Deep-sea methane seep sediments in the Okhotsk Sea sustain diverse and abundant anammox bacteria

Abstract

Marginal sea methane seep sediments sustain highly productive chemosynthetic ecosystems and are hotspots of intense biogeochemical cycling. Rich methane supply stimulates rapid microbial consumption of oxygen; these systems are thus usually hypoxic to anoxic. This and reported evidence for resident nitrogen fixation suggest the presence of an anaerobic ammonium-oxidizing (anammox) bacterial community in methane seep sediments. To test this hypothesis, we employed detection of genes encoding 16S rRNA gene and hydrazine dehydrogenase (hzo) to investigate the structure, abundance and distribution of the anammox bacterial community in the methane seep sediments of the Okhotsk Sea. Diverse complements of Candidatus Scalindua-related 16S rRNA and hzo gene sequences were obtained. Most of the deep-sea sites harbored abundant hzo genes with copy numbers as high as 10(7) g(-1) sediment. In general, anammox bacterial signatures were significantly more abundant in the deep-water sediments. Sediment porewater NO3-, NOx- (i.e. NO3- + NO2-), NOx-/NH4+ and sediment silt content correlated with in situ distribution patterns of anammox bacterial marker genes, likely because they determine anammox substrate availability and sediment geochemistry, respectively. The abundance and distribution of anammox bacterial gene markers indicate a potentially significant contribution of anammox bacteria to the marine N cycle in the deep-sea methane seep sediments.

An overlooked nitrogen loss linked to anaerobic ammonium oxidation in estuarine sediments in China

“…Heterotrophic denitrification was considered to be the only known pathway for the loss of fixed nitrogen to the atmosphere for decades until the discovery of anammox bacteria in a wastewater treatment plant (Mulder et al 1995). Subsequently, anammox bacteria were detected with broad biogeographic distribution in various natural ecosystems, including marine sediments (Thamdrup and Dalsgaard 2002;Trimmer and Nicholls 2009;Brabandere et al 2014;Shao et al 2014;Dang et al 2016), estuarine sediments (Dale et al 2009;Dang et al 2010;Li et al 2011;Wang et al 2012a, b;Dang et al 2013), and paddy soils (Zhu et al 2011;Nie et al 2015;Yang et al 2015). The relative contribution of anammox to dinitrogen production can vary widely, with >80% of total N 2 production observed in the eastern tropical South Pacific oxygen minimum zone (OMZ) off the coast of northern Chile (Brabandere et al 2014).…”

Depth-specific distribution and importance of nitrite-dependent anaerobic ammonium and methane-oxidising bacteria in an urban wetland

“…So far, there are five genera of anammox bacteria have been described, including Candidatus Brocadia (Strous et al, 1999;Kartal et al, 2008;Hu et al, 2010), Candidatus Kuenenia (Schmid et al, 2000), Candidatus Scalindua (Kuypers et al, 2003;Schmid et al, 2003;Woebken et al, 2008;van de Vossenberg et al, 2013), Candidatus Anammoxoglobus (Kartal et al, 2007) and Candidatus Jettenia (Quan et al, 2008;Hu et al, 2012). Until now, anammox bacteria have been found in various marine ecosystems Hu et al, 2012a;Shao et al, 2014), freshwater ecosystems (Hu et al, 2012b;Wenk et al, 2013;Ding et al, 2014) and terrestrial ecosystems (Humbert et al, 2010;Shen et al, 2013).…”

Reviews and syntheses: Processes and functional genes involved in nitrogen cycling in marine environments

“…Anammox bacteria are also present and active in hydrothermal vent areas, such as those in the Mid-Atlantic Ridge, where Ca. Kuenenia was found at 300°C (Byrne et al, 2009), and the Okhotsk Sea, where hzo genes are highly abundant (Shao et al, 2014). A study in the Guaymas Basin revealed that Ca.…”