In vitro Functional Characterization of Potential Probiotic Yeasts from Ethnic Fermented Cow Milk Products of Sikkim, India
Sonam Lama, Jyoti Prakash Tamang, Vijay Shankar SinghIntroduction:
Although numerous bacterial probiotics are employed in the probiotic industry, only a few yeast probiotics have been utilized for this purpose. Dahi and chhurpi are traditionally fermented milk products of Sikkim, India, and they are also consumed in other parts of the country due to their health-enhancing properties.
Methods:
In the present study, identified yeast isolates from fermented cow milk products were evaluated for growth at different temperatures, different salt concentrations, and tolerance to in vitro digestive conditions. Isolates were also evaluated for safety and characterized for health-enhancing functional attributes.
Results:
Most of the isolates were found to be safe based on the safety evaluation tests, except Meyerozyma guilliermondii CMN-3 and Yarrowia lipolytica CBG-9. Among 20 yeast isolates, Saccharomyces cerevisiae DRC-41 showed the highest cholesterol-lowering activity (54.48 ± 0.7%), Kluyveromyces marxianus DPA-41 exhibited the strongest antioxidant activity (82.22 ± 0.3%), Kl. marxianus DPA-41 showed the highest anti-inflammatory activity (59.74 ± 0.33%), and Kl. marxianus DPA-41 stood out as the most effective isolate for anti-diabetic activity (12.1 ± 0.86%). Similarly, yeasts were also screened for exopolysaccharide production, phytate hydrolyzing activity, beta- D-glucosidase activity, beta-galactosidase activity, and antifungal activity. A PCA biplot was designed and based on the score value obtained by the isolates on the variance-covariance matrix at 10k bootstrap value, Kl. marxianus DPA-41 from cow dahi and S. cerevisiae CRC-35 from cow chhurpi were selected as functional isolates with the highest potential.
Discussion:
The present study evaluated potential probiotic yeast isolates from traditional fermented cow milk products of Sikkim, India, for their tolerance to simulated in vitro digestive conditions, safety, and functional attributes. Several isolates exhibited tolerance to physiological temperatures, salt stress, and simulated digestive conditions. Additionally, genetic screening supported acid and bile tolerance in selected strains. Safety evaluation confirmed the absence of virulence-associated traits in most of the isolates. Functional evaluation revealed cholesterol-lowering, antioxidant, antiinflammatory, anti-diabetic, and other health-enhancing properties in most of the isolates. Based on statistical analysis, Kl. marxianus DPA-41 from cow dahi and S. cerevisiae CRC-35 from cow chhurpi were selected as promising candidates with no safety issues. These findings highlight the potential of indigenous yeasts as functional probiotic cultures for food applications.
Conclusion:
Based on the statistical analysis, potential probiotic yeast isolates with healthenhancing functional properties were reported. Further genome and metabolomic studies on these isolates will enable their effective application in the food industry.