Department of Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea.
Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI, USA.
ISME J. 2018 Aug;12(8):2086-2089. doi: 10.1038/s41396-017-0022-8. Epub 2018 Jan 12.
Methanotrophs synthesize methanobactin, a secondary metabolite that binds copper with an unprecedentedly high affinity. Such a strategy may provide methanotrophs a "copper monopoly" that can inhibit the activity of copper-containing enzymes of other microbes, e.g., copper-dependent NO reductases. Here, we show that methanobactin from Methylosinus trichosporium OB3b inhibited NO reduction in denitrifiers. When Pseudomonas stutzeri DCP-Ps1 was incubated in cocultures with M. trichosporium OB3b or with purified methanobactin from M. trichosporium OB3b, stoichiometric NO production was observed from NO reduction, whereas no significant NO accumulation was observed in cocultures with a mutant defective in methanobactin production. Copper uptake by P. stutzeri DCP-Ps1 was inhibited by the presence of purified methanobactin, leading to a significant downregulation of nosZ transcription. Similar findings were observed with three other denitrifier strains. These results suggest that in situ stimulation of methanotrophs can inadvertently increase NO emissions, with the potential for increasing net greenhouse gas emissions.
产甲烷菌合成甲烷菌素，这是一种具有空前高亲和力结合铜的次生代谢物。这种策略可能为产甲烷菌提供了一种“铜垄断”，可以抑制其他微生物（如铜依赖型一氧化氮还原酶）含铜酶的活性。在这里，我们表明来自 Methylosinus trichosporium OB3b 的甲烷菌素抑制了反硝化菌的 NO 还原。当 Pseudomonas stutzeri DCP-Ps1 与 M. trichosporium OB3b 共培养或与从 M. trichosporium OB3b 中纯化的甲烷菌素共培养时，从 NO 还原中观察到了等摩尔的 NO 产生，而在与产甲烷菌素缺陷突变体的共培养中则没有观察到显著的 NO 积累。存在纯化的甲烷菌素时，P. stutzeri DCP-Ps1 的铜摄取受到抑制，导致 nosZ 转录显著下调。在其他三个反硝化菌菌株中也观察到了类似的发现。这些结果表明，产甲烷菌的原位刺激可能会无意中增加 NO 的排放，从而有可能增加净温室气体排放。
