Chemoautotrophic Thermodesulfobacteriota as a key genomic potential group in the hypoxic diazotrophic community of the Changjiang (Yangtze River) estuary

作者：Mengjia Zhang, Yuanli Zhu, Zhenhao Sun, Bin Wang, Jianfang Chen, Feng Zhou, Jiangning Zeng, Meng Li, Dayu Zou, Zhibing Jiang · 发表于：Frontiers in Microbiology · 年份：2025 · DOI：10.3389/fmicb.2025.1671267 · 被引用次数：1 · 研究领域：Microbial Community Ecology and Physiology、Marine and coastal ecosystems、Aquatic Ecosystems and Phytoplankton Dynamics

Coastal hypoxia, intensified by global warming and eutrophication, profoundly affects marine nitrogen cycling. However, its impact on diazotrophic communities in large river estuaries remains poorly understood. During an unprecedented hypoxia event (minimum dissolved oxygen at 2.70 μmol L −1 ) in August 2016 in the Changjiang Estuary, we sampled across a dissolved oxygen (DO) gradient spanning hypoxic and non-hypoxic waters. Using nifH gene amplicon sequencing, metagenomic binning, and multivariate statistical analyses, we found that higher diazotrophic biodiversity was observed in hypoxia zone, with non-cyanobacterial diazotrophs dominating the communities. The phylum Thermodesulfobacteriota (with relative abundance of 58.93% totally) exhibited significant hypoxia-specific enrichment. LEfSe analysis identified Thermodesulfobacteriota as potential hypoxia biomarkers, while network analysis revealed their keystone role, representing 68.6% of highly connected nodes. Environmental drivers, including low DO concentrations (7.50–61.88 μmol L −1 in hypoxic vs. 66.56–255.63 μmol L −1 in non-hypoxic zones), elevated salinity (30.67–34.50), increased dissolved reactive phosphorus (0.39–1.26 μmol L −1 ), and nitrate depletion (0.30–22.50 μmol L −1 ), collectively created favorable conditions for the development of the observed diazotrophic community under hypoxia. Metagenomic analysis revealed a hypoxia-driven increase in nifH gene abundance, with nifH -carrying metagenome-assembled ge...