Effect Of Strain And Louts Seed Pods Synergistic Strain On Arsenic Bioaccumulation Of Pteris Vittata

Arsenic,a carcinogenic metal,poses a serious risk to human health.Among the treatments of arsenic-contaminated soil,phytoremediation with low investment cost,simple management and environmental friendliness is a promising method for arsenic remediation.In this study,the effect of the bacterial agent having As(V)and Fe(III)-reducing abilities and louts seed pods synergistic bacterial agents on the changes of water-soluble plus exchangeable arsenic(WE-As)in soil was studied by soil experiment.Additionally,the effect of bacterial agent and louts seed pods synergistic bacterial agents on arsenic accumulation by Pteris vittata was studied by pot experiment.The main results were as follows:1.A kind of Enterobacter species(strain E1),which could produce siderophore and indole acetic acid(IAA)and simultaneously dissolved phosphate,was found to activate soil arsenic.Strain E1 exhibited arsenate [As(V)] and Fe(III)reducing abilities during cultivation and its resistance to As(III)was 8 mmol/L.The possible role of activation of arsenic by strain E1 was subsequently investigated by exposing As(V)-absorbed ferrihydrite to the bacterial culture.Speciation analyses of As showed that strain E1 significantly increased soluble of As and Fe and that more As(V)was reduced to arsenite.The soil simulation experiment found that after 50 days,strain E1 significantly increased the concentration of WE-As by 32.2% compared with the control.In the pot experiment,the biomass,arsenic content and chlorophyll content of P.vittata treated with strain E1 significantly increased by 30.03%,74.9% and 112.1%,respectively.Strikingly,in the potted soil,WE-As significantly increased by 52.05%,while Fe-bound arsenic(Fe-As),residual arsenic(Res-As)and total arsenic decreased by 29.64%,19.65% and 11.04%,respectively.These results indicated that strain E1 effectively increased As accumulation in P.vittata mainly by promoting plant growth and dissolving soil arsenic.Additionally,microbial diversity and increased soil enzymatic activities in soil indicated that strain E1 posed few ecological risks.2.This study discovered a As(V)-reducing bacterium,Acinetobacter sp.C13,which produced siderophores and IAA.The potential of this strain in conjunction with louts seed pods for remediation of arsenic-contaminated soil was investigated.The soil simulation experiment found that after 30 days,strain C13 and louts seed pods significantly increased WE-As by 27.71% and 30.65%,respectively,compared with the control.In the pot experiment,compared with the control,the lotus seed pod significantly increased the As content and extraction amount of P.vittata by 95.10%and 198.55% respectively;strain C13 significantly increased the biomass,As content and extraction amount of P.vittata by 68.23%,77.45% and 106.39%,respectively.The synergies of strain C13 and lotus seed pod significantly increased the above three index by 66.26%,114.98% and 257.45%,respectively,while the As content in soil significantly decreased by 21.57%.These results showed that the synergistic effect of lotus seed pod and As(V)reducing strain C13 was better than that of single treatment,and it can be used to strengthen the phytoremediation of P.vittata in As-contaminated soil,which has a certain application prospect.