Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA.
ISME J. 2011 Nov;5(11):1796-808. doi: 10.1038/ismej.2011.58. Epub 2011 May 12.
Archaeal genes for ammonia oxidation are widespread in the marine environment, but direct physiological evidence for ammonia oxidation by marine archaea is limited. We report the enrichment and characterization of three strains of pelagic ammonia-oxidizing archaea (AOA) from the North Pacific Ocean that have been maintained in laboratory culture for over 3 years. Phylogenetic analyses indicate the three strains belong to a previously identified clade of water column-associated AOA and possess 16S ribosomal RNA genes and ammonia monooxygenase subunit a (amoA) genes highly similar (98-99% identity) to those recovered in DNA and complementary DNA clone libraries from the open ocean. The strains grow in natural seawater-based liquid medium while stoichiometrically converting ammonia (NH(3)) to nitrite (NO(2)(-)). Ammonia oxidation by the enrichments is only partially inhibited by allylthiourea at concentrations known to completely inhibit cultivated ammonia-oxidizing bacteria. The three strains were used to determine the nitrogen stable isotope effect ((15)ɛ(NH3)) during archaeal ammonia oxidation, an important parameter for interpreting stable isotope ratios in the environment. Archaeal (15)ɛ(NH3) ranged from 13‰ to 41‰, within the range of that previously reported for ammonia-oxidizing bacteria. Despite low amino acid identity between the archaeal and bacterial Amo proteins, their functional diversity as captured by (15)ɛ(NH3) is similar.
海洋环境中广泛存在能够进行氨氧化作用的古菌基因，但有关海洋古菌进行氨氧化作用的直接生理学证据十分有限。我们报告了从北太平洋中富集并分离得到的 3 株海洋氨氧化古菌（AOA），并在实验室中对它们进行了超过 3 年的培养。系统发育分析表明，这 3 株菌属于以前在水柱相关 AOA 中鉴定到的一个分支，并且它们的 16S rRNA 基因和氨单加氧酶亚基 a（amoA）基因与从开阔海域的 DNA 和 cDNA 克隆文库中获得的基因高度相似（同源性 98-99%）。这些菌株在天然海水基础的液体培养基中生长，同时将氨（NH3）化学计量地转化为亚硝酸盐（NO2(-)）。在已知能够完全抑制培养的氨氧化细菌的浓度下，添加烯丙基硫脲仅能部分抑制富集物中的氨氧化作用。利用这 3 株菌，我们确定了古菌氨氧化过程中的氮稳定同位素效应（(15)ɛ(NH3)），这是解释环境中稳定同位素比值的一个重要参数。古菌的(15)ɛ(NH3)值范围为 13‰至 41‰，与以前报道的氨氧化细菌的(15)ɛ(NH3)值范围相吻合。尽管古菌的氨单加氧酶与细菌的氨单加氧酶蛋白的氨基酸序列相似性较低，但它们的功能多样性（如通过(15)ɛ(NH3)来体现）是相似的。
