Studies Of Cultivated Microorganisms Diversity And Funtion In The Antarctic Ross Sea Sediments And Taxonomic Analysis Of A Novel Bacteria From The Antarctic

There are few human activities in Antarctica.The sediments in the deep sea of Antarctica are not only complicated in geological characteristics,but also have a large number of mineral elements.Ross Sea is a deep bay in the South Pacific adjacent to Antarctic continent,located in the north of Ross ice shelf,between Victoria Adair Angle and Edward VII cole baker Angle?158°W-170°E?.In this study,the cultivated microorganisms diversities,as well as low-temperature activities have been tested in the Antarctic Ross Sea sediments.A novel genus of bacteria has been gained based on the analysis of genetics,phenotype,physiological and biochemical indexes and chemical classification indexBacteria and fungi were isolated from 6 sediment samples collected from Ross Sea via the traditional plate culture method.The bacteria and fungi with different morphology were selected for 16S rDNA and ITS identification.The results of 16S rDNA sequence,showed that there are presence of several bacteria in the samples such as Salegentibacter?7?,Bacillaceae?7?,Marinobacter?4?,Planococcus?6?,Psychrobacter?12?.The results of ITS identification showed that the fungi are classified into 6 genera:Cladosporium,Alternaria?Curvularia?Lecanicillium?Fimetariella?Penicillium.Among them,Cladosporium is the dominant fungi.Meanwhile we found 88.89%of the bacteria produce a-glucosidase,72.22%of the bacteria produce protease,83.33%of the bacteria produce urease,69.44%of the bacteria produce P-galactosidase,and 69.44%of the bacteria can transform the nitrate to nitrite and nitrogen.The fungi that produced amylase,cellulase and caseinase share the rate of total fungi 37.93%,34.48%and 61.54%.8 strains are antagonistic to at least one tested strain.Their antagonistic activity is mainly directed against fungi?Peronosporales capsici?and Gram-negative bacteria?Escherichia coli,Vibrio anguillarum?.There is no bacteria with the significant inhibitory effect on the strain?Bacillus subtilis?.The results showed that the microorganisms in the sediments of Ross Sea are rich in diversity,which can also provide the basis for the screening of the strains with special functions and the discovery of new strains.A strain of Antarctic bacteria 2PM7 was identified by traditional plate culture method with saline R2A medium.The results showed that the bacteria was Gram-negative bacteria,strictly aerobic,rod-shaped,no flagellum and no movement.the better growth condition at 0-20?,the better growth of the strain pH 4.0-8.0,the suitable medium is less than 0.9%?w/v?NaCl.The strain has the activity of oxidase and catalase.The content of G+C is 44.4 mol%;the cell respiration quinone is methyl naphthoquinone 7?MK-7?;the main fatty acids are iso-C₁5:0?18.1%?,Ci16:1?5c?14.2%?and Summed feature 3?40.5%?.The similarity between 2PM7 and Mucilaginibacter rugui sp.nov.is 96.8%and less than 96.8%compared with other bacteria is.The constructed phylogenetic tree shows that 2PM7 forms an independent branch.Therefore,strain 2PM7 is considered to representative a novel species belonging to Mucilaginibacter,named Mucilaginibacter ping sp.by us.