Distribution,Diversity And Metabolism Of Bathyarchaeota And Methane Metabolizing Microbes In Northern Slope Of Sh China Sea

Marine sediments preserved the high amount of microbes,which play an important role in organic matter degradation and nutrient cycles.The Sh China Sea(SCS)was a classical marginal sea in the west part of the Pacific Ocean and located in the passive continental margin.Based on the geological survey and drilling detection,large amount of gas hydrate were found in the northern slope of SCS.More than 30 seeps have been investigated in SCS and two of them are active cold seeps,called Formosa cold seep and Haima cold seep,which were newly found in 2015.The microbial distribution,diversity and ecological function in the cold seeps and methane hydrate regions of the Sh China Sea(SCS)are poorly constrained.So our study will research on the microbial distribution,diversity and their ecological function in Haima cold seeps and methane hydrate region of Dongsha and Shenhu area in northern slope of SCS.This study is very helpful for understanding microbial diversity,distribution and ecological roles for some of the specific microbial groups in cold seeps and methane hydrate regions of SCS.Our scientific questions of research are following:(1)determine the microbial communities involved in methane metabolization in the SCS,particularly,if there are specific methane-metabolizing archaeal groups in the SCS? Further illustrate the environmental factors controlling the niche separation and distribution of methane-metabolizing archaea,especially ANME subgroups and investigate the interactions between methanemetabolizing microbes and the other archaea in the communities.(2)Comparing the different distribution pattern mainly focus on the subgroups of Bathyarchaeota in with and with methane hydrate sediment.Whether the specific subgroups of Bathyarchaeota exist in methane hydrate sediments.Identified the interaction between environmental factors and archaeal groups/subgroups of Bathyarchaeota.(3)Investigate the microbial metabolism in different environment sediment in methane hydrate region and mainly focus on the relationship between microbial metabolism and diversity.Here,we reported the archaeal communities,particularly those involved in methane metabolization,in the sediments of a newly discovered cold seep.Archaeal diversity,abundances,and distribution were investigated in two piston cores collected from the seep area of ROV1(QDN-14B)and a non-seep control site(QDN-31B).The geochemical analysis identified a sulfate-methane transition zone(SMTZ)at 300-400 cm in QDN-14 B,where a high abundance of anaerobic methane oxidizers(ANMEs)occurred revealed by analyzing the 16 S rRNA gene and the key gene of the alpha subunit of methyl coenzyme M reductase(mcrA).ANME-2a/b was predominant in the upper and middle layers of the SMTZ,while ANME-1b competed ANME-2 in the sulfate-depleted bottom layers of the SMTZ and the methanogenic zone.The fine phylogenetic analysis further divided the ANME-1b group into three subgroups with different distribution patterns: ANME-1b Ⅰ,ANME-1b Ⅱ,and ANME-1b Ⅲ.Multivariate analyses indicated that dissolved inorganic carbon and sulfate could be important controlling factors for the composition of the methanemetabolizing community.Based on the geological and seismological survey,a huge amount of methane hydrate preserved in Donghsha and Shenhai area.This research detected archaeal diversity in methane hydrate regions of Shenhu and Dongsha area.The main archaeal groups in all samples from the sediments with or with methane hydrate were Bathyarchaeota,Parvarchaea,Thaumarchaeota and Thermoplasmata.According to the Analysis of Similarity(ANOSIM),the archaeal diversity was significant a difference between with and with methane hydrate sediment.Through the Similarity Percentage analysis(SIMPER),Bathyarchaeota and Thermoplasmata contributed the most on the segregation of samples according to habitat.Some specific subgroups of Bathyarchaeota only distributed in sediment with methane hydrate.Multivariate analyses identified sulfate,DIC,TOC and depth as predictor variables of archaeal and subgroups of Bathyarchaeota community composition.The geochemical factors have large divergence between two samples(CH03-10 and CH03-750)from different depth.The samples are appropriate environments for studying the links between composition and functionality in microbial communities.We explored these aspects through metagenomics and in silico reconstruction of carbon,nitrogen and sulfur metabolic pathways that were tightly coupled through a few bacterial and archaeal groups.The potential for anaerobic carbon fixation(WL pathway)was detected and dominant in both surficial and bottom layer,with a major role for CO oxidation and anaerobic carbon fixations in Dehalococcoidia.Nitrate/nitrite reduction process was main metabolism in CH03-10,involved by Candidatus Brocadiales.While,nirtrogen fixaton that Desulfovibrio vulgaris involved in was main metabolism in CH03-750.Desulfobulbaceae accounted for a large percentage of dissimilatory sulfate reduction genes in CH03-10.Chloroflexales were putatively involved in assimilatory sulfate reduction in CH03-750.We also detected the genes involved in aromatic organic matters.BamB-I and BbsA-H genes were dominant in both samples and further indicated that microbial communities in both samples potentially mediated the degradation of aromatic organic matters.Our study on ANME niche separation and interactions with other archaeal groups improved our understanding of the metabolic diversity and flexibility of ANMEs and further suggested that ANME subgroups may have evolved diversified/specified metabolic capabilities than syntrophic anaerobic oxidation of methane coupled with sulfate reduction in marine sediments.Bathyarchaeota and Thermoplasmata contributed the most on the segregation of samples according to habitat(with vs.with methane hydrate).The specific subgroups of Bathyarchaeota in sediment with methane hydrate were potentially proxies for methane hydrate detection.In this studies,the archaeal diversity and distribution pattern in Haima cold seep and the sediment with and with methane hydrate were investigated by 16 S rRNA gene based high-throughput methods and multivariate analysis.Identifying various functional genes in metagenome of different samples revealed the ecological roles of some microbial groups in different sediments.Our works made the first investigation in microbial,especially for methane metabolizing microbes,diversity and distribution in the cold seep and made systemically detection for archaeal composition and distribution in the sediment with and with methane hydrate regions in SCS.That paved the way for further research ab microbial diversity,distribution,evolution and ecological roles in cold seeps and methane hydrate regions of SCS.