Dual-omics strategy for selecting optimal fermentation strains in traditional koumiss production

Koumiss is a fermented mare's milk beverage with a long history. However, due to the current lack of specialized starters, the product quality is unstable. Therefore, we used dual-omics combined with pure culture technology to screen out strains with excellent fermentation performance for koumiss. The results showed that: (1) The dominant species in koumiss were mainly <i>Lactobacillus</i> and <i>Lactococcus</i>, and metabolites such as arachidonic acid and ascorbic acid were significantly enriched in koumiss. (2) There was a significant correlation between specific microbial species and metabolites. (3) Through preliminary screening using experiments such as milk-based curdling experiments and acid resistance tests, and then rescreening through fermentation tests, five strains with excellent fermentation characteristics were screened out. They are <i>Lacticaseibacillus paracasei</i> SXM-5, <i>Lactobacillus kefianofaciens</i> MGE42-8, <i>Lactobacillus helveticus</i> CFS12-11-1, <i>Saccharomyces cerevisiae</i> PFD-2, and <i>Kluyveromyces marxianus</i> PYM-1. The screened strains supply microbial resources for koumiss products and boost the development of milk beverages.