【作者】 张京；

【导师】 许立达；

【作者基本信息】 北京化工大学 ， 化学工程与技术， 2021， 硕士

【摘要】 哺乳动物与肠道菌群及生态环境关系十分密切。各菌种与宿主通过密切合作来完成大量集体活动。但微生物群失衡可能导致多种疾病。研究表明在肠炎患者中肠道菌群微环境表现出明显失衡。服用抗生素是肠炎常见治疗手段之一,但抗生素的使用也面临着产生耐药菌以及抗性基因传播造成肠炎反复发作的风险。本文选用人类微生物组数据库中的炎症性肠病(Inflammatory Bowel Disease,IBD)患者宏基因组数据和代谢组学数据,利用聚类分析、NMDS分析以及差异分析等多种统计分析手段,根据metaphlan2的物种序列数据库和ResFinder水平转移抗性基因数据库,分析了抗生素服用前肠炎患者的肠道菌群失衡情况,抗生素使用过程中对物种多样性的影响以及抗性基因的传播情况,并通过OPLS-DA分析代谢组学,筛选差异代谢物并进行功能富集,解释了抗生素的使用对肠道菌群和宿主互作方面的干扰。在肠道菌群方面,抗生素使用前肠道微生物群失调,物种丰富度下降,抗生素使用期间呈现出部分物种相对丰度下降但多样性整体趋势有所上升,停用抗生素后物种比抗生素前多样性高但比使用期间低,对改善肠炎有益的菌种相对丰度升高,达到新的稳态和平衡。抗生素前后明显差异的物种有普拉梭菌和粪副拟杆菌等,这些菌都与短链脂肪酸的代谢有关,对肠炎的预后和治疗都具有重要作用。抗性基因方面,使用抗生素初期抗性基因不会立即大量产生,但随着抗生素使用时间的延长,抗性基因逐渐积累。以四环素类抗性基因的累积最为显著。通过对抗性基因的物种注释,拟杆菌属和副拟杆菌属菌易成为抗性基因的携带者。代谢组学方面,在抗生素使用的三个阶段代谢物组成具有明显过渡变化的趋势,其中具有显著性差异的代谢物有乙磺胺、糖精、胺类和肉碱等。对所有差异代谢物进行功能富集表明其中部分差异代谢物会参与到胆汁酸、脂肪酸等的代谢途径中,抗生素的使用会干预肠炎的预后。结合差异菌种、抗性基因及其物种来源以及差异代谢物,副拟杆菌属以及粪杆菌属在肠炎患者服用抗生素期间起到调节代谢物水平和转移抗性基因的重要角色,有望成为菌群耐药的干预手段。更多还原

【Abstract】 Mammals are closely related to intestinal microbes.Various strains and hosts cooperate closely to complete a large number of collective activities.However,the imbalance of the microbiota can lead to a variety of diseases.Studies have shown that the intestinal flora in patients with inflammatory bowel disease shows a significant imbalance.Taking antibiotics is one of the common treatments for enteritis,but the use of antibiotics also faces the risk of the production of drug-resistant bacteria and the transmission of resistance genes to cause repeated attacks of enteritis.This paper selects the metagenomic data and metabolomics data of patients with inflammatory bowel disease in the human microbiome database,using cluster analysis,NMDS analysis,PCA analysis and other statistical analysis methods,according to the species sequence database of metaphlan2 and ResFinder level transfer resistance gene database.We analyzed the imbalance of the intestinal flora of patients with antibiotics before enteritis,the impact of antibiotics on species diversity and the spread of resistance genes,and explains the effects of antibiotics on the intestinal tract through metabolomics—interference in the interaction between the flora and the host.In terms of intestinal flora,the intestinal microbiota was imbalanced before antibiotics were used,and species abundance declined.During antibiotic use,the relative abundance of some species declined,but the overall trend of diversity increased.After antibiotics were stopped,the species were more diverse than before antibiotics.The sex is high but lower than the period of use,and the relative abundance of bacteria beneficial to improving enteritis increases,reaching a new steady state and balance.Species with significant differences before and after antibiotics include Clostridium prasutii and Parabacteroides faecalis.These bacteria are all related to the metabolism of short-chain fatty acids and play an important role in the prognosis and treatment of enteritis.In terms of resistance genes,resistance genes will not be produced in large quantities at the initial stage of antibiotic use,but as antibiotics are used for a longer period of time,resistance genes gradually accumulate.The accumulation of tetracycline resistance genes is the most significant.Through the species annotation of resistance genes,Bacteroides and Parabacteroides easily become carriers of resistance genes.In terms of metabolomics,the composition of metabolites in the three stages of antibiotic use has a clear trend of transitional changes.Among them,metabolites with significant differences include ethanesulfonamide,saccharin,amines,and carnitine.Functional enrichment of all differential metabolites indicates that some of the differential metabolites will participate in the metabolic pathways of bile acids,fatty acids,etc.,and the use of antibiotics will interfere with the prognosis of enteritis.Combining different bacterial species,resistance genes and their species sources,and differential metabolites,Parabacter and Faebacterium play an important role in regulating metabolite levels and transferring resistance genes during enteritis patients taking antibiotics,and are expected to become flora Resistant interventions.更多还原