Novel Alphaproteobacteria transcribe genes for nitric oxide transformation at high levels in a marine oxygen-deficient zone
Novel Alphaproteobacteria transcribe genes for nitric oxide transformation at high levels in a marine oxygen-deficient zone
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DOI：
10.1128/aem.02099-23
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发表时间：
2024-03-06
影响因子：
4.4
通讯作者：
Glass，Jennifer B.
中科院分区：
文献类型：
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作者：
Elbon，Claire E.;Stewart，Frank J.;Glass，Jennifer B.
海洋缺氧区（ODZs）是海洋的一部分，主要通过反硝化和厌氧氨氧化发生强烈的氮损失。尽管经过几十年的研究，在臭氧消耗区催化氮损失的微生物的身份仍在阐明。有趣的是，在缺氧核心的ODZs中，已经报道了与来自Methylomirabilota的一氧化氮歧化酶（nod）基因相同家族的基因的高转录。在这里，我们表明，最丰富的转录的基因在东热带北太平洋ODZ属于一个新的秩序（UBA 11136）的Alphaproteobacteria，而不是甲基omirabilota如先前所假设的。Gammaproteobacteria和Planctomycetia也transscribenod，但在较低的相对丰度比UBA 11136在上ODZ。转录节点的α-变形菌可能使用甲醛和甲酸盐作为有氧呼吸的电子来源，额外的电子可能来自硫化物氧化。他们还转录多血红素细胞色素（这里命名为ptd）基因的一个假定的孔蛋白细胞色素蛋白复合物的未知功能，可能参与细胞外电子转移。有氧呼吸所需的分子氧可能来源于一氧化氮歧化，通过隐蔽的氧循环。我们的研究结果牵连Alphaproteobacteria为了UBA 11136作为一个显着的球员在海洋氮的损失，并强调他们的潜力在一个碳，氮，硫代谢在ODZs.IMPORTANCEIn海洋缺氧区（ODZs），微生物转化为气态氮，一氧化氮作为关键中间体。东热带北太平洋包含世界上最大的臭氧消耗区，但转化一氧化氮的微生物的身份仍然未知。在这里，我们表明，高度转录的一氧化氮歧化酶（NOD）基因属于Alphaproteobacteria的新订单UBA 11136，缺乏培养的菌株。这些Alphaproteobacteria有氧呼吸的证据，使用氧可能来源于一氧化氮歧化酶，并拥有一种新的孔蛋白-细胞色素蛋白复合物与未知的功能。γ-变形菌和转录浮菌处于较低水平。我们的研究结果指出了微生物介导海洋氮损失的关键步骤，并揭示了海洋Alphaproteobacteria意想不到的预测代谢。
Marine oxygen-deficient zones (ODZs) are portions of the ocean where intense nitrogen loss occurs primarily via denitrification and anammox. Despite many decades of study, the identity of the microbes that catalyze nitrogen loss in ODZs is still being elucidated. Intriguingly, high transcription of genes in the same family as the nitric oxide dismutase (nod) gene from Methylomirabilota has been reported in the anoxic core of ODZs. Here, we show that the most abundantly transcribednodgenes in the Eastern Tropical North Pacific ODZ belong to a new order (UBA11136) of Alphaproteobacteria,rather than Methylomirabilota as previously assumed. Gammaproteobacteria and Planctomycetia also transcribenod, but at lower relative abundance than UBA11136 in the upper ODZ. Thenod-transcribing Alphaproteobacteria likely use formaldehyde and formate as a source of electrons for aerobic respiration, with additional electrons possibly from sulfide oxidation. They also transcribe multiheme cytochrome (here namedptd) genes for a putative porin-cytochrome protein complex of unknown function, potentially involved in extracellular electron transfer. Molecular oxygen for aerobic respiration may originate from nitric oxide dismutation via cryptic oxygen cycling. Our results implicate Alphaproteobacteria order UBA11136 as a significant player in marine nitrogen loss and highlight their potential in one-carbon, nitrogen, and sulfur metabolism in ODZs.IMPORTANCEIn marine oxygen-deficient zones (ODZs), microbes transform bioavailable nitrogen to gaseous nitrogen, with nitric oxide as a key intermediate. The Eastern Tropical North Pacific contains the world’s largest ODZ, but the identity of the microbes transforming nitric oxide remains unknown. Here, we show that highly transcribed nitric oxide dismutase (nod) genes belong to Alphaproteobacteria of the novel order UBA11136, which lacks cultivated isolates. These Alphaproteobacteria show evidence for aerobic respiration, using oxygen potentially sourced from nitric oxide dismutase, and possess a novel porin-cytochrome protein complex with unknown function. Gammaproteobacteria and Planctomycetia transcribenodat lower levels. Our results pinpoint the microbes mediating a key step in marine nitrogen loss and reveal an unexpected predicted metabolism for marine Alphaproteobacteria.