Ecophysiology of an Ammonia-Oxidizing Archaeon Adapted to Low-Salinity Habitats
Ecophysiology of an Ammonia-Oxidizing Archaeon Adapted to Low-Salinity Habitats
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DOI：
10.1007/s00248-012-0075-1
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发表时间：
2012-11-01
影响因子：
3.6
通讯作者：
Francis, Christopher A.
中科院分区：
文献类型：
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作者：
Mosier, Annika C.;Lund, Marie B.;Francis, Christopher A.
海洋和陆地生态系统中的氨氧化在氮和碳的循环中起着关键作用。最近的发现表明，氨氧化古菌（AOA）在这些系统中既丰富又多样，但对它们的生理学知之甚少。在这里，我们报告了一个新的低盐度型AOA富集从旧金山弗朗西斯科湾河口，ANODATUS亚硝化古菌limnia菌株SFB1的生理分析。N. limnia的生长速率比迄今为止描述的唯一纯AOA分离物Nitrosopumilus maritimus和Nitrososphaera viennensis EN 76慢，但生长速率与海洋AOA富集培养物的生长相当。当N. Limnia在低氧条件（顶部空间中5.5%氧）下生长。虽然N.在盐度为75%的海水中，泽蛙能够生长，但滞后时间较长，氨氧化为亚硝酸盐不完全，总体生长速率较慢。烯丙基硫脲（ATU）仅部分抑制N.已知浓度的Limnia完全抑制细菌氨氧化。利用电子显微镜，我们证实了鞭毛的存在所建议的各种鞭毛生物合成基因在N。湖沼基因组。我们证明了N. limnia是低盐度河口AOA生态类型的代表，其85%以上的蛋白质与其它沿海和河口宏基因组序列具有最高的同一性。我们的研究结果进一步强调了N. limnia和帮助解释其生态适应低盐度生态位。
Ammonia oxidation in marine and terrestrial ecosystems plays a pivotal role in the cycling of nitrogen and carbon. Recent discoveries have shown that ammonia-oxidizing archaea (AOA) are both abundant and diverse in these systems, yet very little is known about their physiology. Here we report a physiological analysis of a novel low-salinity-type AOA enriched from the San Francisco Bay estuary, Candidatus Nitrosoarchaeum limnia strain SFB1. N. limnia has a slower growth rate than Nitrosopumilus maritimus and Nitrososphaera viennensis EN76, the only pure AOA isolates described to date, but the growth rate is comparable to the growth of marine AOA enrichment cultures. The growth rate only slightly decreased when N. limnia was grown under lower-oxygen conditions (5.5 % oxygen in the headspace). Although N. limnia was capable of growth at 75 % of seawater salinity, there was a longer lag time, incomplete oxidation of ammonia to nitrite, and slower overall growth rate. Allylthiourea (ATU) only partially inhibited growth and ammonia oxidation by N. limnia at concentrations known to completely inhibit bacterial ammonia oxidation. Using electron microscopy, we confirmed the presence of flagella as suggested by various flagellar biosynthesis genes in the N. limnia genome. We demonstrate that N. limnia is representative of a low-salinity estuarine AOA ecotype and that more than 85 % of its proteins have highest identity to other coastal and estuarine metagenomic sequences. Our findings further highlight the physiology of N. limnia and help explain its ecological adaptation to low-salinity niches.