División de Ciencias Ambientales, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), 78216, San Luis Potosí, SLP, Mexico.
Centro de Investigación en Alimentación y Desarrollo (CIAD-Mazatlán), 82100, Sinaloa, Mexico.
Biodegradation. 2018 Oct;29(5):429-442. doi: 10.1007/s10532-018-9839-8. Epub 2018 Jun 11.
Availability of fixed nitrogen is a pivotal driver on primary productivity in the oceans, thus the identification of key processes triggering nitrogen losses from these ecosystems is of major importance as they affect ecosystems function and consequently global biogeochemical cycles. Denitrification and anaerobic ammonium oxidation coupled to nitrite reduction (Anammox) are the only identified marine sinks for fixed nitrogen. The present study provides evidence indicating that anaerobic ammonium oxidation coupled to the reduction of sulfate, the most abundant electron acceptor present in the oceans, prevails in marine sediments. Tracer analysis with N-ammonium revealed that this microbial process, here introduced as Sulfammox, accounts for up to 5 μg N produced g day in sediments collected from the eastern tropical North Pacific coast. Raman and X-ray diffraction spectroscopies revealed that elemental sulfur and sphalerite (ZnFeS) were produced, besides free sulfide, during the course of Sulfammox. Anaerobic ammonium oxidation linked to Fe(III) reduction (Feammox) was also observed in the same marine sediments accounting for up to 2 μg N produced g day. Taxonomic characterization, based on 16S rRNA gene sequencing, of marine sediments performing the Sulfammox and Feammox processes revealed the microbial members potentially involved. These novel nitrogen sinks may significantly fuel nitrogen loss in marine environments. These findings suggest that the interconnections among the oceanic biogeochemical cycles of N, S and Fe are much more complex than previously considered.
固定氮的可用性是海洋初级生产力的关键驱动因素，因此，确定引发这些生态系统氮损失的关键过程非常重要，因为它们会影响生态系统的功能，进而影响全球生物地球化学循环。反硝化作用和厌氧氨氧化耦合亚硝酸盐还原（Anammox）是固定氮在海洋中的唯一已知汇。本研究提供了证据表明，在海洋沉积物中，与硫酸盐还原偶联的厌氧氨氧化作用（最丰富的电子受体）占主导地位。用 N-铵进行示踪分析表明，这种微生物过程，本文中称为 Sulfammox，在从东热带北太平洋海岸采集的沉积物中，最高可产生 5μgN/g·天。拉曼和 X 射线衍射光谱分析表明，在 Sulfammox 过程中，除了游离硫化物外，还产生了元素硫和闪锌矿（ZnFeS）。在同一海洋沉积物中也观察到与 Fe(III)还原偶联的厌氧氨氧化作用（Feammox），最高可产生 2μgN/g·天。基于 16S rRNA 基因测序对进行 Sulfammox 和 Feammox 过程的海洋沉积物进行的分类特征分析揭示了潜在涉及的微生物成员。这些新的氮汇可能会显著促进海洋环境中的氮损失。这些发现表明，海洋氮、硫和铁生物地球化学循环之间的相互联系比以前认为的要复杂得多。
