Geomicrobiology, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany.
Microbial Ecology, Center for Applied Geosciences, University of Tübingen, Tübingen, Germany.
Sci Rep. 2019 Jul 31;9(1):10691. doi: 10.1038/s41598-019-47172-x.
Nitrous oxide (NO) is a potent greenhouse gas that also contributes to stratospheric ozone depletion. Besides microbial denitrification, abiotic nitrite reduction by Fe(II) (chemodenitrification) has the potential to be an important source of NO. Here, using microcosms, we quantified NO formation in coastal marine sediments under typical summer temperatures. Comparison between gamma-radiated and microbially-active microcosm experiments revealed that at least 15-25% of total NO formation was caused by chemodenitrification, whereas 75-85% of total NO was potentially produced by microbial N-transformation processes. An increase in (chemo)denitrification-based NO formation and associated Fe(II) oxidation caused an upregulation of NO reductase (typical nosZ) genes and a distinct community shift to potential Fe(III)-reducers (Arcobacter), Fe(II)-oxidizers (Sulfurimonas), and nitrate/nitrite-reducing microorganisms (Marinobacter). Our study suggests that chemodenitrification contributes substantially to NO formation from marine sediments and significantly influences the N- and Fe-cycling microbial community.
一氧化二氮（NO）是一种强效温室气体，也是平流层臭氧消耗的原因之一。除了微生物脱氮作用外，Fe(II)的非生物亚硝酸盐还原（化学反硝化）有可能成为 NO 的一个重要来源。在这里，我们使用微宇宙实验在典型夏季温度下定量研究了沿海海洋沉积物中 NO 的形成。γ辐射和微生物活性微宇宙实验的比较表明，至少有 15-25%的总 NO 形成是由化学反硝化作用引起的，而 75-85%的总 NO 可能是由微生物氮转化过程产生的。（化学）反硝化作用引起的 NO 形成和相关的 Fe(II)氧化增加导致了 NO 还原酶（典型的 nosZ）基因的上调以及潜在的 Fe(III)还原剂（Arcobacter）、Fe(II)氧化菌（Sulfurimonas）和硝酸盐/亚硝酸盐还原微生物（Marinobacter）的明显群落转移。我们的研究表明，化学反硝化作用对海洋沉积物中 NO 的形成有很大贡献，并显著影响氮和铁循环微生物群落。
