Effects Of Spartina Alterniflora Invasion On Bacterial Community Related To Carbon-sulfur Cycle In Chongming Dongtan

Wetland is a multifunctional ecosystem which is rich in biodiversity. It is a model environment for research on the relationship between different microorganisms and plants structure and function. In the wetland environment, sulfur changes with the change of environmental conditions under microbial oxidation or reduction, which construct the biogeochemical cycle of sulfur. Biogeochemical cycle of sulfur is closely related to carbon cycle process. Both methane-producing process and sulfate-reducing process belong to an important terminal process of organic carbon mineralization in anaerobic environment. Sulfate reducing process can produce H2 S, which can provide substrate for autotrophic sulfur oxidizing bacteria(SOB) and at the same time coupling with carbon fixation to synthesis biomass make use of CO2 in the air. The sulfur cycle related bacteria has abundant metabolic diversity. In recent years, sulfur cycle related bacteria and the interaction between it and the carbon conversion process has gained more attention.In this study, combined with constructing the clone library, Real-time PCR,denaturing gradient gel electrophoresis(DGGE) and sequencing, we researchon the effect of Spartina alterniflora invision on biogeochemical sulfur cycle and the related carbon conversion process as well as the bacteria community structure and diversity in Chongming Dongtan Wetland. The main contents and results of the study are as follows:1) The wetland soil samples with different Spartina alterniflora invasion succession were collected to detected the carbon-fixing SOB community structure.SOB mainly attributable to Chlorobia, Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria. Carbon-fixing-SOB mainly attributable to Alphaproteobacteria and Gammaproteobacteria, which is consistent with SOB community classification. Chlorobia is the dominant bacteria of SOB, which covers 30.0%-79.0% of the clones. Chromatiales is the dominant bacteria of Carbon-fixing-SOB,which covers 80.4%-95.5% of the clones.As the S. alterniflora invision time increases,the abundance of sox B gene first increases then decreases, the A3 sample has the greatest abundance(1.93×1010 copies/g) and the A1 sample has the lowest abundance(4.22×109 copies/g). The abundance of cbb L gene changes between3.06×109 copies/g and 3.77×109 copies/g.2) As the S. alterniflora invision time changes, the community structure of sulfate-reducing bacteria(SRB) and methanogenic bacteria changes. Methanogenic bacteria mainly attribute to Methanomicrobia, Methanothermea and Methanobacteria,and Methanomicrobia is the dominant bacteria. SRB mainly attributable to Deltaproteobacteria and Clostridia. Desulfobacterales is the dominant bacteria of SRB, which covers 52.9%-65.5% of the clones.The abundance of dsr B gene is two orders of magnitude higer than mcr A.The abundance of mcr A(1.20×107 copies/g soil-4.75×107 copies/g soil) first increases then decreases as invision time increases. The abundance of dsr gene(2.61×109-3.23×109 copies/g soil) of A1-A3 samples have no significant difference and they are all higher than A4 sample(1.83×109 copies/g soil).3)The effect of S. alterniflora invision on SRB, SOB and methanogenic bacteria in native Phragmites australis-growing soil were studied through Phragmites australis-spartina alterniflora paired samples. SRB Includes Deltaproteobacteria and Clostridia. Desulfobacterales is the dominant bacteria of SRB, which covers69.23%-72.31% of the clones.SOB mainly attribute to Alphaproteobacteria,Betaproteobacteria and Gammaproteobacteria. Gammaproteo- bacteria(27.43%-40%) and Betaproteobacteria(29.66%-32%)are dominant bacteria of SOB.mcr A includes Methanomicrobia, Methanothermea and Methanobacteria, among which Methanomicrobiales of Methanomicrobia is the dominant bacteria. The abundance of dsr B, sox B and mcr A gene of spartina alterniflora(dsr B: 3.60×109copies/g soil; sox B: 1.16×1010 copies/g; mcr A: 8.08×105 copies/g soil) are significantly higher than that of Phragmites australis(dsr B: 1.81×109 copies/g soil;sox B: 1.09×1010 copies/g; mcr A: 6.18×105 copies/g soil), which indicates that the invision of spartina alterniflora promotes the growth of SOB, SRB and methanogenic bacteria.4)The effect of spartina alterniflora invision on SRB, SOB and methanogenic bacteria in native Scirpus mariqueter-growing soil were studied through Scirpus mariqueter-spartina alterniflora paired samples. SRB all belongs to Deltaproteobacteria, including Syntrophobacterales, Desulfobacterales and Desulfarculales.Desulfobacterales is the dominant bacteria of SRB, which covers 52.21%-60.63%of the clones. SOB includes Chlorobia, Alphaproteobacteria, Betaproteobacteria and Gammaproteobacteria, among which Chlorobiais the dominant bacteria(47.27%-52.97%). Methanogenic bacteria includes Methanomicrobia,Methanobacteria and Methanococcior and Methanomicrobia is the dominant bacteria.The abundance of dsr B, sox B and mcr A gene of spartina alterniflora(dsr B:1.68×109copies/g; sox B:6.66×109 copies/g; mcr A:8.80×105 copies/g) are significantly higher than that of Scirpus mariqueter(dsr B:1.34×109 copies/g; sox B:6.16×109 copies/g;mcr A:2.66×105 copies/g), which indicates that the invision of spartina alterniflora promotes the growth of SOB, SRB and methanogenic bacteria.In conclusion, Spartina alterniflora invision can change physicochemical properties such as soil carbon and nitrogen pools through root secretion and litter.Consequently, microorganism community structure and diversity changes greatly and sulfur-/carbon-cycling related microorganism has cooperative response with Spartina alterniflora invision.The results of this study is to provide scientific basis for the invasion of Spartina alterniflora on microbial ecological environment influence mechanism and the mechanism of microbial function.