Isolation and characterization of probiotic yeasts from traditional fermented horsemeat products in Xinjiang: functional evaluation and potential application

Traditional fermented horsemeat and horsemeat sausages in Xinjiang are rich in microbial resources, mainly including lactic acid bacteria and yeasts. Although the probiotic effects of lactic acid bacteria have been widely studied, there is relatively little research on the probiotic properties of yeasts, which limits their application in functional food development. This study isolated 44 yeast strains from traditional fermented horsemeat products in Xinjiang, and 16 strains exhibiting strong tolerance to temperature, acidic pH, simulated gastrointestinal fluids, and high bile salt solution were screened. Molecular identification revealed that these strains belonged to Candida zeylanoides (C-5, C-8, C-13, C-15, C-21, C-22, C-24, R-8), Candida parapsilosis (R-10, R-12, R-14, R-19, R-20), Candida metapsilosis (R-18), and Rhodotorula alborubescens (R-6, R-11). Several strains demonstrated significantly higher cell surface hydrophobicity, auto-aggregation, and co-aggregation with pathogenic bacteria than the control strain Saccharomyces boulardii CNCM I-745, indicating strong intestinal adhesion and antagonistic potential. All strains have high antioxidant activity (> 60%) and certain cholesterol-lowering ability. Furthermore, extracellular metabolites from select strains exhibited antibacterial activity and potential glucose-lowering effects. Specifically, C. zeylanoides C-8 inhibited α-glucosidase by 54.14%, and C-8 inhibited angiotensin-converting enzyme (ACE) by 37.05%. Hemolysis assays confirmed that all strains were non-hemolytic, suggesting good biosafety. These findings highlight the multi-functional probiotic potential of yeast strains from traditional fermented horsemeat products and provide a scientific basis for their development as novel functional food ingredients.