Microbial Succession and the Dynamics of Chemical Compounds during the Solid-State Fermentation of Pu-erh Tea

Abstract

An in-depth knowledge of the microbiota and metabolites in the solid-state fermentation (SSF) of Post-fermented Pu-erh tea (Pu-erh Shucha, PFPT), a Chinese traditional tea with various health benefits, is essential to develop modern fermentation technology. In this work, the microbial diversity and succession in two laboratory-developed SSF protocols for PFPT were investigated using pyrosequencing analyses of the bacterial 16S rRNA and fungal 18S rRNA genes. The active bacteria in the initial stages of SSF (seven days) were from the raw materials and environment, with a dominance of Proteobacteria in both the raw materials and SSF after seven days. The environmental bacteria were inoculated into the tea mass throughout the fermentation process and multiplied, with a dominance of Firmicutes at day 14 and 21, and then Firmicutes and Actinobacteria at the last stages of fermentation (day 28 and 35). The dominant fungi came from the raw material and were identified at the genus level as Aspergillus throughout the SSF process. The contents of tea polyphenols, free amino acids, gallic acid, theaflavin, thearubigin, and catechins decreased significantly (p < 0.05), while the level of theabrownin increased significantly (p < 0.05). The caffeine content showed no significant change (p > 0.05). In total, 30 bacterial and three fungal genera showed significant correlations to 1-8 and 3-4 identified tea compounds, respectively (p < 0.05). The dynamics of the microbiota and chemical compounds, and correlations between their changes in the SSF of PFPT were revealed, and present a foundation for further studies on the microbial effects on chemical compounds.

Volatile flavour components, microbiota and their correlations in different sufu, a Chinese fermented soybean food

“…Aspergillus oryzae is one of the most important micro-organisms involved in the fermentation of soy sauce, and the autolysate may promote the flavour compounds such as alcohols, aldehydes, phenols and esters . Aspergillus was also predominant in vinegar Pei during acetic acid fermentation (Liu et al 2004; Wang et al 2016) and Pu-erh tea during postfermentation (Ma et al 2017b). This phenomenon was also consistent with previously published data in tofu substrate that Aspergillus, Pichia, Saccharomyces and Bacillus were dominant throughout the fermentation process, in which Aspergillus and Bacillus could produce potential proteolytic and amylolytic enzymes (Suntinanalert et al 2005).…”

“…) and Pu‐erh tea during postfermentation (Ma et al . ). This phenomenon was also consistent with previously published data in tofu substrate that Aspergillus , Pichia , Saccharomyces and Bacillus were dominant throughout the fermentation process, in which Aspergillus and Bacillus could produce potential proteolytic and amylolytic enzymes (Suntinanalert et al .…”

Bacterial diversity and community structure in Chongqing radish paocai brines revealed using PacBio single‐molecule real‐time sequencing technology

“…Nineteen species of Pseudomonas were identified from this genus in total (Table S2), with most identified as non‐infectious species, except for Pseudomonas oryzihabitans that was detected in sample W2, in a proportion of 0.03%. This genus has previously been shown to be dominant in Korean kimchi, ‘Jiaozi’, brined table olive, Pu‐erh tea, and ‘doubanjiang‐meju’, which is an anaerobic fermentation food derived from broad beans. Li et al .…”

Integrated Meta-omics Approaches To Understand the Microbiome of Spontaneous Fermentation of Traditional Chinese Pu-erh Tea

“…As a well-known traditional Chinese fermented food with multiple health benefits, such as hypolipidemic, antimutagenic, antioxidative, antitumor, antiobesity, and toxicity-suppressing activities (16), it is popular in Southeast Asia and is becoming increasingly popular in the Western world. Microbial communities in the fermentation of pu-erh tea have previously been studied using culture methods and culture-independent approaches, including denaturing gradient gel electrophoresis, 16S rRNA gene clonal library, and next-generation sequencing (17). Recently, a study by Li et al (18) using shotgun metagenomic and metabolomic analyses showed that significant variations in the composition of microbiota, collective functional genes, and flavor compounds occurred during the fermentation process.…”