Metagenomic analysis of flavonoid-metabolizing microorganisms in temperature-controlled fermentation of Liupao tea

Liupao tea is known for its lipid-lowering properties; the key to its quality lies in its microorganism-driven secondary fermentation. However, systematic research on the microbial regulation of flavonoid metabolism in Liupao tea remains scarce. We compared the effects of different fermentation temperatures on Liupao tea quality. The sensory quality and biochemical characteristics of the 45 °C constant-temperature fermentation group (HW) and variable-temperature fermentation group (BW) were significantly superior to those of other groups. Compared to the natural fermentation (CK) group, the temperature-controlled fermentation groups showed an average fourfold increase in flavonoid content, with 25/41 flavonoid compounds exhibiting significant changes. The phyla Ascomycota and Mucoromycota, and the genera Aspergillus, Lichtheimia, Fennellomyces, Syncephalastrum, Rhizopus, and Circinella showed high abundance; 12 functional microbial taxa were significantly correlated with flavonoid accumulation in Liupao tea. Overall, these findings provide a theoretical foundation for optimizing Liupao tea fermentation and enhancing flavonoid biosynthesis through microbial regulation.