Study On Denitrifying Bacteria Of The Soils In The Constructed Wetlands Under Different Vegetation Conditions Based On Illumina Sequencing

In this paper,through the construction of constructed wetlands,with Phragmites australis and Phalaris arundinacea as wetland plants,on the basis of the deter mination of nitrification-denitrification rate of different soils in the constructe d wetlands under different vegetation conditions,using Quantitative Real-time P CR,the gene abundance of denitrification function was measured,and further using Illumina's Miseq sequencing platform,the structure diversity of bacterial community of the soils in the constructed wetlands with Phragmites australis a nd Phalaris arundinacea was studied,especially the dominant bacteria associate d with nitrogen transformation.Based on the above studies,this paper analyzed the relationship among soil nitrification-denitrification rates,denitrification func tional gene abundances,and dominant nitrogen-removing bacteria in the constru cted wetlands under different vegetation conditions.The structure characteristics of bacterial community of the soil in the constructed wetlands were elucidated from the perspective of molecular ecology,laying a good foundation for the i dentification and development and utilization of denitrifying functional bacteria in the next step,at the same time for the construction of constructed wetland,nitrog en decontamination mechanism to provide theoretical support and technical guidanc e,the main conclusions are as follows:(1)The nitrification rate of the soil in the constructed wetland with Phala ris arundinacea was far higher than that with Phragmites australis,reaching a significant level(P<0.05).The denitrification rate of the soil in the constructed wetland with Phragmites australis was slightly higher than that with Phalaris arundinacea,but no significantly difference(P>0.05),and fertilization can promo te the nitrification-denitrification rate of constructed wetlands soil.(2)There was no significant difference in total bacterial abundance in diff erent constructed wetlands,but the bacterial community structure was different.Nitrification-determining ammonia-oxidizing bacteria and denitrifying bacteria wi th nir SC1,nir SC2,nir KC3,and nirKC4 genes are dominant of the soil in the constructed wetland with Phalaris arundinacea,and denitrifying bacteria with with nirKC1 and nirKC2 genes are dominant of the soil in the constructed we tland with Phragmites australis.(3)In the constructed wetlands under different vegetation conditions,the i ntroduction of plants increased the abundance of specific nitrogen-removing bac teria in the soil.The dominant bacteria in the soil of Phragmites australis con structed wetland belong to Trichococcus,Clostridium,Bacillus,Desulfocapsa,T hiobacillus,Anaeromyxobacter,Nitrospiraceae,Thermomonas,Azoarcus,Geobact er and Ramlibacter etc,and some of the bacteria are closely related to the ge nus nirK and nirS.The dominating bacteria in the soil of Phalaris arundinace a constructed wetland include Desulfocapsa,Thiobacillus,Anaeromyxobacter,Ni trosomonadaceae,Geobacter,Nitrospiraceae,Nitrosospira,Anaeromyxobacter,Ni trosomonas,and Azoarcus etc.Among them,some belong to the ammonia-oxidi zing bacteria(AOB),and some have a close genetic relationship with nirK and nirS.(4)The abundance of nitrogen removal gene AOA amo A(1.66×10~9copies/g),AOB amo B(5.36×10~6copies/g),nir SC1(9.14×10~6copies/g),nirSC2(5.36×10~3copies/g),nirKC3(5.82×10~8copies/g),and nir KC4(5.10×10~5copies/g)of the soil in Phalaris arundinacea constructed wetland was high,and nitrogenous domin ant bacteria such as Nitrosomonadaceae,Geobacter,Nitrospiraceae,Nitrosospira,Anaeromyxobacter,and Nitrosomonas are abundant,which provided a microbio logical basis for soil denitrification,so it had stronger denitrification and decon tamination potential than that in Phragmites australis constructed wetland.