Evaluation of probiotic and antifungal properties of the selected yeast isolated from fermented black rice

Probiotic and antifungal properties of the yeasts isolated from fermented pseudo cereals have been rarely studied, yet. In the present study, after isolation of predominant yeasts isolated from fermented black rice, the yeast with the highest survival in simulated gastrointestinal conditions was selected for further studies. Then, the selected isolate was identified by PCR, and subsequently, its probiotic properties including antibacterial effects, antibiotic and antimycotic susceptibilities, aggregation, hydrophobicity and hemolytic potentials were also studied. Antifungal activity of the selected yeast was investigated against some of the foodborne fungi. Sequencing of the PCR products led to the identification of Rhodotorula mucilaginosa as the selected yeast isolate. The isolate maintained 84.39% of its survival in continues acid and bile treatment. Also, the inhibitory effect of the yeast isolate on Salmonella enterica was significantly (p<0.05) higher than the other foodborne bacteria. Yeast isolate had proper aggregation and hydrophobicity capabilities, and it was resistant to the antibiotics tested. Furthermore, the most inhibition of the yeast growth was observed in the presence of ketoconazole, while the selected yeast was resistant to propionate, sorbate, itroconazole and fluconazole. The studied yeast isolate had no hemolytic activity. The antifungal effect of the yeast isolate against Aspergillus flavus was also verified. In accordance with these results, the selected yeast isolate has a proper potential to use as a probiotic or protective culture in production of fermented foods.