Correlation analysis between microbial diversity and physicochemical indices of Koumiss

This study examined the influence of change in microbial flora during fermentation on the quality of Koumiss. The microbial diversity of Koumiss samples was analyzed at different fermentation periods using high-throughput sequencing. Also, the physiochemical (protein, fat, ash, moisture, lactose, soluble solids, and energy) and functional (antioxidant activity, cholesterol removal ability, and bacteriostatic ability) indices were estimated. Finally, a correlation analysis was made between the change in microbial flora structure and physicochemical and functional indices. The dominant bacteria phylum was Firmicutes, and the dominant bacteria genus was Lactobacillus. In the early stage of fermentation, the dominant bacteria phylum of fresh mare milk was Actinobacteria, while the dominant bacteria genus was Rothia. Concerning fungal community structure, the dominant phylum was Ascomycota, and the dominant genus was Dekkera. In the early stage of fermentation too, the dominant fungal phylum was Ascomycota, but the dominant genus was Candida. The lactose and energy contents of fresh mare milk were higher, which was consistent with other physiochemical indices. After fermentation, the contents of lactose, soluble solids, and energy decreased, and the contents of protein and fat fluctuated. The functional characteristics of fermented mare milk are remarkable. Besides, it has a strong antibacterial ability. The bacteria that positively correlated with lactose, soluble solids, and energy were Rothia, Streptococcus, Enhydrobacter, and Macrococcus (p<0.05). Also, DPPH hydroxyl free radical capacity and reducing power positively correlated with Pichia (p < 0.05); Hydroxyl radical scavenging ability positively correlated with Yarrowia and Dipodascus (p < 0.05); Energy and lactose negatively correlated with Yarrowia and Dipodascus (p < 0.05).