The Soil Reinforcement Capability And High-throughput Sequencing Analysis Of Decabromodiphenyl Ether-degrading Bacteria Of The Rhizosphere Of Macrophytes

The wetland ecosystem is one of the three major ecosystems in the world and plays an important role in biodiversity conservation and pollution purification.Numerous studies have shown that aquatic plants in wetlands play a key role in maintaining the ecological function of wetlands.However,there have been no studies on the function of soil fixation in wetlands with fluctuating hydrological conditions such as estuarine wetlands,river bank wetland,Hydro-fluctuation belt wetlands.The mechanisms of wetland plants' Rhizosphere microorganisms in the degradation of pollutants also have few reports.In this paper,several common wetland aquatic plants were selected,and the relationship between their soil reinforcement capabilities and root characteristics was studied and compared.The purpose is to provide a reference for the restoration,management and maintenance of wetlands with severe hydrological conditions.In addition,on the basis of previous studies,high-throughput sequencing methods were used to analyze Decabromodiphenyl ether-degrading bacteria of the rhizosphere of Scirpus validus Vahl.The purpose is to explore the BDE-209 degrading bacteria and provide the basis for further experimental verification.In this experiment,the common aquatic plants Phragmites communis Trin.,Arundo donax L.and Cyperus alternifolius L.were studied.The anchor bar tension meter and self-made shear box were performed in situ shear tests to evaluate the shear resistance of different plants.At the same time,impact tests for these three species to calculate the anti-erosion coefficient of the plant rhizosphere soil and their anti-erosion ability.Comparing the shear resistance capability on the unit number of branches of different plants and the soil erosion resistance coefficient of different plants to evaluate the differences and their key constrained factors of the soil reinforcement capability in kinds of wetland plants.The main results are as follows:(1)The tests in situ shear showed that the shear strength on the unit number of branches of different plant species was Arundo donax L.>Phragmites communis Trin.=Cyperus alternifolius L.The reason may be that the root' dry mass on the unit number of Arundo donax L.is the largest,and the total number of unit branches is the maximum.Therefore,the larger total contact area with the soil shows a stronger ability to reinforce the soil.(2)The impact coefficient on unit number of branches of different plants in impact test showed that the rank was Arundo donax L.>Phragmites communis Trin.=Cyperus alternifolius L..The reason is that Arundo donax L.also has the largest average diameter of the stem,except for the largest root weight and the highest number of roots per unit.Therefore,the largest coverage per unit area of Arundo donax L.weakens the impact of surface runoff and reducing soil erosion caused by surface runoff.From the results of this study,it can be inferred that the total root number,root dry weight,and average stem diameter of the wetland plants are the key determining factors for the plant's ability to fix soil.These parameters can be used as the basis for the screening of plants in wetlands.These parameters can be used as choice basis for ability to reinforce the soil of different plants in wetlands.In the previous research of this laboratory,it was proved that the of aquatic plants Scirpus validus Vahl.has significant degradation ability to the POP-BDE-209,in which the rhizosphere bacteria play a major role in degradation.Therefore,in this study,high-throughput sequencing analysis was used to analyze the changes of microbial communities under different treatments,and the possible degrading genus was assumed.The following four treatment groups were set up:(1)SVL:Scirpus validus Vahl.+sediment + BDE-209(2mg/kg);(2)SVH:Scirpus validus Vahl.+ sediment + BDE-209(30mg/kg);(3)SVN:Scirpus validus Vahl.+ sediment(no adding BDE-209);(4)NL:sediment + BDE-209(2mg/kg).The main findings are as follows:(1)Through high-throughput sequencing analysis,it was found that in the bacterial community composition,the bacterial community was similar between the SVN group and the SVL group.However,the bacterial community compositions in the SVH group and NL,SVL,and SVN groups were quite different.(2)Proteobacteria is the absolutely dominant of bacteria in the rhizosphere soil bacteria between non-plants added with 2mg/kg of pollutants and under the treatment of three different pollutant concentrations.Deltaproteobacteria is also absolutely dominant in each group.(3)Analysis of LEfSe(LDA Effect Size)revealed that the differential species Biomarker in the SVH group was Desulfobulbaceae and Desulfobacterales.(4)According to the screening comparison,the bacterial species with a significant increase in relative abundance after BDE-209 treatment were found,such as Desulfobulbus,Ideonella,unidentified_Nitrosomonadaceae,Byssovorax,Novosphingobium,Sulfuritalea,Woodsholea,Desulfatirhabdium,Sterolibacterium,Roseomonas,unidentified_Rhodospirillaceae,Aeromonas,Polymorphobacter,Desulfomonile,Vogesella may be BDE-209 degradation bacteria of Scirpus validus Vahl.However,the exact BDE-209 degrading bacteria in the rhizosphere of Scirpus validus Vahl.are still need further verification.