Study of probiotic potential of yeasts isolated from dairy products, sourdough, and fruit peel

More than four decades after discovering probiotic strains, the food and dairy industries are increasingly seeking to improve their products with these beneficial yeasts. This study aimed to characterize potential Iranian native probiotics and assess the safety of native yeasts probiotics isolated from fermented products to discover the potential for additive production in the food, dairy, and animal feed industries. In this study, after sampling the fermented products, the samples were identified using biochemical methods such as carbohydrate fermentation and ascospore production in newly optimized culture medium V8NLF containing vegetables. Proteolytic and lipolytic activities were performed to confirm the probiotic potential of selected samples, as well as their ability to grow at different pHs, different dilutions of bile salts and NaCl, sensitivity to common microbial antibiotics, and antimicrobial activity of yeast-produced metabolites against common pathogens. Finally, the optimal strains were molecularly identified. Three isolates with high probiotic potential were identified molecularly based on the results of biochemical and probiotic tests. The Y3 isolate was 100% identical to Saccharomyces cerevisiae, while strains Y23 and Y37 were 96.39% and 97.24% identical to Kluyveromyces marxianus, respectively. According to the findings of this study, Iranian fermented products have a high probiotic potential, and these bacteria can be used in the food and dairy industries, as well as to improve livestock and poultry feed.