Yogurts from Different Producers in Bole, Xinjiang: Bacterial Diversity and Community Structure and Differences in Metabolite Profile as Revealed by Untargeted Metabolomics

The bacterial diversity and metabolomic characteristics of yogurt from three different producers in Bole, Xinjiang were analyzed by using Illumina sequencing and untargeted metabolomics, and the relationship between them was explored. Bacterial diversity analysis showed that the major bacterial genera in the yogurt samples were Lactobacillus, Klebsiella, Lactococcus, and Acetobacter. Using linear discriminant analysis effect size (LEfSe) and phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt), Lactobacillus, Klebsiella, and Lactococcus were identified as biomarkers, and their functions were predicted. The metabolomic analysis identified a total of 397 metabolites in the positive ion mode and 324 metabolites in the negative ion mode, with lipids and lipid-like substances, organic acids and their derivatives, and organic heterocyclic compounds being the predominant ones. Notably, lipids and lipid-like substances, organic acids and their derivatives were the major differential metabolites, contributing to the flavor of yogurt. The metabolic pathway analysis revealed amino acid metabolism and secondary metabolism to be the main enriched pathways, which aligned partially with the functional prediction results. Integrated microbiomic and metabolomic analyses showed that the genera Lactobacillus, Limosilactobacillus, Lactococcus, and Klebsiella were significantly correlated with some metabolites such as organic acids and their derivatives, as well as lipids and lipid-like substances, indicating that the microbial community affected the nutrients of yogurt through its metabolic activities. This study provides a scientific theoretical basis for the production and quality improvement of Xinjiang yogurt.