Gut Health and Microbes, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK.
State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi, China.
Environ Microbiol. 2021 Jun;23(6):3164-3181. doi: 10.1111/1462-2920.15538. Epub 2021 May 14.
Sulfate-reducing bacteria (SRB) are widespread in human guts, yet their expansion has been linked to colonic diseases. We report the isolation, sequencing and physiological characterization of strain QI0027 , a novel SRB species belonging to the class Desulfovibrionia. Metagenomic sequencing of stool samples from 45 Chinese individuals, and comparison with 1690 Desulfovibrionaceae metagenome-assembled genomes recovered from humans of diverse geographic locations, revealed the presence of QI0027 in 22 further individuals. QI0027 encoded nitrogen fixation genes and based on the acetylene reduction assay, actively fixed nitrogen. Transcriptomics revealed that QI0027 overexpressed 42 genes in nitrogen-limiting conditions compared to cultures supplemented with ammonia, including genes encoding nitrogenases, a urea uptake system and the urease complex. Reanalyses of 835 public stool metatranscriptomes showed that nitrogenase genes from Desulfovibrio bacteria were expressed in six samples suggesting that nitrogen fixation might be active in the gut environment. Although frequently thought of as a nutrient-rich environment, nitrogen fixation can occur in the human gut. Animals are often nitrogen limited and have evolved diverse strategies to capture biologically active nitrogen, ranging from amino acid transporters to stable associations with beneficial microbes that provide fixed nitrogen. QI0027 is the first Desulfovibrio human isolate for which nitrogen fixation has been demonstrated, suggesting that some sulfate-reducing bacteria could also play a role in the availability of nitrogen in the gut.
硫酸盐还原菌（SRB）广泛存在于人类肠道中，但它们的扩张与结肠疾病有关。我们报告了一种新型的硫酸盐还原菌属 Desulfovibrionia 种的分离、测序和生理特性，即菌株 QI0027。对来自 45 位中国个体的粪便样本进行宏基因组测序，并与来自不同地理位置的人类的 1690 个脱硫弧菌科宏基因组组装基因组进行比较，结果表明在另外 22 位个体中存在 QI0027。QI0027 编码固氮基因，并且基于乙炔还原测定法，积极地固定氮。转录组学研究表明，与添加氨的培养物相比，QI0027 在氮限制条件下过度表达了 42 个基因，包括固氮酶、尿素摄取系统和脲酶复合物的基因。对 835 个公共粪便宏转录组的重新分析表明，来自脱硫弧菌的固氮酶基因在 6 个样本中表达，这表明氮固定可能在肠道环境中活跃。尽管人们通常认为肠道环境富含营养物质，但氮固定也可以在肠道中发生。动物通常受到氮的限制，并进化出多种策略来捕获生物活性氮，从氨基酸转运体到与提供固定氮的有益微生物的稳定关联。QI0027 是第一个被证明具有固氮能力的脱硫弧菌人类分离株，这表明一些硫酸盐还原菌也可能在肠道中氮的可用性方面发挥作用。
