水平基因转移（Horizontal gene transfer，HGT）被认为是原核生物进化的重要动力所在，使基因能够在不同个体之间横向传播流动，对提升物种的适应能力有着重要意义。而肠道作为水平基因转移发生的熔炉，其中的水平基因转移事件既影响着肠道微生物在肠道环境中的生存能力，也是促进抗生素耐药性基因（antibiotic resistance genes，ARG）传播的重要途径。脆弱拟杆菌（Bacteroides fragilis，B.fragilis）是人体肠道中极为重要的一种肠道共生菌，作为一种条件致病菌，脆弱拟杆菌与人体健康和肠道疾病息息相关。本研究针对脆弱拟杆菌的水平基因转移进行相关研究，借助现有的数据库获取脆弱拟杆菌的基因组信息，通过与同属内物种基因组信息比较，初步筛选出可能的水平基因转移相关基因，并利用BLAST（Basic Local Alignment Search Tool）搜索相似基因序列，通过进化树分析法与碱基含量分析法进行比较确认。寻找到水平基因转移的相关基因后，则借助BlastKOALA工具了解基因功能。最终，研究得到了3个水平转移进入脆弱拟杆菌中的基因。其中一个基因的蛋白质产物4-oxalocrotonate tautomerase拥有降解芳香族化合物的功能，帮助脆弱拟杆菌在可以利用二甲苯等芳香族化合物作为碳源的同时拥有降解有毒芳香族化合物的解毒能力，对提升脆弱拟杆菌的生存能力有着重要意义。

Horizontal gene transfer (HGT) is considered a significant driving force in the evolution of prokaryotes, enabling genes to horizontally propagate and flow between different individuals, which is crucial for enhancing species' adaptability. The gut serves as a crucible for HGT events, where HGT not only impacts the survival capacity of gut microbiota in the intestinal environment but also acts as an important pathway for the dissemination of antibiotic resistance genes (ARGs). Bacteroides fragilis (B. fragilis) is a highly significant intestinal symbiotic bacterium in the human gut. As an opportunistic pathogen, B. fragilis is closely related to human health and intestinal diseases. This study focuses on the HGT events in B. fragilis. Utilizing existing databases, we obtained the genomic information of B. fragilis and initially screened potential HGT-related genes by comparing them with the genomic information of species within the same genus. BLAST (Basic Local Alignment Search Tool) was employed to search for similar gene sequences, and comparative confirmation was conducted through phylogenetic tree analysis and base content analysis. After identifying the relevant genes involved in HGT, we utilized the BlastKOALA tool to understand their functions. Ultimately, the study identified three genes horizontally transferred into B. fragilis. One of these genes encodes the protein 4-oxalocrotonate tautomerase, which possesses the function of degrading aromatic compounds. This enzyme not only allows B. fragilis to utilize aromatic compounds such as xylene as a carbon source but also enables it to detoxify toxic aromatic compounds, significantly enhancing its survival capability.