Shao Bo, Xie Yuan-Guo, Zhang Long, Ruan Yang, Liang Bin, Zhang Ruochen, Xu Xijun, Wang Wei, Lin Zhengda, Pei Xuanyuan, Wang Xueting, Zhao Lei, Zhou Xu, Wu Xiaohui, Xing Defeng, Wang Aijie, Lee Duu-Jong, Ren Nanqi, Canfield Donald E, Hedlund Brian P, Hua Zheng-Shuang, Chen Chuan
State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, PR China.
Chinese Academy of Sciences Key Laboratory of Urban Pollutant Conversion, Department of Environmental Science and Engineering, University of Science and Technology of China, Hefei, 230026, PR China.
Nat Commun. 2025 Jan 31;16(1):1202. doi: 10.1038/s41467-025-56588-1.
Heterotrophic denitrifiers play crucial roles in global carbon and nitrogen cycling. However, their inability to oxidize sulfide renders them vulnerable to this toxic molecule, which inhibits the key enzymatic reaction responsible for reducing nitrous oxide (NO), thereby raising greenhouse gas emissions. Here, we applied microcosm incubations, community-isotope-corrected DNA stable-isotope probing, and metagenomics to characterize a cohort of heterotrophic denitrifiers in estuarine sediments that thrive by coupling sulfur oxidation with denitrification through chemolithoheterotrophic metabolism. Remarkably, ecophysiology experiments from enrichments demonstrate that such heterotrophs expedite denitrification with sulfur acting as alternative electron sources and substantially curtail NO emissions in both organic-rich and organic-limited environments. Their flexible, non-sulfur-dependent physiology may confer competitive advantages over conventional heterotrophic denitrifiers in detoxifying sulfide, adapting to organic matter fluctuations, and mitigating greenhouse gas emissions. Our study provides insights into the ecological role of heterotrophic denitrifiers in microbial communities with implications for sulfur cycling and climate change.
异养反硝化菌在全球碳氮循环中发挥着关键作用。然而，它们无法氧化硫化物，这使得它们容易受到这种有毒分子的影响，该分子会抑制负责还原一氧化二氮（N₂O）的关键酶促反应，从而增加温室气体排放。在这里，我们应用了微宇宙培养、群落同位素校正的DNA稳定同位素探测和宏基因组学来表征河口沉积物中的一组异养反硝化菌，它们通过化学无机异养代谢将硫氧化与反硝化作用耦合，从而茁壮成长。值得注意的是，富集培养的生态生理学实验表明，这类异养菌以硫作为替代电子源加速反硝化作用，并在富含有机物和有机物有限的环境中大幅减少N₂O排放。它们灵活的、不依赖硫的生理特性可能在解毒硫化物、适应有机物波动和减少温室气体排放方面比传统异养反硝化菌具有竞争优势。我们的研究深入了解了异养反硝化菌在微生物群落中的生态作用，对硫循环和气候变化具有重要意义。
