Aerobic nitrite oxidation in marine environments plays a key role in the nitrification process. Marine bacteria involved in this nitrate‐producing process have however been seldom studied compared with the ammonia‐oxidizing community. Here, we report for the first time the community structure of aerobic nitrite‐oxidizing bacteria (NOB) in the seasonal upwelling and oxygen‐deficient area off Central Chile. Analysis of 16S rRNA by tag pyrosequencing was combined with specific quantitative polymerase chain reaction (qPCR) and reverse transcription qPCR in summer and wintertime. Nitrospina‐like bacteria were the only known NOB detected by means of pyrosequencing between 30 and 80 m depth, accounting for up to 5% of total bacteria. This guild was represented by 11 and 7 operational taxonomic units (97% cut‐off) in winter and summertime respectively. Nitrospina‐like bacteria were phylogenetically related to sequences retrieved from coastal upwelling, oxygen minimum zones and deep‐sea environments. This group was also detected by qPCR with abundances that increased with depth throughout the water column. Importantly, Nitrospina from surface layers showed low abundances but high 16S rRNA : rDNA ratios and mainly in summertime. Overall, our results highlight the seasonal variability between the structure and physiological state of this community and suggest a significant role of Nitrospina in the nitrogen cycle of seasonal upwelling areas.

中文翻译：

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在南太平洋东部（智利中部〜36°S）的季节性上升区，类固氮菌是亚硝酸盐氧化的主要驱动力。

海洋环境中的好氧亚硝酸盐氧化在硝化过程中起关键作用。然而，与氨氧化社区相比，很少研究涉及该硝酸盐生产过程的海洋细菌。在这里，我们首次报告了智利中部附近季节性上升流和缺氧地区好氧亚硝酸盐氧化细菌（NOB）的群落结构。在夏季和冬季，通过标签焦磷酸测序对16S rRNA的分析与特异性定量聚合酶链反应（qPCR）和逆转录qPCR相结合。ñ itrospina类细菌是通过焦磷酸测序法在30至80 m深度之间检测到的唯一已知NOB，占细菌总数的5％。该行会在冬季和夏季分别由11个和7个操作分类单位（截止97％）代表。Ñ itrospina样细菌系统发生学上与从沿海涌，最低含氧区和深海环境检索序列。还通过qPCR检测到该组，其丰度随整个水柱的深度而增加。重要的是，ñ itrospina从表层发现的丰度较低，但16S rRNA：rDNA比例较高，且主要在夏季。总的来说，我们的研究结果强调结构和这个社会的生理状态之间的季节性变化和建议的显著作用ñ itrospina季节性上升流区的氮循环。