An acid-tolerant ammonia-oxidizing γ-proteobacterium from soil
An acid-tolerant ammonia-oxidizing γ-proteobacterium from soil
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DOI：
10.1038/ismej.2016.191
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发表时间：
2017-05-01
期刊：
影响因子：
11
通讯作者：
Takami, Hideto
中科院分区：
文献类型：
--
作者：
Hayatsu, Masahito;Tago, Kanako;Takami, Hideto
硝化作用，即微生物通过亚硝酸盐将氨氧化为硝酸盐，发生在广泛的酸性土壤中。然而，迄今为止从土壤中分离到的氨氧化细菌（AOB）对酸敏感。在这里，我们报道了从酸性农业土壤中分离和鉴定一种适应酸的AOB。根据系统发育特征，分离的AOB菌株TAO100被归类为γ变形菌门。在pH值为5-7.5的环境中，TAO100可以生长，在pH值为2的高酸性条件下，通过形成细胞聚集体存活。虽然所有已知的从海洋和咸水环境中分离出来的γ变形菌AOB （γ -AOB）物种都是嗜盐菌，但TAO100在表型上不是嗜盐菌。因此，陶100代表了第一个土壤源的非嗜盐性γ - aob。与其他γ - aob相比，TAO100的基因组要小得多，并且缺少几个与耐盐性相关的基因，这些基因对土壤中的生存是不必要的。在强酸性土壤中，陶100的氨单加氧酶亚基A基因及其转录本的丰度高于氨氧化古菌和β变形菌AOB。这些结果表明，陶100在酸性土壤的硝化作用中起着重要作用。基于这些结果，我们认为TAO100是一个新属Candidatus Nitrosoglobus terrae的新种。
Nitrification, the microbial oxidation of ammonia to nitrate via nitrite, occurs in a wide range of acidic soils. However, the ammonia-oxidizing bacteria (AOB) that have been isolated from soil to date are acid-sensitive. Here we report the isolation and characterization of an acid-adapted AOB from an acidic agricultural soil. The isolated AOB, strain TAO100, is classified within the Gammaproteobacteria based on phylogenetic characteristics. TAO100 can grow in the pH range of 5-7.5 and survive in highly acidic conditions until pH 2 by forming cell aggregates. Whereas all known gammaproteobacterial AOB (gamma-AOB) species, which have been isolated from marine and saline aquatic environments, are halophiles, TAO100 is not phenotypically halophilic. Thus, TAO100 represents the first soil-originated and non-halophilic gamma-AOB. The TAO100 genome is considerably smaller than those of other gamma-AOB and lacks several genes associated with salt tolerance which are unnecessary for survival in soil. The ammonia monooxygenase subunit A gene of TAO100 and its transcript are higher in abundance than those of ammonia-oxidizing archaea and betaproteobacterial AOB in the strongly acidic soil. These results indicate that TAO100 plays an important role in the nitrification of acidic soils. Based on these results, we propose TAO100 as a novel species of a new genus, Candidatus Nitrosoglobus terrae.