Padilla Cory C, Bristow Laura A, Sarode Neha, Garcia-Robledo Emilio, Gómez Ramírez Eddy, Benson Catherine R, Bourbonnais Annie, Altabet Mark A, Girguis Peter R, Thamdrup Bo, Stewart Frank J
School of Biology, Georgia Institute of Technology, Atlanta, GA, USA.
Department of Biology and Nordic Center for Earth Evolution (NordCEE), University of Southern Denmark, Odense, Denmark.
ISME J. 2016 Aug;10(8):2067-71. doi: 10.1038/ismej.2015.262. Epub 2016 Feb 26.
Bacteria of the NC10 phylum link anaerobic methane oxidation to nitrite denitrification through a unique O2-producing intra-aerobic methanotrophy pathway. A niche for NC10 in the pelagic ocean has not been confirmed. We show that NC10 bacteria are present and transcriptionally active in oceanic oxygen minimum zones (OMZs) off northern Mexico and Costa Rica. NC10 16S rRNA genes were detected at all sites, peaking in abundance in the anoxic zone with elevated nitrite and methane concentrations. Phylogenetic analysis of particulate methane monooxygenase genes further confirmed the presence of NC10. rRNA and mRNA transcripts assignable to NC10 peaked within the OMZ and included genes of the putative nitrite-dependent intra-aerobic pathway, with high representation of transcripts containing the unique motif structure of the nitric oxide (NO) reductase of NC10 bacteria, hypothesized to participate in O2-producing NO dismutation. These findings confirm pelagic OMZs as a niche for NC10, suggesting a role for this group in OMZ nitrogen, methane and oxygen cycling.
NC10门的细菌通过独特的产氧内好氧甲烷营养途径将厌氧甲烷氧化与亚硝酸盐反硝化作用联系起来。NC10在远洋海洋中的生态位尚未得到证实。我们发现，NC10细菌存在于墨西哥北部和哥斯达黎加沿海的海洋氧含量极小带（OMZ）中，并且具有转录活性。在所有位点均检测到NC10 16S rRNA基因，在亚硝酸盐和甲烷浓度升高的缺氧区丰度达到峰值。对颗粒性甲烷单加氧酶基因的系统发育分析进一步证实了NC10的存在。可归因于NC10的rRNA和mRNA转录本在OMZ内达到峰值，其中包括假定的亚硝酸盐依赖性内好氧途径的基因，含有NC10细菌一氧化氮（NO）还原酶独特基序结构的转录本占比很高，推测其参与产氧的NO歧化反应。这些发现证实了远洋OMZ是NC10的生态位，表明该类群在OMZ的氮、甲烷和氧循环中发挥作用。
