Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Ensenada, Mexico.
Instituto de Investigaciones Oceanológicas, Universidad Autónoma de Baja California, Ensenada, Mexico.
Chemosphere. 2024 Feb;349:140933. doi: 10.1016/j.chemosphere.2023.140933. Epub 2023 Dec 11.
Anaerobic ammonium oxidation, associated with both iron (Feammox) and manganese (Mnammox) reduction, is a microbial nitrogen (N) removal mechanism recently identified in natural ecosystems. Nevertheless, the spatial distributions of these non-canonical Anammox (NC-Anammox) pathways and their environmental drivers in subtidal coastal sediments are still unknown. Here, we determined the potential NC-Anammox rates and abundance of dissimilatory metal-reducing bacteria (Acidomicrobiaceae A6 and Geobacteraceae) at different horizons (0-20 cm at 5 cm intervals) of subtidal coastal sediments using the N isotope-tracing technique and molecular analyses. Sediments were collected across three sectors (inlet, transition, and inner) in a coastal lagoon system (Bahia de San Quintin, Mexico) dominated by seagrass meadows. The positive relationship between N production rates and dissimilatory Fe and Mn reduction provided evidence for Feammox's and Mnammox's co-occurrence. N loss through NC-Anammox was detected in subtidal sediments, with potential rates of 0.07-0.62 μg N g day. NC-Anammox process in vegetated sediments tended to be higher than those in adjacent unvegetated ones. NC-Anammox rates showed a subsurface peak (between 5 and 15 cm) in the vegetated sediments but decreased consistently with depth in the adjacent bare bottoms. Thus, the presence/absence of seagrasses and sediment characteristics, particularly the availability of organic carbon and microbiologically reducible Fe(III) and Mn(IV), affected the abundance of dissimilatory metal-reducing bacteria, which mediated NC-Anammox activity and the associated N removal. An annual loss of 32.31 ± 3.57 t N was estimated to be associated with Feammox and Mnammox within the investigated area, accounting for 2.8-4.7% of the gross total import of reactive N from the ocean into the Bahia de San Quintin. Taken as a whole, this study reveals the distribution patterns and controlling factors of the NC-Anammox pathways along a coastal lagoon system. It improves our understanding of the coupling between N and trace metal cycles in coastal environments.
厌氧氨氧化作用与铁（Feammox）和锰（Mnammox）还原有关，是最近在自然生态系统中发现的一种微生物氮（N）去除机制。然而，这些非典型厌氧氨氧化（NC-Anammox）途径的空间分布及其在潮下带沿海沉积物中的环境驱动因素仍不清楚。在这里，我们使用氮同位素示踪技术和分子分析，在墨西哥巴伊亚德圣金廷（Bahia de San Quintin）沿海泻湖系统的不同层次（0-20 cm，每隔 5 cm）确定了潮下带沿海沉积物中的潜在 NC-Anammox 速率和异化金属还原细菌（酸杆菌科 A6 和地杆菌科）的丰度。沉积物是在泻湖系统的三个扇区（入口、过渡和内部）采集的，该系统以海草草地为主。氮生产力与异化铁和锰还原之间的正相关关系为 Feammox 和 Mnammox 的共存提供了证据。在潮下带沉积物中检测到通过 NC-Anammox 的氮损失，潜在速率为 0.07-0.62 μg N g day。植被沉积物中的 NC-Anammox 过程往往高于相邻无植被沉积物中的过程。NC-Anammox 速率在植被沉积物中呈现出次表层峰值（在 5 至 15 cm 之间），但在相邻无底沉积物中随深度持续下降。因此，海草的存在/不存在和沉积物特征，特别是有机碳和微生物可还原的 Fe(III)和 Mn(IV)的可用性，影响了异化金属还原细菌的丰度，从而介导了 NC-Anammox 活性和相关的 N 去除。据估计，在所研究的区域内，与 Feammox 和 Mnammox 相关的氮损失每年为 32.31±3.57 t，占从海洋进入巴伊亚德圣金廷的总活性氮输入的 2.8-4.7%。总的来说，这项研究揭示了沿沿海泻湖系统的 NC-Anammox 途径的分布模式和控制因素。它提高了我们对沿海环境中氮和痕量金属循环耦合的理解。
