中国南海北部陆坡沉积物古菌多样性及丰度分析

The diversity and richness of archaea in the northern continental slope of South China Sea

摘要:

【目的】海洋沉积物中的古菌在全球生物地球化学循环中充当重要的角色，深入了解沉积物中古菌群落的结构及功能特征是探究海洋沉积物中古菌参与生物地球化学循环和生态学功能的基础。【方法】采用高通量测序技术，分别对南海北部陆坡不同海域(东部，西部和神狐海域的7个站位)沉积物中古菌16S rRNA基因进行Illumina Miseq测序。【结果】中国南海北部陆坡沉积物中古菌的主要门类是Bathyarchaeota、Thermoplasmata、Woesearchaeota (DHVEG-6)、Thaumarchaeota (Marine Group I)、Lokiarchaeota和Marine Hydrothermal Vent Group (MHVG)，还存在少量的AK8、Marine Benthic Group A和Terrestrial Hot Spring Crenarchaeota Group (THSCG)等。在潜在水合物区沉积物中还发现了甲烷代谢相关古菌(Anaerobic methanotrophic archaea，ANME)类群，主要为ANME-1、ANME-2ab和ANME-2c等。甲烷代谢古菌的分布特征也从甲烷代谢保守功能基因mcrA (methyl coenzyme-M reductase A)的扩增中得到了验证。利用定量PCR对南海沉积物中的细菌、古菌的16S rRNA基因和mcrA基因进行了定量，发现细菌16S rRNA基因拷贝数为105?107 copies/g (湿重)，古菌16S rRNA基因拷贝数为105?106 copies/g (湿重)，潜在水合物区mcrA基因拷贝数为103?105 copies/g (湿重)。【结论】揭示了中国南海北部陆坡沉积物中具有丰富的微生物资源，其中古菌种类多样且丰度较高，同时发现冷泉特征古菌群落，为深入认识和理解南海沉积物中微生物丰度和古菌多样性，以及解析古菌地球化学功能奠定基础。

关键词:中国南海北部陆坡，沉积物，古菌多样性，厌氧甲烷古菌，深古菌门，mcrA基因

Abstract:

[Objective] The archaea are recognized as key players participating in the global biogeochemical cycles in marine sediments. The knowledge upon community structure and metabolic functions of archaea is the basis to understand their potential contributions on the biogeochemical cycles globally. [Methods] Archaeal diversity in the sediments of three areas at the northern continental slope of SCS was surveyed using high-through sequencing for 16S rRNA gene. [Results] The major archaeal groups in the sediments was found to include Bathyarchaeota, Thermoplasmata, Woesearchaeota (DHVEG-6), Thaumarchaeota (Marine Group I), Lokiarchaeota and Marine Hydrothermal Vent Group (MHVG), also with low abundant of AK8, Marine Benthic Group A and Terrestrial Hot Spring Crenarchaeota Group (THSCG). Anaerobic methane oxidation (AOM) microbes (Anaerobic methanotrophic archaea, ANME), mainly ANME-1, ANME-2ab and ANME-2c were also found in the potential gas hydrate zone. Methyl coenzyme-M reductase alpha subunit (mcrA) gene, which encodes the key enzyme in methane metabolism, was also recovered from these sites, implying potentially active methane cycling. Quantitative PCR results showed that the abundance for bacterial 16S rRNA gene, archaeal 16S rRNA gene and mcrA gene were 105?107 copies/g (wet weight), 105?106 copies/g (wet weight) and 103?105 copies/g (wet weight), respectively. [Conclusion] These results revealed high diversity of archaea and rich microbial recourses in SCS sediments, layed the foundation for further analysis and understanding of archaeal mediated carbon cycling in the sediments of SCS.

Key words:Northern continental slope of South China Sea (SCS), Sediments, Archaeal diversity, Anaerobic methanotrophic archaea, Bathyarchaeota, mcrA gene