Research On Methanol-oxidizing Bacteria Communities From Different Habitat Based On XoxF Genes Sequences

Methanol is an intermediate in the methane oxidation process.And the high concentration of methanol may inhibit methane oxidation by feedback inhibition of methane monooxygenase.Based on mxaF and xoxF amino acid sequences phylogenetic analysis showed that the methanol dehydrogenase protein family made up by six distinct clades(mxaF and xoxF1-5)at least.And the xoxF gene,a methanol dehydrogenase in methylotrophic bacteria was recently discovered.Using xoxF gene in the marine environment to detect lot of methanol oxidizing bacteria,however little is known about its diversity in wetland sediments and grassland soil.In order to examine the diversity of methanol-oxidizing bacteria in wetland sediments and grassland soil,we selected typical wetland and grassland in Inner Mongolia plateau as study area.The surface soil or sediment samples were obtained from three wetlands(eutrophicated-Wuliangsuhai wetlands and Xilin River wetland,Xilin River reservoir)and a typical grassland Maodeng ranch.Total DNA from each samples were extracted,then xoxF5 gene was amplified to contruction the clone library.221 clones(132 OTUs)were sequenced and analyzed for the methanol-oxidizing bacteria communities.The results were showed as follows:(1)In the three wetland sediments,methanol-oxidizing bacteria were classified into three common bacteria class including Alphaproteobacteria(12-48%),Betaproteobacteria(7-47%),Gammaproteobacteria(37-54%),but relative abundance of each bacteria class were different from each habitat.In genus lever,Type I methanotrophs(Cluster 6 and Cluster 8)of Alphaproteobacteria were detected as the common major group in Wuliangsuhai Wetland(WWT),Xilin River Reservoir(XRR)and Xilin River Wetland(XWT)(abundance 17%,38%and 22%,respectively).Secondly,the relative abundance of Hyphomicrobium related Cluster3B was much higher in Wuliangsuhai(WWT,22%)and Xilin River Reservoir(XRR,41%).And Methylibium sp.Rootl272 related OTU005 was specific dominant bacteria(abundance,16%)in Xilin River wetland.Beggiatoa related Cluster 4(16%)was also the main specificity flora of Wuliangsuhai wetland.These results showed that Methanotrophs were also major methanol-oxidizing bacteria in wetlands and may provide carbon nutrition for other methanol-oxidizing bacteria related nitrogen or sulfur cycle.(2)Methanol-oxidizing bacteria were classified into Alphaproteobacteria(abundance,63%),Betaproteobacteria(13%),Gammaproteobacteria(5%),Firmicutes(17%)and Actinomycetes(2%)in Maodeng grassland soil.Among them,Hyphomicrobium-related Cluster 3B(16%)and Bradyrhizobium-related Cluster 3A(23%)of Alphaproteobacteria,and the unknown Firmicutes(Cluster 5,20%)were the main methanol-oxidizing bacteria groups,and Type ? methanotrophs(4%)of Gammaproteobacteria.Compared with wetlands,Bradyrhizobium and unknown Cluster 5 were grassland specific bacteria groups.Methanol oxidizing bacteria may played an important role in soil nitrogen cycling in grassland soils.(3)The results of the diversity analysis of methanol oxidizing bacteria:The highest index of Shannon(H '= 3.62)in the Maodeng grassland,Xilin River Wetland(3.32),Xilin River Reservoir(3.18)and Wuliangsuhai Wetland(2.88).The results of RDA analysis showed that the concentration of phosphorus,ammonia and pH value could have a certain influence on the methanol-oxidizing bacteria communities.