Diversity Of Endophytic And Rhizosphere Microbial Communities In Heavy Metal-resistant Plants From Gold Mine Tailings Areas

With the vigorous development of mining industry in our country,the exploitation of mineral resources has brought economic benefits while also causing harm to the ecosystem.This article explores in detail the pollution status of heavy metals(As,Cd,Hg,Cr,Cu,Ni,Pb,Zn)in the soil of a tailings dam mining area in Chizhou,and analyzes in detail the effects of heavy metal elements on the rhizosphere microorganisms and endophytic bacteria of five typical vegetation in the mining area.The five plants are ZW1(Cymbopogon citratus),ZW2(Eleusine indica(L.)Gaertn),ZW3(Equisetum hyemale L.),ZW4(Stipa capillata L.),and ZW5(Equisetum ramosissimum Desf.).The specific research results are as follows:The investigation on the pollution of the tailings dam interstitial soil and non-interstitial soil shows that the area is lacking in nutrients and the soil is infertile,with As being the main heavy metal pollutant.The forms of As in the rhizosphere soil are mainly bound to crystalline Fe and Al oxides(CF4)and residual fractions(RS5),accounting for 53%-66%,while the effective forms of As in S2,S3,and S4 are over 40%.The heavy metals present in the plants are mainly As,with the highest accumulation of 27.5 mg/kg,mainly in the roots.ZW1,ZW2,and ZW4 have transfer coefficients <1,which can be used as plants for stable restoration of tailings dam or soil heavy metal pollution.Based on the potential relationship between rhizosphere microorganisms and soil heavy metals,this study explored the diversity of bacteria and fungi in rhizosphere soil of various plants,as well as their correlation with heavy metals.The results showed that the diversity of rhizosphere bacteria was higher than that of non-rhizosphere bacteria,while the diversity of rhizosphere fungi was higher than that of non-rhizosphere fungi.The root system of plants had a certain degree of influence on the microbial community.It was also found that Cd and As had a greater impact on the rhizosphere bacterial community,while Zn and Ni had a greater impact on the rhizosphere fungi community.Based on the influence of heavy metals in soil on endophytic microorganisms in plants,this study explored the diversity of endophytic bacteria and fungi in different tissues of various plants,as well as their correlation with heavy metals.The study found that the diversity of endophytic bacteria was greater than that of rhizosphere bacteria,while the diversity of rhizosphere fungi was greater than that of endophytic fungi.There were significant differences in the diversity of endophytic bacteria and fungi among the roots,stems,and leaves of ZW1.The main bacterial genera in the roots were Actinospica and Acidothermus,while the main genera in the stems were Xanthomonas,Acinetobacter,and Actinospica,and the main genera in the leaves were Xanthomonas,Acinetobacter,and Pseudomonas.Similarly,there were significant differences in the diversity of endophytic bacteria and fungi among the roots,stems,and leaves of ZW5.The main bacterial genera in the roots were Xanthomonas and Actinospica,while the main genera in the stems were Xanthomonas,Acinetobacter,and Ralstonia,and the main genera in the leaves were Xanthomonas,Acinetobacter,and Curtobacterium.Among them,Hg,As,Cr,Cu,and Ni had a greater impact on the endophytic bacterial community,while Cd,Zn,Cr,Cu,and Ni had a greater impact on the endophytic fungi community.Based on the analysis of the symbiotic network and network stability of endophytic bacteria in plants,as well as the impact of microorganisms in the roots,stems and leaves on the overall network stability of plants,this study found that the network stability of plants was in the order of ZW3>ZW4>ZW1>ZW2>ZW5.Based on the comparison of the contribution of network stability of the three parts of the roots,stems and leaves,the network stability of the stems and leaves of ZW1 contributed more,while the network stability of the stems and roots of ZW2 contributed more.The contribution of network stability of the three parts of ZW3 was relatively small,and the contribution of the stem was the highest.The network stability of the roots and stems of ZW4 contributed more,while the network stability of the roots of ZW5 contributed more.This article explores the mechanism of interaction between tailings soil-microorganismsplants,and studies the accumulation of heavy metals in the roots,stems,and leaves of plants,as well as the diversity of rhizosphere microorganisms and endophytic bacteria in plants,after fully understanding the pollution situation in metal mining areas.This provides a theoretical basis and technical support for pollution control and restoration in mining areas.