Alcamán-Arias María E, Cifuentes-Anticevic Jerónimo, Díez Beatriz, Testa Giovanni, Troncoso Macarena, Bello Estrella, Farías Laura
Departamento de Oceanografía, Universidad de Concepción, Concepción, Chile.
Center for Climate and Resilience Research (CR)2, Santiago, Chile.
Front Microbiol. 2022 Mar 25;13:821902. doi: 10.3389/fmicb.2022.821902. eCollection 2022.
Marine ammonia oxidizers that oxidize ammonium to nitrite are abundant in polar waters, especially during the winter in the deeper mixed-layer of West Antarctic Peninsula (WAP) waters. However, the activity and abundance of ammonia-oxidizers during the summer in surface coastal Antarctic waters remain unclear. In this study, the ammonia-oxidation rates, abundance and identity of ammonia-oxidizing bacteria (AOB) and archaea (AOA) were evaluated in the marine surface layer (to 30 m depth) in Chile Bay (Greenwich Island, WAP) over three consecutive late-summer periods (2017, 2018, and 2019). Ammonia-oxidation rates of 68.31 nmol N L day (2018) and 37.28 nmol N L day (2019) were detected from illuminated 2 m seawater incubations. However, high ammonia-oxidation rates between 267.75 and 109.38 nmol N L day were obtained under the dark condition at 30 m in 2018 and 2019, respectively. During the late-summer sampling periods both stratifying and mixing events occurring in the water column over short timescales (February-March). Metagenomic analysis of seven nitrogen cycle modules revealed the presence of ammonia-oxidizers, such as the Archaea and the Bacteria and , with AOA often being more abundant than AOB. However, quantification of specific A gene transcripts showed number of AOB being two orders of magnitude higher than AOA, with representing the most transcriptionally active AOB in the surface waters. Additionally, Nitrosopelagicus and , phylogenetically related to surface members of the NP-ε and NP-γ clades respectively, were the predominant AOA. Our findings expand the known distribution of ammonium-oxidizers to the marine surface layer, exposing their potential ecological role in supporting the marine Antarctic system during the productive summer periods.
将铵氧化为亚硝酸盐的海洋氨氧化菌在极地水域中大量存在，尤其是在南极半岛西部（WAP）水域较深混合层的冬季。然而，夏季南极沿海水域氨氧化菌的活性和丰度仍不清楚。在本研究中，连续三个夏末时期（2017年、2018年和2019年）对智利湾（格林威治岛，WAP）海洋表层（至30米深度）的氨氧化速率、氨氧化细菌（AOB）和古菌（AOA）的丰度及种类进行了评估。在2米光照海水培养中检测到2018年氨氧化速率为68.31 nmol N L⁻¹ d⁻¹，2019年为37.28 nmol N L⁻¹ d⁻¹。然而，在2018年和2019年分别于30米深度黑暗条件下获得了267.75至109.38 nmol N L⁻¹ d⁻¹的高氨氧化速率。在夏末采样期间，水柱在短时间尺度（2月至3月）内发生了分层和混合事件。对七个氮循环模块的宏基因组分析揭示了氨氧化菌的存在，如古菌 和细菌 以及 ，其中AOA通常比AOB更丰富。然而，特定A基因转录本的定量显示AOB数量比AOA高两个数量级， 是表层水中转录活性最高的AOB。此外，分别与NP - ε和NP - γ分支表层成员系统发育相关的 亚硝化浮游菌属和 是主要的AOA。我们的研究结果将铵氧化菌的已知分布扩展到了海洋表层，揭示了它们在生产力较高的夏季期间对南极海洋系统的潜在生态作用。
