Change Of The Yangtze River Delta Region Of Soil Microbial Community Structure Of Different Developmental Stages

Chongming dongtan is located in Yangtze Rive, the largest wetland in China, a typical subtropical zone. Chongming Island had been reclaimed by silt year after year. At last, the island has formed a transparent soil which has"age". Therefore, it is give a good condition on researching different development stage of soil. Taicang is located opposite to Chongming Island, closed to Yangtze River estuary and belonged to alluvial plain too. Because of the people fertilized and farmed illegitimately, the soil was selected to be over-utilized sample. Two stage of soil development and soil over used were binded to evaluate microbial community. Microbial community structure played a important role in microbial ecology, the application of molecular methods increased the step of soil experiment effectively.This study selected wetland(0 year), paddyland and upland samples which both have soil age of 7,16,40,75,120,300 and 500year.454 pyrosequencing method was used to analyse the fungal population, the result showed the main phylum was Ascomycota, Chytridiomycota and Basidiomycota. Ascomycota had the largest population in fungal. The fungal diversity in paddyland and upland was higher than wetland. The Ascomycota contains Sordariomycetes, and the phylum of Basidiomycota mainly had class of Agaricomycetes.Real-time quantification PCR method was used to calculate the content of bacterial, fungal, ammonia oxidizing bacteria and mycorrhiza by utilizing the molecular markers of bacterial 16S rDNA, fungi ITS gene, bacterial amoA gene, nifH gene, and mycorrhiza 18S rDNA gene. The result showed that copy numbers in paddyland was higher than wetland, but in 7 years had a very low copies,120 year was 10 times than 7 year, and then droped in 300 year. The dryland copy numbers was between 9.0×105 to 1.11 X 106 copies/g dry soil. The lowest copies in fungal of wetland, paddyland had a highest copies in 7 year samples, the dryland had a descend curve along with ages upgrade. Ammonia oxidizing bacteria had small copies in wetland, while increased with the ages; samples from dryland was 10 times than wetland after 7 year. nifH gene's copy numbers went up with fertilized ages in paddyland and had no relationship with ages in dryland. The copies of wetland about mycorrihiza were large, the paddyland degraded in small ages but increased in 120 year. Four samples from Taicang was selected to do research. Taicang1(2year), Taicang2(5year). Taicang3(lyear) and Taicang4(reclaimed by house soil) samples constructed clone libraries to analyse the diversity of Bacterial, Fungal and Archaeal. From the tree we acquired Taicang2 and Taicang3 had a higher diversity than Taicangl and Taicang4 in bacterial. The main phylum was Proteobacteria, Firmicutes, Acidobacteria and so on. There was no difference between Taicang2 and Taicang3 sample in archaeal, mainly in Euryarchaeota and Crenarchaeota. Whereas, a big variable in fungal diversity. Taicang2 sample had a higher abundant than Taicang3 sample, the diversity of Taicang3 sample was mainly in Panaeolus retirugis and Taicang2 sample was collected in Uncultured ascomycete. The same steps and method of real-time quantification PCR were utilized to calculate the content of Taicang4 sample. The result showed the nifH gene and amoA gene copy number was very high.