Journal of Tea Science Research, 2024, Vol.14, No.1, 44-51 http://hortherbpublisher.com/index.php/jtsr 46 complexity of interactions within microbial ecosystems, including species-species and species-environment interactions, as well as the feedbacks between ecological and evolutionary dynamics (eco-evo feedbacks) (Zerfaß et al., 2018). The goal is to create stable and efficient communities that can perform desired tasks more effectively than individual species or unengineered communities. 2.2 Overview of techniques used in microbial engineering 2.2.1 Genetic engineering of microbes Genetic engineering of microbes involves modifying the genetic material of microorganisms to alter their capabilities or behaviors. This can include adding, removing, or modifying specific genes to confer new metabolic pathways, resistance to toxins, or the ability to produce valuable compounds. Advances in molecular techniques, such as CRISPR-Cas systems, have greatly enhanced the precision and efficiency of genetic modifications in microbial engineering (Sheth et al., 2016). 2.2.2 Synthetic microbial communities (SynComs) Synthetic microbial communities, or SynComs, are designed by combining selected microorganisms to form a community with desired characteristics. This approach can involve the artificial selection of naturally occurring microbes, reduction from existing communities, or combinatorial evaluation of potential microbial combinations. Computational methods are increasingly used to optimize the design of SynComs for specific applications5. 2.2.3 Adaptive laboratory evolution Adaptive laboratory evolution (ALE) is a technique where microbial populations are exposed to controlled environmental conditions over extended periods, allowing for the natural selection of advantageous traits. This method can lead to the development of strains with improved performance characteristics, such as increased tolerance to stress or enhanced metabolic efficiency (Zerfaß et al., 2018). 2.2.4 Use of prebiotics and probiotics to modulate microbial communities The use of prebiotics and probiotics represents a strategy to modulate microbial communities by providing nutrients that selectively promote the growth of beneficial microbes (prebiotics) or by directly adding beneficial microorganisms to the community (probiotics). This approach can influence community-level properties and has applications in human health, agriculture, and biotechnology (Sheth et al., 2016). In summary, microbial community engineering is a multifaceted field that employs a variety of techniques to design and manipulate microbial ecosystems. These techniques range from genetic modifications of individual species to the construction of complex communities with specific functions. The ultimate aim is to harness the collective capabilities of microbes to address challenges in various domains, including environmental management, industrial bioprocessing, and health (Sheth et al., 2016; Zerfaß et al., 2018; Eng and Borenstein, 2019). 3 Recent Advances in Microbial Community Engineering for Tea Fermentation Recent advancements in microbial community engineering have significantly impacted the fermentation process of tea, leading to the development of novel fermented tea products with enhanced flavor, aroma, and health benefits. This section of the review paper will explore various case studies, genetic modifications, applications of synthetic communities (SynComs), and the overall impact of engineered microbial communities on the fermentation efficiency and product consistency of tea. 3.1 Case studies of engineered microbial communities in tea fermentation Several studies have demonstrated the role of microbial communities in the fermentation of traditional teas. For instance, the non-filamentous fungi growth-based fermentation process of Miang, a traditional fermented tea of North Thailand, showed that lactic acid bacteria (LAB), yeast, and Bacillus were the main microbial populations throughout the fermentation period (Unban et al., 2020). Similarly, the microbial community analysis of Sichuan South-road Dark Tea (SSDT) revealed that Aspergillus niger M10, isolated from SSDT, was excellent at enhancing organoleptic qualities such as soluble sugar, amino acids, and thearubigins contents (Zou et al., 2022).
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