Cyanobacteria and cyanophage contributions to carbon and nitrogen cycling in an oligotrophic oxygen-deficient zone
Cyanobacteria and cyanophage contributions to carbon and nitrogen cycling in an oligotrophic oxygen-deficient zone
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DOI：
10.1038/s41396-019-0452-6
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发表时间：
2019-11-01
期刊：
影响因子：
11
通讯作者：
Rocap, Gabrielle
中科院分区：
文献类型：
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作者：
Fuchsman, Clara A.;Palevsky, Hilary I.;Rocap, Gabrielle
海洋氮损失的一半发生在缺氧区（ODZs）。生产性地表沃茨的有机物通量被认为是N-2生产的主要控制因素。在这里，我们调查了近海东部热带北太平洋（ETNP），其中二级叶绿素a最大值位于ODZ内。初级生产率和碳出口的混合层和生产力在初级叶绿素a最大值与贫营养沃茨是一致的。然而，沉积物陷阱的碳和氮通量增加105和150米之间，表明有机质生产内的ODZ。宏基因组和元蛋白质组特征表明，次生叶绿素a最大值是由于蓝藻原绿球藻，和许多光合作用和碳固定蛋白被检测到。化能自养氨氧化古菌和亚硝酸盐氧化剂Nitrospina和硝酸盐氧化还原酶的检测的存在下是一致的ODZ内的蓝藻产氧。蓝藻和噬藻体也存在于大颗粒（>30 μ m）和沉积物捕集器材料中。颗粒噬藻体与宿主的比例超过50，表明病毒有助于将蓝藻转化为下沉的有机物。硝酸盐还原和厌氧氨氧化蛋白的检测，与以前报道的N-2生产一致。我们认为，在ODZ的本地有机质生产有助于N-2生产在海上ETNP。
Up to half of marine N losses occur in oxygen-deficient zones (ODZs). Organic matter flux from productive surface waters is considered a primary control on N-2 production. Here we investigate the offshore Eastern Tropical North Pacific (ETNP) where a secondary chlorophyll a maximum resides within the ODZ. Rates of primary production and carbon export from the mixed layer and productivity in the primary chlorophyll a maximum were consistent with oligotrophic waters. However, sediment trap carbon and nitrogen fluxes increased between 105 and 150 m, indicating organic matter production within the ODZ. Metagenomic and metaproteomic characterization indicated that the secondary chlorophyll a maximum was attributable to the cyanobacterium Prochlorococcus, and numerous photosynthesis and carbon fixation proteins were detected. The presence of chemoautotrophic ammonia-oxidizing archaea and the nitrite oxidizer Nitrospina and detection of nitrate oxidoreductase was consistent with cyanobacterial oxygen production within the ODZ. Cyanobacteria and cyanophage were also present on large (>30 mu m) particles and in sediment trap material. Particle cyanophage-to-host ratio exceeded 50, suggesting that viruses help convert cyanobacteria into sinking organic matter. Nitrate reduction and anammox proteins were detected, congruent with previously reported N-2 production. We suggest that autochthonous organic matter production within the ODZ contributes to N-2 production in the offshore ETNP.