Abstract:Objective Horse milk has a high nutritional value and a unique flavor, which are closely related to its complex microbial composition, and different geographical locations and climates will affect the microbial community structure of horse milk. This study aims to explore the effects of different geographical locations on the microbial community structure in horse milk.Method Metagenomic technology was employed to analyze the microbial diversity of 14 batches of horse milk samples from 3 different regions in northern Xinjiang, and the functional genes were excavated.Result A total of 26 species of microorganisms were identified, belonging to 9 phyla, 14 classes, 25 orders, 28 families, and 45 genera. The dominant species were Lactobacillus helveticus, Acetobacter pasteurianus, Lactobacillus crispatus, and Brettanomyces bruxellensis. There were 11 common genera in the samples from different regions, with the dominant genus being Lactobacillus and the dominant species being L. helveticus, while the relative abundance was different in the samples from different regions. Compared with fresh horse milk, fermented horse milk showed increased relative abundance of Lactobacillus, Acetobacter, Lentilactobacillus, and Brettanomyces, and decreased relative abundance of Streptococcus, Terrisporobacter, Staphylococcus, Enterococcus, Campylobacter, and Klebsiella. The annotation in the KEGG database revealed 23 547 genes, which were involved in carbohydrate metabolism, amino acid metabolism, translation, membrane transport, energy metabolism, nucleotide metabolism, and cofactor and vitamin metabolism. The annotation results with the eggNOG database showed that the bacteria in horse milk contained abundant genes related to replication, recombination and repair, carbohydrate transport and metabolism, amino acid transport and metabolism, etc. Glucoside hydrolase genes (12 155 454) and glycosyl transferase genes (1 130 442) were abundant in horse milk bacteria, followed by auxiliary activity genes (184 638) and carbohydrate esterase genes (465 134).Conclusion Different geographical locations can affect the microbial community structure in horse milk, and the microbial community structure varies among different types of horse milk.
