College of Life Science, Qingdao Agricultural University , Qingdao, China.
CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Center for Ocean Mega-Science, Institute of Oceanology, Chinese Academy of Sciences , Qingdao, China.
mBio. 2023 Aug 31;14(4):e0011723. doi: 10.1128/mbio.00117-23. Epub 2023 Jul 6.
Chemoautotrophs within Campylobacterota, especially and , are abundant in the seawater-sediment interface of the Formosa cold seep in the South China Sea. However, the activity and function of Campylobacterota are unknown. In this study, the geochemical role of Campylobacterota in the Formosa cold seep was investigated with multiple means. Two members of and were isolated for the first time from deep-sea cold seep. These isolates are new chemoautotrophic species that can use molecular hydrogen as an energy source and CO as a sole carbon source. Comparative genomics identified an important hydrogen-oxidizing cluster in and . Metatranscriptomic analysis detected high expression of hydrogen-oxidizing gene in the RS, suggesting that H was likely an energy source in the cold seep. Genomic analysis indicated that the and isolates possess a truncated sulfur-oxidizing system, and metatranscriptomic analysis revealed that and with this genotype were active in the surface of RS and likely contributed to thiosulfate production. Furthermore, geochemical and analyses revealed sharply decreased nitrate concentration in the sediment-water interface due to microbial consumption. Consistently, the denitrification genes of and were highly expressed, suggesting an important contribution of these bacteria to nitrogen cycling. Overall, this study demonstrated that Campylobacterota played a significant role in the cycling of nitrogen and sulfur in a deep-sea cold seep. IMPORTANCE Chemoautotrophs within Campylobacterota, in particular and , are ubiquitous in deep-sea cold seeps and hydrothermal vents. However, to date, no or has been isolated from cold seeps, and the ecological roles of these bacteria in cold seeps remain to be investigated. In this study, we obtained two isolates of and from Formosa cold seep, South China Sea. Comparative genomics, metatranscriptomics, geochemical analysis, and experimental study indicated collectively that Campylobacterota played a significant part in nitrogen and sulfur cycling in cold seep and was the cause of thiosulfate accumulation and sharp reduction of nitrate level in the sediment-water interface. The findings of this study promoted our understanding of the function and ecological role of deep-sea Campylobacterota.
泉古菌门中的化能自养菌，特别是 和 ，在南海 Formosa 冷泉的海水-沉积物界面中大量存在。然而，泉古菌门的 活性和功能尚不清楚。在本研究中，采用多种方法研究了泉古菌门在 Formosa 冷泉中的地球化学作用。首次从深海冷泉中分离到 和 两个属的成员。这些分离株是新的化能自养种，可将分子氢作为能源，以 CO 作为唯一碳源。比较基因组学在 和 中鉴定出一个重要的氢氧化簇。宏转录组分析在 RS 中检测到高表达的氢氧化基因，表明 H 可能是冷泉中的能源。基因组分析表明， 和 分离株具有截短的硫氧化系统，宏转录组分析表明，具有这种基因型的 和 活跃于 RS 的表面，可能有助于硫代硫酸盐的产生。此外，地球化学和 分析表明，由于微生物的消耗，沉积物-水界面处的硝酸盐浓度急剧下降。一致地， 和 中的反硝化基因高度表达，表明这些细菌对氮循环有重要贡献。总的来说，这项研究表明，泉古菌在深海冷泉的氮和硫循环中发挥了重要作用。
