Nitrogen fixation in the human gut by sulphate-reducing bacteria

我最近的研究结果令人兴奋地发现了一种硫酸盐还原细菌（SRB），来自人类肠道的重氮营养型Desulfovibrio diazotrophicus，它可以在体外固定氮。虽然在一些动物的肠道微生物群中发现了固氮细菌，如白蚁和反刍动物，但对人类的固氮过程知之甚少。证明固氮发生在人体肠道微生物群中将是一项重大的科学发现，并扩大我们对人体内氮循环和微生物相互作用的理解。因此，这项研究对人类健康和营养以及微生物组的作用具有重要意义。肠道内细菌群的组成和活性受到宿主饮食的影响，特别是营养物质的可用性。研究细菌种群对饮食中不同氮水平和可用性的反应，为探索固氮是否受到我们食物摄入量的影响提供了机会。本研究旨在确定当食用低蛋白饮食时，重氮营养（固氮）细菌是否在人体肠道中具有竞争优势。我的宏基因组学分析发现，虽然SRB经常存在于人类肠道微生物群中，但并非所有物种都有固定氮的潜力。部分SRB种对蛋白质缺乏饲粮的生物可利用氮有贡献；然而，SRB的大量繁殖与结肠疾病、肠道炎症和溃疡性结肠炎有关。SRB呼吸的副产物H2S在高浓度时是有毒的，但也可以抗炎。因此，该项目将更好地了解SRB在肠道中的生态和代谢，这对于了解它们是否对健康有益或潜在有害至关重要。我的目的是研究固氮对重氮营养菌生存和代谢的影响，固氮对微生物群和宿主的影响，以及饮食如何影响这些相互作用。假设硫酸盐还原菌可以在胃肠道条件下固定氮，这一过程受膳食蛋白质的数量和来源的影响，从而影响H2S的产生。此外，假设固定氮与其他微生物群共享或被宿主利用。具体目标是：研究重氮营养菌在肠道环境中的固氮速率，如果这些氮是共享的；确定纯素饮食对重氮营养菌固氮的影响，并确定复杂微生物内部的关键相互作用评估重氮营养菌对宿主氮库和肠道通透性的影响我在人类肠道中发现固氮SRB的发现有可能彻底改变我们对人类营养、营养和营养之间复杂相互作用的理解。微生物群和健康。缺乏蛋白质的饮食会导致营养不良，对老年人和孕妇等弱势群体可能造成严重影响。研究结果将为新的营养策略提供信息，以解决纯素饮食、老年人和营养不良人群中的蛋白质缺乏问题。

My recent research has resulted in the exciting discovery of a sulphate-reducing bacterium (SRB) from the human gut, Desulfovibrio diazotrophicus, which fixes nitrogen in vitro. While nitrogen-fixing bacteria have been found in the gut microbiomes of some animals, such as termites and ruminants, little is known about the process of nitrogen fixation in humans. Demonstrating that nitrogen fixation occurs in the human gut microbiome would represent a significant scientific finding and expand our understanding of the nitrogen cycle and microbial interactions within the human body. This research, therefore, has implications for human health and nutrition as well as the role of the microbiome.The composition and activity of bacterial populations in the gut are influenced by the host's diet, particularly the availability of nutrients. Investigating bacterial populations in response to different nitrogen levels and availability in the diet provides an opportunity to explore whether nitrogen fixation is influenced by our food intake. This research aims to determine whether diazotrophic (N-fixing) bacteria have a competitive advantage in the human gut when low-protein diets are consumed.My metagenomics analyses found that while SRB are frequently present in human gut microbiomes, not all species have the potential to fix nitrogen. Some SRB species could contribute to the bioavailable nitrogen in protein-deficient diets; however, blooms of SRB have been linked with colonic diseases, gut inflammation, and ulcerative colitis. The by-product of SRB respiration, H2S, is toxic in high concentrations but can also be anti-inflammatory. Therefore, this project will provide a better understanding of SRB ecology and metabolism in the gut, which is crucial to understanding whether they are beneficial or potentially harmful to health.I aim to investigate the impact of nitrogen fixation on D. diazotrophicus survival and metabolism, the effects nitrogen fixation has on the microbiota and the host, and how diet influences these interactions. The hypotheses are that sulphate-reducing bacteria can fix nitrogen under gastrointestinal conditions, and this process is influenced by the quantity and source of dietary protein, subsequently affecting H2S production. Additionally, it is hypothesized that fixed nitrogen is shared with the rest of the microbiota or utilized by the host. The specific objectives are:Investigate the rate of nitrogen fixation by D. diazotrophicus in the gut environment, if this nitrogen is shared, and assess the extent to which this process is influenced by dietary protein contentDetermine the influence of vegan diets on nitrogen fixation by D. diazotrophicus and identify key interactions within a complex microbiotaEvaluate the impact of D. diazotrophicus on the host's nitrogen pool and gut permeabilityImplicationsMy discovery of nitrogen-fixing SRB in the human gut has the potential to revolutionize our understanding of the complex interactions between human nutrition, the microbiome and health. Protein-deficient diets cause malnutrition and can be severe for vulnerable populations, as the elderly and pregnant women. The outcomes will inform new nutritional strategies that could address protein deficiency in vegan diets, the elderly and the malnourished.