Isolation and molecular identification of probiotic yeast strains from horse milk.

Aram Moeni; Shahrad Mohseni Tavakoli; Arash Tazike; Seyed Masoud Hashemi Karoie; Arian  Ghasemi

doi:10.5455/EJMID.20250528111619

Abstract
Background: Probiotics, comprising beneficial bacteria and yeasts, are vital for human health through their roles in digestion and maintaining microbial balance in the gastrointestinal tract.
Objective: This study assessed the probiotic potential of yeast strains isolated from mare’s milk of Dokhon and Turkmen breeds in Golestan Province, Iran.
Methods: Sixteen raw milk samples were collected during spring 2022. Following enrichment, 11 yeast strains were isolated. In vitro probiotic screening included:
Acid tolerance: Exposure to pH 3.0 for 1, 2, and 3 hours.
Bile salt resistance: Viability assessment in bile salt-containing media. Strains fulfilling both criteria underwent molecular identification.
Results: Only 5/11 strains (A3 Dokhon, Á3 Dokhon, A8 Turkmen, Á8 Turkmen, A1 Turkmen) survived pH 3.0 at all timepoints. 10/11 strains tolerated bile salts, retaining viable counts. Five strains (A3 Dokhon, Á3 Dokhon, A8 Turkmen, Á8 Turkmen, A1 Turkmen) demonstrated dual resistance to gastric (acid) and intestinal (bile salt) conditions. Conclusion: Mare’s milk from Dokhon and Turkmen breeds harbors indigenous yeasts with robust probiotic traits. The five identified strains show promise as probiotic candidates, warranting further investigation into their taxonomic identity and functional properties.

Key words: yeast, probiotics, horse milk,Turkmen