Journal of Tea Science Research, 2024, Vol.14, No.2, 92-101 http://hortherbpublisher.com/index.php/jtsr 94 3.3 Comparative analysis of microbial diversity in other tea types Other types of fermented teas, such as Pu-erh and Fuzhuan brick tea, exhibit unique microbial profiles. In Pu-erh tea, the dominant bacteria are Proteobacteria, while Aspergillus is the predominant fungus (Zhao et al., 2015). The microbial community in Fuzhuan brick tea is characterized by a higher abundance and diversity of bacterial communities (Figure 1), with Lactococcus and Bacillus being the main bacteria, and Eurotiumas the predominant fungus (Xia et al., 2012). The microbial composition in these teas is crucial for the development of their unique flavors and bioactive compounds. For instance, in Sichuan South-road Dark Tea, Aspergillus niger plays a significant role in enhancing the tea's organoleptic qualities by producing enzymes such as β-glucosidase and pectinase, which contribute to the tea's sweet and mellow taste (Zou et al., 2022). Figure 1 Relative abundance of the bacterial community at the phylum (A), family (B), genus (C), and species (D) levels throughout the fermentation period (Adopted from Unban et al., 2020) Unban et al. (2020) demonstrated the relative abundance changes of bacterial communities at the four levels of phylum, family, genus, and species during the fermentation process. From the graph, it can be seen that during fermentation, Proteobacteria and Firmicutes are the main bacterial phyla, with relatively stable abundance. The diversity changes from family to species level indicate that certain genera and species in families such as Lactobacillaceae and Streptococcaceae become more prominent during the fermentation process. These changes may be related to environmental factors, selectivity of fermentation substrates, and interactions between microorganisms, reflecting the dynamic balance of microbial community structure and its adaptability to the fermentation environment. 4 Case Studies in Tea Fermentation 4.1 Case study: metagenomic insights from Pu'er tea fermentation Pu'er tea fermentation is a complex process involving a diverse microbial community that significantly influences the tea's quality and flavor (Figure 2). Shotgun metagenomic and metabolomic analyses have revealed substantial variations in the composition of microbiota, functional genes, and flavor compounds during the solid-state fermentation (SSF) process. Key microorganisms such as Aspergillus, Bacillus, Rasamsonia, Lichtheimia, and Debaryomyces play crucial roles at different stages of fermentation, contributing to the production of dominant flavors like theabrownin and methoxy-phenolic compounds (Kong et al., 2022). Additionally, integrated metagenomics and metaproteomics approaches have identified Proteobacteria and Aspergillus as dominant taxa,
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