Characterization of SCOBY-fermented kombucha from different regions and its effect on improving blood glucose

Kombucha is a healthy fermented beverage made by fermenting sugar tea with a symbiotic culture of bacteria and yeast (SCOBY). The fermentation performance and antioxidant capacity of kombucha fermented by SCOBY from five different regions were compared in this study. Two kinds of high-quality SCOBY were selected, GKT and XKT. Next, the metabolite profiles of GKT and XKT were analyzed, and 18 and 36 different metabolites were screened from GKT and XKT, respectively. The correlation analysis of the differential metabolites with the antioxidant indexes identified three metabolites with potential hypoglycemic efficacy, 1-O-Sinapoyl-beta-Dglucose, Actinodaphnine, and Biochanin A. Moreover, the potential of GKT and XKT for anti-diabetes was verified by cell experiments. At the same time, the microbiome of GKT and XKT analysis found that Gluconobacter, , Komagataeibacter and Pseudomonas were the most common bacteria genera. Differently, the composition of fungal genera in GKT and XKT was differentiated, with the dominant genera being Filobasidium and Starmerella, , respectively. Finally, correlation analysis of microbial composition with volatile and functional metabolites showed that Gluconobacter and Komagataeibacter were closely related to flavor substances. In addition, the dominant strain of GKT, Filobasidium, , seems to contribute to its good sensory quality, and the dominant strain of XKT, Starmerella, , is positively associated with several metabolites with hypoglycemic effects, particularly Biochanin A and Rhoifolin. In this study, XKT was screened with good fermentation performance and strong antioxidant capacity, as well as had anti-diabetic potential. These results provide microbial resources and theoretical support for the development of kombucha starter culture.