Zhao Rui, Babbin Andrew R, Roerdink Desiree L, Thorseth Ingunn H, Jørgensen Steffen L
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.
Centre for Deep Sea Research, Department of Earth Science, University of Bergen, Bergen, 5007, Norway.
ISME Commun. 2023 Mar 29;3(1):26. doi: 10.1038/s43705-023-00230-y.
By consuming ammonium and nitrite, anammox bacteria form an important functional guild in nitrogen cycling in many environments, including marine sediments. However, their distribution and impact on the important substrate nitrite has not been well characterized. Here we combined biogeochemical, microbiological, and genomic approaches to study anammox bacteria and other nitrogen cycling groups in two sediment cores retrieved from the Arctic Mid-Ocean Ridge (AMOR). We observed nitrite accumulation in these cores, a phenomenon also recorded at 28 other marine sediment sites and in analogous aquatic environments. The nitrite maximum coincides with reduced abundance of anammox bacteria. Anammox bacterial abundances were at least one order of magnitude higher than those of nitrite reducers and the anammox abundance maxima were detected in the layers above and below the nitrite maximum. Nitrite accumulation in the two AMOR cores co-occurs with a niche partitioning between two anammox bacterial families (Candidatus Bathyanammoxibiaceae and Candidatus Scalinduaceae), likely dependent on ammonium availability. Through reconstructing and comparing the dominant anammox genomes (Ca. Bathyanammoxibius amoris and Ca. Scalindua sediminis), we revealed that Ca. B. amoris has fewer high-affinity ammonium transporters than Ca. S. sediminis and lacks the capacity to access alternative substrates and/or energy sources such as urea and cyanate. These features may restrict Ca. Bathyanammoxibiaceae to conditions of higher ammonium concentrations. These findings improve our understanding about nitrogen cycling in marine sediments by revealing coincident nitrite accumulation and niche partitioning of anammox bacteria.
通过消耗铵和亚硝酸盐，厌氧氨氧化细菌在包括海洋沉积物在内的许多环境的氮循环中形成了一个重要的功能群落。然而，它们的分布以及对重要底物亚硝酸盐的影响尚未得到充分表征。在这里，我们结合生物地球化学、微生物学和基因组学方法，研究了从北极中洋脊（AMOR）获取的两个沉积物岩芯中的厌氧氨氧化细菌和其他氮循环菌群。我们在这些岩芯中观察到亚硝酸盐积累，这一现象在其他28个海洋沉积物站点以及类似的水生环境中也有记录。亚硝酸盐最大值与厌氧氨氧化细菌丰度的降低相吻合。厌氧氨氧化细菌的丰度比亚硝酸盐还原菌至少高一个数量级，并且在亚硝酸盐最大值之上和之下的层中检测到厌氧氨氧化丰度最大值。两个AMOR岩芯中的亚硝酸盐积累与两个厌氧氨氧化细菌家族（“Candidatus Bathyanammoxibiaceae”和“Candidatus Scalinduaceae”）之间的生态位划分同时出现，这可能取决于铵的可用性。通过重建和比较占主导地位的厌氧氨氧化基因组（“Ca. Bathyanammoxibius amoris”和“Ca. Scalindua sediminis”），我们发现“Ca. B. amoris”的高亲和力铵转运蛋白比“Ca. S. sediminis”少，并且缺乏获取替代底物和/或能源（如尿素和氰酸盐）的能力。这些特征可能将“Ca. Bathyanammoxibiaceae”限制在铵浓度较高的条件下。这些发现通过揭示亚硝酸盐积累与厌氧氨氧化细菌的生态位划分的同时出现，提高了我们对海洋沉积物中氮循环的理解。
