Comparative Metagenomics Reveals Microbial Communities and Their Associated Functions in Two Types of Fuzhuan Brick Tea.

Tianli Yue,Chunfeng Guo,Gengan Du,Yahong Yuan,Hong Chen,Xin Wang,Xuejun Zeng,Bin Liu,Qinglin Sheng

doi:10.3389/fmicb.2021.705681

Abstract

Fuzhuan brick tea (FBT) is a unique post-fermented tea product, naturally co-fermented by microorganisms, and has gained global popularity due to its potential health benefits for humans. Considerable efforts have been made toward elucidating the microbial diversity within FBT, but an understanding of the underlying FBT community interactions and functions remains poorly studied. Consequently, the microbial communities of two types of FBT, originating from Hunan and Shaanxi provinces, were investigated using comparative shotgun metagenomic sequencing and functional annotations. Metagenomic analysis indicated that two communities shared similar taxonomic and functional attributes. Two samples shared 486 genera, in which Pseudomonas contributed most to the abundant functions within the two samples. The carbohydrate active enzyme functions of the communities primarily comprised GH (32.92%), GT (26.8%), CEs (20.43%), and AAs (18.04%). Furthermore, the overall metabolic pathways encoded by the metagenomes were largely associated with carbohydrate and amino acid metabolism, with nine metabolic pathways that were differential between two groups including penicillin and cephalosporin biosynthesis. Significantly, a total of 35 potential probiotics were inferred, with Pseudomonas putida being the most abundant inferred probiotic (80%) within the FBT communities. This study provides new insights into FBT microbial communities on their potential functions and roles in FBT characteristics.

Highlights

Fuzhuan brick tea (FBT) is a fermented tea product that has been consumed in China over 3,000 years and has since become popular in many countries (Li et al, 2018)
The two FBT communities were dominated by the genus Pseudomonas (73.97%, 78.74%), followed by Enterobacteriaceae (4.83%, 7.13%), and Citrobacter (4.59%, 7.10%); Comamonas (4.35%, 0.26%), Stenotrophomonas (2.05%, 0.19%), Leclercia (1.08%, 0), and Rhizobiaceae (0.87%, 0) were more abundant in FBT_H than FBT_S (Figure 1A), suggesting that the difference might be due to the unique processing of FBT of the two brands not due to different regions
The specific contributions of Citrobacter and unclassified Enterobacteriaceae were associated with the M00122 (Figure 4B), consistent with the module function analysis above

Summary

Introduction

Fuzhuan brick tea (FBT) is a fermented tea product that has been consumed in China over 3,000 years and has since become popular in many countries (Li et al, 2018). Increasing numbers of studies have confirmed the health benefits of FBT including antihyperlipidemia (Wang and Ho, 2009), anti-dysentery (Zhang et al, 2013), anti-obesity (Li et al, 2013), anti-hyperglycemia (Yamashita et al, 2012), and anti-oxidation (Cheng et al, 2015) effects. These health effects are closely related to the bacterial and fungal communities present within FBT that have been recently studied with culture-based or cultivation-independent methods (Tamang et al, 2016). The effects of microbial community changes on the functional diversity in FBT remain poorly understood

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Conclusion