Sulfate-reducing bacteria(SRB),which obtain energy from dissimilatory sulfate reduction,play a vital role in the carbon and sulfur cycles.The dissimilatory sulfite reductase(Dsr),catalyzing the last step in the sulfat...Sulfate-reducing bacteria(SRB),which obtain energy from dissimilatory sulfate reduction,play a vital role in the carbon and sulfur cycles.The dissimilatory sulfite reductase(Dsr),catalyzing the last step in the sulfate reduction pathway,has been found in all known SRB that have been tested so far.In this study,the diversity of SRB was investigated in the surface sediments from the adjacent area of Changjiang Estuary by PCR amplification,cloning and sequencing of the dissimilatory sulfite reductase beta subunit gene(dsr B).Based on dsr B clone libraries constructed in this study,diversified SRB were found,represented by 173 unique OTUs.Certain cloned sequences were associated with Desulfobacteraceae,Desulfobulbaceae,and a large fraction(60%) of novel sequences that have deeply branched groups in the dsr B tree,indicating that novel SRB inhabit the surface sediments.In addition,correlations of the SRB assemblages with environmental factors were analyzed by the linear model-based redundancy analysis(RDA).The result revealed that temperature,salinity and the content of TOC were most closely correlated with the SRB communities.More information on SRB community was obtained by applying the utility of Uni Frac to published dsr B gene sequences from this study and other 9 different kinds of marine environments.The results demonstrated that there were highly similar SRB genotypes in the marine and estuarine sediments,and that geographic positions and environmental factors influenced the SRB community distribution.展开更多
China＇s oil demand has been skyrocketed. In 2004 China became the world＇s second largest oil consumer and imported 122.7 million tons of crude oil, which accounted for 41.9% of China＇s crude oil consumption. Intern...China＇s oil demand has been skyrocketed. In 2004 China became the world＇s second largest oil consumer and imported 122.7 million tons of crude oil, which accounted for 41.9% of China＇s crude oil consumption. International oil investment becomes an important channel for China to obtain oil resource. The cluster analysis in the target countries of China＇s international oil investment is studied here. An investment environment model incorporating 9 factors is established firstly, the order of these factors is ranked by their importance. Then the weight of such factors is determined by Analytic Hierarchy Process （AHP） and these countries are classified into 3 categories using cluster analysis. The results provide an important decision-making tool for China＇s international oil investment.展开更多
基金supported by the National Natural Science Foundation of China and the National Basic Research Program of China (973 program)(Nos.40920164004,2011CB403602,41375143)
文摘Sulfate-reducing bacteria(SRB),which obtain energy from dissimilatory sulfate reduction,play a vital role in the carbon and sulfur cycles.The dissimilatory sulfite reductase(Dsr),catalyzing the last step in the sulfate reduction pathway,has been found in all known SRB that have been tested so far.In this study,the diversity of SRB was investigated in the surface sediments from the adjacent area of Changjiang Estuary by PCR amplification,cloning and sequencing of the dissimilatory sulfite reductase beta subunit gene(dsr B).Based on dsr B clone libraries constructed in this study,diversified SRB were found,represented by 173 unique OTUs.Certain cloned sequences were associated with Desulfobacteraceae,Desulfobulbaceae,and a large fraction(60%) of novel sequences that have deeply branched groups in the dsr B tree,indicating that novel SRB inhabit the surface sediments.In addition,correlations of the SRB assemblages with environmental factors were analyzed by the linear model-based redundancy analysis(RDA).The result revealed that temperature,salinity and the content of TOC were most closely correlated with the SRB communities.More information on SRB community was obtained by applying the utility of Uni Frac to published dsr B gene sequences from this study and other 9 different kinds of marine environments.The results demonstrated that there were highly similar SRB genotypes in the marine and estuarine sediments,and that geographic positions and environmental factors influenced the SRB community distribution.
文摘China＇s oil demand has been skyrocketed. In 2004 China became the world＇s second largest oil consumer and imported 122.7 million tons of crude oil, which accounted for 41.9% of China＇s crude oil consumption. International oil investment becomes an important channel for China to obtain oil resource. The cluster analysis in the target countries of China＇s international oil investment is studied here. An investment environment model incorporating 9 factors is established firstly, the order of these factors is ranked by their importance. Then the weight of such factors is determined by Analytic Hierarchy Process （AHP） and these countries are classified into 3 categories using cluster analysis. The results provide an important decision-making tool for China＇s international oil investment.
