Effects of Enhanced Bacillus circulans Fermented Tibetan Tea on Intestinal Microbiota and Hepatic Antioxidant Capacity of Mice

Abstract Tibetan tea is a typical dark tea, whose processing is highly dependent on pile-fermentation. During microbial fermentation, microorganisms, including Bacillus circulans, and their metabolites induce several biochemical reactions, each with unique roles in the resulting tea quality and flavor. The primary aim of the current study was to investigate the chemical composition and beneficial health effects of enhanced Tibetan tea, generated via B. circulans fermentation, in a murine model. To this end, changes in the chemical composition of Tibetan tea extracts were analyzed before and after fermentation via ultra-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry. The effects of fortified fermented Tibetan tea on the intestinal microbiota and hepatic antioxidant capacity of mice were then evaluated. The contents of catechins derivatives, flavonoids, phenolic acids, and terpenoids were increased in Tibetan tea following fermentation (the proportion of each chemical component increased by 0.3, 2.38, 2.65, and 3.36%, respectively, relative to its unfermented level). Moreover, 16S ribosomal RNA sequence analyses revealed that fermented Tibetan tea regulates the intestinal microbiota of mice. The relative abundance of Lactobacillus spp. was increased following fermented tea consumption. Based on the histological and quantitative PCR analyses, fermented Tibetan tea can also improve intestinal development and intestinal barrier functions, while increasing the hepatic antioxidant capacity of mice. Hence, enhanced fermented Tibetan tea improves the beneficial effects mediated by murine intestinal microbiota. These findings provide a theoretical basis for further evaluation of the effects of microorganisms on Tibetan tea, as well as its potential application as a functional food.