Nitrogen fixation and nifH diversity in human gut microbiota.
Nitrogen fixation and nifH diversity in human gut microbiota.
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DOI：
10.1038/srep31942
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发表时间：
2016-08-24
影响因子：
4.6
通讯作者：
Umezaki M
中科院分区：
文献类型：
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作者：
Igai K;Itakura M;Nishijima S;Tsurumaru H;Suda W;Tsutaya T;Tomitsuka E;Tadokoro K;Baba J;Odani S;Natsuhara K;Morita A;Yoneda M;Greenhill AR;Horwood PF;Inoue J;Ohkuma M;Hongoh Y;Yamamoto T;Siba PM;Hattori M;Minamisawa K;Umezaki M
据推测，固氮作用发生在人类肠道中。然而，肠道微生物群是否真的具有这种潜力仍不清楚。我们研究了人类粪便微生物群中固氮酶还原酶（NifH）基因的固氮活性和多样性，重点关注习惯性氮摄入量从低到高的巴布亚新几内亚和日本个体。 15N2 掺入测定显示，无论宿主氮摄入量如何，所有粪便样本中 15N 均显着富集，乙炔还原测定也支持这一点。固定氮相当于人类标准氮需求的 0.01%，尽管我们的数据表明体内肠道的贡献可能高于这个值。在克隆和宏基因组分析中回收的 nifH 基因被分为两类：一类包含与克雷伯氏菌序列几乎相同的序列，另一类包含与梭菌目成员的序列相关的序列。这些结果与对其他人群粪便宏基因组数据库的分析一致。总的来说，人类肠道微生物群具有固氮潜力，这可能归因于克雷伯菌属和梭状芽胞杆菌菌株，尽管没有证据表明固氮活性对宿主氮平衡有实质性贡献。
It has been hypothesized that nitrogen fixation occurs in the human gut. However, whether the gut microbiota truly has this potential remains unclear. We investigated the nitrogen-fixing activity and diversity of the nitrogenase reductase (NifH) genes in the faecal microbiota of humans, focusing on Papua New Guinean and Japanese individuals with low to high habitual nitrogen intake. A 15N2 incorporation assay showed significant enrichment of 15N in all faecal samples, irrespective of the host nitrogen intake, which was also supported by an acetylene reduction assay. The fixed nitrogen corresponded to 0.01% of the standard nitrogen requirement for humans, although our data implied that the contribution in the gut in vivo might be higher than this value. The nifH genes recovered in cloning and metagenomic analyses were classified in two clusters: one comprising sequences almost identical to Klebsiella sequences and the other related to sequences of Clostridiales members. These results are consistent with an analysis of databases of faecal metagenomes from other human populations. Collectively, the human gut microbiota has a potential for nitrogen fixation, which may be attributable to Klebsiella and Clostridiales strains, although no evidence was found that the nitrogen-fixing activity substantially contributes to the host nitrogen balance.