Molecular Ecology Study On Marine Planctomycetes

In recent decades,Planctomycetes has become one of the focused groups,for Planctomycetes is a microbial model to explore the evolution relationship between bacteria and eukaryotes for its characteristic of compartment and peptidoglycan-less. Previous work showed that Planctomycetes played important roles in marine carbon and nitrogen cycles such as anammox processes attributed to 30-70%marine nitrogen gas losses.Although Planctomycetes investigations have been increased,little is known about the distribution,diversity and abundance of Planctomycetales regarding marine environments.Here we present some molecular works on marine Planctomycetes.1) 16S rRNA gene approach is applied to investigate Planctomycetes community in the vertical deep sea sediment of the South China Sea and the latitludinal surface seawater of the Western Pacific Ocean.For the vertical sediment of the South China Sea,PCR amplification using the primer set Pla-46-F/1392-R of the samples from seven sediment layers(0.1m,1m,3m,5m,7m,9m and 11m below the surface sediment) showed that Planctomycetales existed within a limited range of sediment depths(≤5m), and had a decreasing tread in diversity with increasing depth.The majority of the Pla-46-F/1392-R retrieved sequences belong to Pirellula-related Planctomycetales,For the latitludinal surface seawater of the Western Pacific Ocean,the results revealed that Pirellula-Rhodopirellula-Blastopirellula clade dominated the Planctomycetes community(between 83.3%and 94.1%) in all surface seawater sites and was present unexpected diverse while the minority of genera Gemmata and Planctomyces were only found in sites H5 and H2 respectively.Interestingly,diversity of low latitudes seawater appeared higher than of mid-lantitudes,∫-libshuff software analysis revealed significantly different diversity pattern between in the latitudinal surface seawater and in the sediment,possibly response to different hydrological and geographic features2) Two new reverse primers(Pla-1097-R and Pla-1368-R) are designed,which greatly promote the potential ability of the forward primer Pla-46-F,both theoretically and experimentally.The test showed that PCR using the new primer sets reduced mismatches to non-Planctomycetes and supplemented the diversity of Planctomycetes, especially increasing the numbers of genera of Planctomycetes in both seawater and sediment samples.Our results strongly suggest that the diversity of Planctomycetes as revealed by Pla-46-F/1392-R has been potentially underestimated.3) Molecular evidences of ammonium oxidizing microorganisms were present in the 0.1m layer in the South China Sea sediment station MD2896,including anammox-related 16S rRNA gene sequences,beta-Proteobacteria ammonium oxidizing bacteria 16S rRNA gene sequences and archaea amoA gene sequences.Our data suggested that there are comprehensive competitions or cooperations among different ammonium oxidizing microorganisms in the sediment.4) CARD-FISH approach was applied to investigate the abundance of Planctomycetes in China seas.Our data revealed that the abundance of Planctomycetes was varied 0.23-20.53×10~4 cells/ml in The Yangtze River estuary and 0.15-10.25×10~3 cells/ml in the seawater columns of the South China Sea respectively.Even though higher than in the seawater columns of South China Sea,the abundance of Planctomycetes in The Yangtze River estuary is lower than previous reported in soils and sediments.