Isolation of Kombucha Microorganisms for Application in Perilla Beverage Fermentation.

The increasing consumer demand for kombucha in Vietnam necessitates the development of standardized microbial starter cultures for functional beverage production. This study isolated and evaluated microbial consortia from five commercial kombucha samples using selective media: Yeast extract Peptone Glycerol Dextrose (YPGD) for acetic acid bacteria (AAB), MRS for lactic acid bacteria (LAB), and Yeast extract Peptone Dextrose Agar (YPDA) for yeasts. Based on morphological and biochemical characteristics, a total of 22 AAB strains, 6 LAB strains, and 9 yeast isolates were recovered. Sequence analysis revealed that selected strains shared high similarity with key species: Komagataeibacter saccharivorans, Levilactobacillus brevis, and Wickerhamomyces anomalus. Experimental evaluation with perilla extract revealed that a 15% sugar concentration combined with a yeast: AAB: LAB inoculation ratio of 2:2:1 performed favorably fermentation kinetics, with total flavonoid content (TFC) retention increased by 5%-10%, total anthocyanin content (TAC) elevated 300%-400% at day 3, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant capacity maintained at 2.49 mg AAE/mL at Day 6 compared to other ratios. These results substantiate the potential of the isolated microbial strains as effective starter cultures for herbal beverage fermentation. Further studies on metabolic characteristics, sensory properties, and scale-up are recommended to support industrial application.