普洱茶固态发酵过程中微生物群落结构及变化

Microbial Community Structure and Change during Solid Fermentation of Pu-erh Tea

以少量茶叶发酵制备普洱茶过程中的茶叶样品为研究对象,采用聚合酶链式反应-变性梯度凝胶电泳(PCRDGGE)技术分别对茶叶中细菌16S rRNA和真菌18S rRNA的PCR产物进行分离,根据基因指纹图谱分析群落结构及其动态变化过程,并对细菌和真菌的主要优势条带进行克隆、测序、构建系统发育树。结果表明:茶叶堆表和堆芯的微生物群落结构差异小;在发酵过程中,细菌和真菌的种类均在二翻时迅速增加,群落结构产生显著变化;而后不同种类的数量随着发酵时间的推进有规律地增加或减少,最后趋于稳定。黑曲霉是发酵前期的优势菌种,芽孢杆菌属和Arxula adeninivorans是普洱茶发酵后期的主要优势菌群。

Polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） was used to separate the bacterial 16S rRNA and fungal 18S rRNA PCR products, and DGGE profiles were applied to analyze the bacterial and fungal community structures and their changes during the fermentation of Pu-erh tea. Dominant DNA bands on the DGGE gels were recovered and cloned into E. coli, and the targeted clones were sequenced. Based on the blasted nucleotide sequences, bacterial 16S rRNA and fungal 18S rRNA Neighbor-Joining phylogenetic trees were constructed. The results suggested the difference in microbial community structure between tea pile surface and inner was not obvious. Bacterial and fungal populations revealed a rapid increase after the second fermentation stage, and the structures of bacterial and fungal communities exhibited a significant change as fermentation time was prolonged. At the last stage of the fermentation process, the microbial communities were steady; and Aspergillus niger was the dominant species at the early stage and Bacillus and Arxula adeninivorans were the dominant ones at the late stage.