Biogeographical distribution and diversity of microbes in methane hydrate-bearing deep marine sediments on the Pacific Ocean Margin

Abstract

The deep subseafloor biosphere is among the least-understood habitats on Earth, even though the huge microbial biomass therein plays an important role for potential long-term controls on global biogeochemical cycles. We report here the vertical and geographical distribution of microbes and their phylogenetic diversities in deeply buried marine sediments of the Pacific Ocean Margins. During the Ocean Drilling Program Legs 201 and 204, we obtained sediment cores from the Peru and Cascadia Margins that varied with respect to the presence of dissolved methane and methane hydrate. To examine differences in prokaryotic distribution patterns in sediments with or without methane hydrates, we studied >2,800 clones possessing partial sequences (400 -500 bp) of the 16S rRNA gene and 348 representative clone sequences (Ϸ1 kbp) from the two geographically separated subseafloor environments. Archaea of the uncultivated Deep-Sea Archaeal Group were consistently the dominant phylotype in sediments associated with methane hydrate. Sediment cores lacking methane hydrates displayed few or no Deep-Sea Archaeal Group phylotypes. Bacterial communities in the methane hydrate-bearing sediments were dominated by members of the JS1 group, Planctomycetes, and Chloroflexi. Results from cluster and principal component analyses, which include previously reported data from the West and East Pacific Margins, suggest that, for these locations in the Pacific Ocean, prokaryotic communities from methane hydrate-bearing sediment cores are distinct from those in hydrate-free cores. The recognition of which microbial groups prevail under distinctive subseafloor environments is a significant step toward determining the role these communities play in Earth's essential biogeochemical processes.

Vertical distribution of archaeal communities in cold seep sediments from the jiulong methane reef area in the south China sea

“…MBG-B was also the dominant group in the hydrate-bearing sites of the Cascadia and Peru Margins; as well as in the sulfate reducing zone in shallow sediments above gas hydrates (INAGAKI et al 2006). It was suggested that MBG-B might play an important role in the biogeochemical processes of sulfate reduction and methane oxidation (BIDDLE et al 2006).…”

“…It was suggested that MBG-B might play an important role in the biogeochemical processes of sulfate reduction and methane oxidation (BIDDLE et al 2006). Although there is limited knowledge about the metabolic functions of the MBG-B group, the recognition of microbial populations that consistently occur in the presence of methane hydrates probably serves as a starting point for defining their ecological and biogeochemical significance (INAGAKI et al 2006). Our data also showed that MCG and SAGMEG were also dominant groups, with both of them increasing in abundance with depth.…”

Community Structure, Diversity, and Vertical Distribution of Archaea Revealed by 16S rRNA Gene Analysis in the Deep Sea Sediment of the Ulleung Basin, East Sea

“…E-mail : hyunjh@hanyang.ac.kr 행되어왔다 (Gray and Herwig 1996;Ravenschlag et al 1999). 그러나 최근 분자생태기술의 발달을 통하여 제한된 환경에서만 서식한다고 알려져 있던 고세균이 일반 해양 환경 및 심해 퇴적물 (Vetriani et al 1999;Reed et al 2002;Inagaki et al 2003;Newberry et al 2004;Biddle et al 2006;Inagaki et al 2006), 남극 퇴적물 (Bowman and McCuaig 2003;Kendall et al 2007), 냉용수(cold seep)지역 (Knittel et al 2005;Arakawa et al 2006), 메탄 누출(methane seep)지역 (Lloyd et al 2006;Dang et al 2009), 해저 열수구(hydrothermal vent)지역 (Takai and Horikoshi 1999;Reysenbach et al 2000;Teske et al 2002), 빈영양(organic-poor)해역 (Sørensen et al 2004), 갯 벌(tidal flat) (Wilms et al 2006) 및 염습지(salt marsh) (Nelson et al 2009)와 같은 다양한 해양환경에서 광범위 하게 분포하고 있음이 밝혀졌으며, 이를 바탕으로, 고세균 도 진정세균과 마찬가지로 해양 퇴적물에서 생지화학적 물질순환에 중요한 역할을 담당하는 것으로 인식되고 있 다 (Knittel et al 2005;Biddle et al 2006;Hallam et al 2006;Nicol and Schleper 2006).…”

“…외국의 경우 다양한 해양 환경에서 미생물에 의한 물질 순환에 대한 연구와 함께 16S rRNA 유전자 분석을 통하 여 해양 저층 퇴적물에서 고세균 군집 다양성에 관한 연 구가 활발하게 진행되고 있다 (Vetriani et al 1999;Reed et al 2002;Inagaki et al 2003;Newberry et al 2004;Biddle et al 2006;Inagaki et al 2006). 이에 비해, 국내 에서는 주로 연안이나 갯벌에서 진정세균의 다양성에 대 한 연구가 다수 진행되었으나, 고세균에 대한 연구는 갯벌 과 동해 연안의 수심 500-650 m 정도의 퇴적물에서 암모 니아 산화와 관련한 연구에 불과한 실정이다 (이 등 2001;조 등 2004;Kim et al 2005;Park et al 2008).…”

“…Euryarchaeota에 속하는 MBG D는 정점 M1의 표층(0-1 cm)에서는 나타나지 않았고, 깊이 8-9 cm에서 31.8%, 깊이 18-19 cm에서 20.3%의 비율로 나타났다( Table 1) (Reed et al 2002;Inagaki et al 2003;Biddle et al 2006;Inagaki et al 2006;Sørensen and Teske 2006). 본 연구에서 나타난 MBG B/DSAG 그 룹에 속하는 클론들은 주로 오흐츠크 해의 냉용수 지역과 Eel River Basin의 메탄 누출지 등 저층의 혐기성 조건에 서 나타난 클론들과 연관되어 나타나는 것으로 조사되었 다 (Fig.…”