Characterization of a Potential Probiotic Strain in Koumiss

Abstract

Koumiss is a traditional fermented dairy product in Inner Mongolia pastoral areas, which is deeply loved by the local people; however, there has been little research on the characteristics of probiotics. This study comprehensively explored the properties of potential probiotics in koumiss, combining in vitro assays and whole-genome sequencing. The biochemical identification and phylogenetic tree results showed that the branches of this strain were close to Lacticaseibacillus paracasei, indicating that the strain was L. paracasei. The agar diffusion assay showed that the strain could effectively inhibit the growth of pathogenic bacteria. We have also identified the CHAP structural domain at the genomic level, which may be associated with the antibacterial activity of this strain. The strain was well tolerated in a simulated gastrointestinal environment, growing well at pH = 2.5, 0.3% bile salts, and 5% NaCl while exhibiting hydrophobicity, aggregation, and antioxidant properties. In vitro experiments and genome, levels showed that resistance (resistance genes) to the antibiotics used in this study was not present in this strain. In addition, we did not observe toxic effects in acute oral administration in mice, and no virulence genes were identified at the genomic level. Therefore, the strain has the potential for probiotic development.