源于甘草内生菌的甘草酸合成相关 功能基因的宏基因组挖掘

Objective: Licorice is widely used as a traditional Chinese medicine. Glycyrrhizin is the main active ingredient in licorice, a pentacyclic trterpenoid compound, has many pharmaceutical functions, such as anti-inflammatory, antiviral, and liver protection, and has been used in the clinical treatment of COVID-19. With the development of metabolic engineering and synthetic biology, the microbial synthesis of glycyrrhizin and its precursors has been gradually realized. However, the yield is low due to the incompatibility between plant genes and microbial chassis. In last decades, endophytes have been reported to harbor a wealth of functional traits, and could be directly or indirectly used for the production of plant-derived active compounds, indicating that investigation on endophytes has great academic potentials and application values in the field of metabolic engineering. Therefore, this study intends to conduct an in-depth study on the endophyte community of licorice and dig out the microbial-source functional genes that can be used for glycyrrhizin synthesis. Methods: In this study, three year old main root samples of Glycyrrhiza uralensis were collected from Emin County, Tacheng City, Xinjiang Uygur Autonomous Reyion. Metagenomic sequencing of endophytic communities was carried out, and the community structure and functional gene diversity of endophytic communities were analyzed. Through functional gene annotation and phylogenetic analysis, functional genes that may be involved in glycyrrhizin synthesis were excavated. Results: By analyzing the abundance of the community structure, it was found that the dominant endophytes in the licorice root were Steroidobacter denitrificans, Phenylobacterium zucineum, unclassified Phenylobacterium, and Phenylobacterium sp. . The metagenomic data were functionally annotated by COG database, KEGG database, and CAZy database, and the endophytic genes encoding enzymes involved in glycyrrhizin synthetic pathway, such as cytochrome P450 and UDP-glycosyltransferase, were found to be abundant in the endophytes of licorice. Conclusion; This study was the first to use metagenomic sequencing and analysis methods to understand the community structure and functional gene composition of endophytes from G. uralensis. It was proved that the endophytic community contained abundant cytochrome P450 and UGT coding genes, which laid a theoretical foundation for further comprehensive and in-depth study of the biological functions of endophytes from G. uralensis and how they transform into glycyrrhizin biosynthesis resources.