Molecular Ecology Study Of Microorganisms In The Pacific Ocean "Warm Pool" Deep Sea Sediments

The west Pacific Ocean "Warm Pool" plays an important role in global climate change, which makes it become one of the most important focuses of geoscience research. In this study, we investigate the microbial diversity of deep sea sediments and analyze the characteristic of substance and energy conversion driven by microorganism in "Warm Pool" area for the first time.Samples including deep sea sediments of the Pacific Ocean and other environmental samples from polar region were collected and analyzed. The profile of microbial community structures in different deep sea sediments was evaluated and the interaction between microorganisms and environment was analyzed by culture-independent molecular phylogenetic methods. Psychrophilic and psychro-tolerant bacteria were cultured and used for screening the cold-active enzymes. Some characteristics of cold-active protease and chitinase were analyzed then.Microbial 16S rDNA (ribosomal DNA) clone libraries of deep sea sediments were constructed and studied by PCR-RFLP (Restriction Fragment Length Polymorphism) and phylogenetic analysis based on 16S rDNA sequences. The microbial diversity and community structures of deep sea sediments collected from two different sea area including the west Pacific "Warm Pool" and the east Pacific "Manganese nodule" area, as well as the interaction between microbial community and environment, were analyzed based on these studies. Members of the γ-proteobctcteria and α-proteobacteria were found to be most abundant in both areas, and members of β-proteobacteria were seldom detected. The difference of microbial group between different sea areas was the 8- and e- subdivision of proteobacteria, which was abundant at upper sediment of "Warm Pool" area while they were not detected at the sediments of "Manganese nodule" area. At the core sediment of "Warm Pool" area, members of δ-proteobacteria reduced from upper to lower sediments. Members of the CFB (Cytophaga-Flexibacter-Bacteroides) were found to be rich in upper sediment of "Warm Pool" while they were not detected in sediment from "Manganese nodule" area, which indicated that there were more organic substances in the "Warm Pool" area. The results of archaeal diversity analysis showed that most of the members belonged to Crenarchaeota, and included many unidentified archaea species.Abundant bacteria related to the metabolism of sulfur and methane were found in sediment collected from "Warm Pool" area, which indicated that the metabolism of sulfur and methane played an important role in the substance and energy conversion of this area. The distribution and amount analysis of these bacteria in different layers of core sediment indicated that there was an intact cycle that coupled sulfur metabolism with methane metabolism existed in this area, which may be the microbial response to the environment because there was seldom similar bacteria detected from "Manganese nodule" area sediment by DNA-DNA hybridization with specific oligonucleotide probe and 16S rDNA clone library analysis. It could play an important role in the evolution of "Warm Pool" area.More than 300 pure psychrophilic and psychro-tolerant bacteria were isolated from environmental samples. The analysis of growth indicated that all strains could grow well at 4℃~15℃ while they could grow poorly at 25℃~30℃, and few of them could grow constrainedly at 37℃. More psychrophiles isolated from antarctic samples than that from deep sea sediments. The molecular classification and identification of psychrophiles based on 16S rDNA sequences indicated that Pseudoalteromonas sp. and Pseudomonas sp. were common in strains isolated.The unique 16S rDNA fragment of marine psychrophiles was studied based on the comparison of 16S rDNA sequences. The results indicated that the PCR primers designed could distinguish between marine bacteria and terrestrial bacteria, and could be applied in distinguishing the psychrophiles.Sixteen strains which could produce cold-active protease and chitinase were screened by selective medium and...