Microbial Community Diversity Of The Deep Sea Cold Seep And Seamount-extreme Environments In Tropical Western Pacific

Deep sea is an important component of marine ecosystem.It has a complex and diverse environment such as seamounts and cold seeps and hydrothermal.Deep sea also has special physical and chemical characteristics such as high salt,high pressure and low temperature.These characteristics of deep sea gave birth to a unique microbial community structure.Studies of microbial diversity in the extreme environment of the deep sea can expand knowledge of the extreme environment of the deep sea,and tap the extreme environment resources of the deep sea,explore the relationship between organisms and environment,and further analyze microorganisms in geochemical cycling.Therefore,studying the microbial community structure of the extreme environment of deep-sea is necessary.In order to resolve microbial diversity of the deep sea cold seep and seamount extreme environment,we isolated and phylogenetically analyzed epiphytic bacteria from mussels collected from the cold seep,and also resolved microbial diversity of Yap seamount.Methane and hydrogen sulfide are enriched in the cold seep.Cold seep forms a typical ecological system,where lives a lot of mussels.Deep-sea mussels contain abundant epiphytic bacteria in their gills.Epiphytic bacteria play an important role in the process of material absorption and metabolism of mussels.In this study,mussels were firstly cultured for 24 h,followed by culturing 240 h in the sea water supplemented with methane or added sodium sulfide.The changes of community structure of epiphytic bacteria were analyzed.A total of 270 strains were obtained,which belong to four phyla.The predominant group is Proteobacteria.We found that the diversity of epiphytic bacteria in fresh mussel-gills in situ was high,while the community diversity of epiphytic bacteria began to decrease 6 h later.In methane treatment group,the number of pseudomonas related to carbon metabolism increased gradually.In the group treated with sodium sulfide,Bacillus increased gradually.Besides,four strains,which showed no highly homologous sequence in GenBank,and might be new species were also isolated.In this study,mussels collected from the cold seep in South China Sea were successfully cultured in laboratory,and the epiphytic bacteria community structure of gills of mussels were analyzed.This research is quite significant to enrich marine extreme environmental microbial resources database and offers some clues to further analyze the interaction between the mussel and epiphytic bacteria.In addition,the microbial community structure of 34 sea water samples in Luzon Strait to Yap seamount section which were collected from the six depths in the nine stations was analyzed through high-through sequencing,and microbial diversity was also analyzed.Based on the V4 region of 16 S rRNA gene,sequence analysis showed that bacterial communities in the 34 seawater samples were dominated by Proteobacteria,followed by Cyanobacteria,Actinobacteria,Firmicutes and Bacteroidetes.Cluster analysis revealed that the surface samples were gathered together.Combined with non-metric multidimensional scaling analysis,it was found that in addition to the Y3-15 and DY11 stations,other stations were arranged according to the depth,and depth was the main factor influencing the microbial diversity.Y3-15 and DY11 stations of the same depth and other stations of low-depth got together.We speculated that Y3-15 station due to seismic activity lead to sudden rise in the water,while DY11 station due to subduction trenches made the overall water upward trend.Investigation of microbial community structure in a wide-range area of this region is a significant foundation to know the basic information of microbial distribution and lay the foundation for the study of relationships between the microorganisms and the environment.