| Heavy metals are widely found in the environment, which originate fromhuman activities in production, such as metal smelting, irrigation, and mining. Theheavy metal not only affects the soil environment, thus decreasing the yield andquality of the crops, but also deteriorates the water, even accumulates in the humanbody through the food chains, which will endanger the health. Phytoremediation isa green?effective and economical choice of soil treatment?but it often hasproblems such as slowgrowth and long repair period. Adding microbe can enhancethe effect of phytoremediation, make up for the deficiency of phytoremediation,and improve the efficiency of phytoremediation.So plant-microbe uniteremediation has a certain prospect of application to ameliorate soil polluted byheavy metals.Pot experiments were performed to study the enhancement effects of microbeon the Cr absorption by hyperaccumulator Leersia hexandra Swartz.TheCr-resistant rhizobacteria and endophytic were isolated from the plant rhizosphereand Leersia hexandra Swartz.The results showed:Then a consolidated remediation pot experiment was conducted to examinethe enhancement effect of the three strains each and together on the growth and Crabsorption of Leersia hexandra Swartz of different Cr concentrations.The testindicated both rhizobacteria and endophytic could strengthen the Cr absorptionfrom soil of Leersia hexandra Swartz.Under Cr concentration of200mg/kg,the Crcontents in the aboveground parts of Leersia hexandra Swartz land treated withstrain WYHN16?WG38?GJH45and three strains together increased by110.33%?71.75%?140.81%and176.96%respectively,compared with the control.Thesample had reached significance levelcompared with the control. The Cr contentsof whole plant had increased up to119.69%. Under Cr concentration of400mg/kg,land treated with strains also showed obvious effect.The Cr contents in theaboveground parts of Leersia hexandra Swartz land treated with strain WG38andthree strains together increased by62.73%and119.47%respectively,comparedwith the control. The Cr contents in theroot of Leersia hexandra Swartz landtreated with three strains together increased by106.25%,compared with the control.The Cr contents of whole plant land treated with strain WG38and three strainstogether increased by60.31%and116.14%respectively, compared with thecontrol.Three Cr-resistant strains were screened out by investigating the ability of producing ACC deaminase, IAA, oxalic acid, lactic acid and other organic acidscomprehensively. According to the morphological and physiological characteristics,and the gene sequence of16S rRNA, the rhizobacteria GJH45and WG38wereidentified as Bacillus licheniformis and Bacillus cereus, theendophytic WHYN16were Microbacteriumnatoriense.A kind of plant named Leersia hexandra Swartz is found by consultingliterature, which could resist and accumulate Cr.The seed was bought andraised.Then pot experiments were performed to study the Cr absorption byhyperaccumulator Leersia hexandra Swartz.The result showed Cr concentration of200mg/kg had little effect to Leersia hexandra Swartz. The Cr contents inLeersiahexandra Swartzwas tested using ICP-AES after60days growing.It showed the Crcontents of Leersia hexandra Swartz was up to9240mg/kg.The part above groundwas up to3500mg/kg,a well above the standard people think of Crhyperaccumulator(the part above ground was up to1000mg/kg).It showed Leersiahexandra Swartz really had a well ability of Cr absorption,even in ShenZhen.104Cr-resistant strains were isolated from the root, stem,leaf of Leersiahexandra Swartz and the rhizosphere soil, including forty-seven from therhizosphere soil and fifty-seven from Leersia hexandra Swartz.Based on thephylogenetic analysis of the16S rRNA sequence,the Cr-resistant strains weremainly belonged to Bacillus sp., Shigella sp., Cupriavidus sp., Pseudomonas sp.,Rhodococcus sp.,Brevibacterium sp. and Microbacterium sp.,especially Bacillus sp.and gram positive bacteria is the most. |
PDF Full Text Request