additions during anaerobic fermentation of Caragana korshinskii

In this study, Caragana korshinskii (C. korshinskii) was fermented with or without molasses (M), Lacticaseibacillus casei (LC), and molasses + L. casei (MLC) for 14 and 56 days. M, LC, and MLC enhanced the contents of lactic acid, acetic acid, 1,2-propanediol, water-soluble carbohydrates, and true protein (P < 0.01) and decreased the pH (P < 0.01) and the contents of butyric acid, ethanol, 2,3-butanediod, free amino acid and ammonium nitrogen (P < 0.01). The control sample exhibited increased Enterobacter, Pantoea, and Clostridium abundance and a decreased Weissella and Lactobacillus abundance compared with that in samples treated M, LC, and MLC. Enterobacter, Clostridium, and Pantoae richness negatively correlated (P < 0.01) with that of Lactobacillus, with correlation values of −0.54, −0.61, and −0.69, respectively. In contrast, positive correlations (P < 0.01) were observed between Enterobacter and Pantoae during fermentation (R = 0.45). Fermentation products during anaerobic fermentation strongly correlated (P < 0.01) with microbial communities, especially Enterobacter, Clostridium, Lactobacillus, and Weissella. Molasses and L. casei additions presented a high abundance of carbohydrate and amino acid metabolism relative to the control group. In conclusion, the combination of Illumina MiSeq sequencing and high-performance liquid chromatography during anaerobic C. korshinskii fermentation can provide a new microbial community composition and fermentation quality information for the application of M, LC, and MLC as food fermentation agents.