青砖茶渥堆过程中理化特性及细菌多样性分析

目的 基于青砖茶渥堆过程中茶样理化特性及其中细菌种群的变化,揭示青砖茶品质形成与细菌菌群间的关联。方法 利用高通量测序技术对青砖茶从原料到陈化一个月过程中的9个时间节点的细菌多样性进行研究,同时检测其理化因子的动态变化,并进行冗余分析(redundancy analysis, RDA)。结果 通过细菌种群结构主成分分析可将整个青砖茶渥堆过程分为渥堆前期(W-0)、渥堆中期(W-1~W-7)、渥堆后期(陈化期)(C-1)。青砖茶渥堆过程中细菌多样性丰富,在门水平上,优势菌为proteobacteria,相对丰度为16.9%~91.0%,actinobacteria,其相对丰度为1.04%~49.5%,属水平上,klebsiella为渥堆起始点的优势菌,Burkholderia是渥堆过程的优势属,贯穿渥堆过程的始终,Weissella为W-3中出现特异性增加的细菌菌属,渥堆后期时出现优势菌属Pediococcus。RDA显示Saccharopolyspora与pH显著正相关,Chloroplast与水浸出物显著正相关,Microbacterium和色差指标、Bradyrhizobium与含水量、Streptomyces与可溶糖、Saccharopolyspora与黄酮、蛋白质、儿茶素、茶多酚等、Caballeronia与茶多糖和咖啡碱有正相关性。结论 细菌多样性与青砖茶渥堆过程理化特征指标及理化成分的变化表现出较强的相关性,细菌群落结构的变化是造成青砖茶渥堆过程中理化特性发生改变主要原因。

Analysis of physicochemical property and bacterial diversity during the pile-fermentation of Qingzhuan tea

Objective To reveal the correlation between the quality formation of Qingzhuan tea and the bacterial community based on the physical and chemical characteristics of tea samples and the changes of their bacterial community in the pile-fermentation process of Qingzhuan tea. Methods High throughput sequencing technology was used to study the bacterial diversity of Qingzhuan tea at 9 time points from raw material to one month of aging, and the dynamic changes of its physical and chemical factors were detected, and redundancy analysis (RDA) was conducted. Results The whole pile-fermentation process of Qingzhuan tea could be divided into early pile-fermentation (W-0), middle pile-fermentation (W-1-W-7) and late pile-fermentation (C-1) by principal component analysis of bacterial community structure. The bacterial diversity was rich in the pile-fermentation process of Qingzhuan tea. At the phylum level, the dominant bacteria were Proteobacteria, Firmicutes and Actinobacteria, with relative abundances of 16.87%?90.99%, 1.68%?58.69% and 1.04%?49.54%, respectively. At the genus level, Klebsiella was the dominant bacteria at the starting point of pile-fermentation, Burkholderia- Caballeronia-Paraburkholderia was the dominant genus during pile-fermentation proces, which ran through the whole pile-fermentation process, and was the dominant bacterium in the late pile-fermentation stage, Pediococcus was a bacterial genus with increased specificity in W-3. RDA showed Saccharopolyspora was significantly positively correlated with pH, Chloroplast was significantly positively correlated with water extract, Microbacterium and chromatic aberration indexes (b* and a*), Bradyrhizobium and water content, Streptomyces and soluble sugar, Saccharopolyspora and flavonoids, protein, catechin, tea polyphenols, Caballeronia and tea polysaccharide and caffeine had positive correlation. Conclusion There is a strong correlation between bacterial diversity and the changes of physical and chemical characteristics and components of Qingzhuan tea during pile-fermentation process, and the change of bacterial community structure is the main reason for the changes of physical and chemical characteristics of Qingzhuan tea during pile-fermentation process.