拉恩氏菌诱导重金属磷酸盐沉淀及其在土壤中的活性变化特征

Induction of Heavy Metal Phosphate Precipitation by Rahnella sp.and Its Activity Changes in Soil

微生物可通过诱导形成磷酸盐沉淀来固定土壤中的有效态铅(Pb),在Pb污染土壤修复方面越来越受到人们的重视,但对其诱导的磷酸盐沉淀在土壤中的活性变化特征缺乏了解。研究了1株拉恩氏菌LRP3对单一Pb和Cu-Pb复合磷酸盐沉淀的诱导作用,并通过土壤培养和盆栽试验研究了2种磷酸盐沉淀中的Pb在土壤中的释放及小白菜对其吸收特征。结果表明:菌株LRP3发酵液能够快速去除溶液中单一或与Cu^(2+)共存的Pb^(2+),分别诱导形成呈不规则块状的Pb(H_(2)PO_(4))_(2)晶体和小球形的Pb(H_(2)PO_(4))_(2)-Cu_(3)(PO_(4))_(2)复合晶体。短时土壤培养条件下,复合晶体中的Pb稳定性高,不易活化,而单一晶体中的Pb稳定性较差,容易活化,土壤微生物能够促进其活化。单一和复合磷酸盐晶体可在小白菜根际土壤中释放出Pb,增加小白菜叶子和根中Pb的含量,与对照土壤相比,小白菜叶子和根对Pb的富集系数分别下降了62.50%,78.75%和75.50%,83.75%。因此,菌株LRP3在Pb污染土壤修复方面有重要的应用价值,并且可通过向土壤中添加Cu^(2+)来强化修复效果。

Microorganisms can immobilize available lead(Pb)in soil by inducing the formation of phosphate precipitation,which has received increasing attention in the remediation of Pb contami⁃nated soil.However,the characteristics of activity changes of phosphate precipitation induced by these microorganisms in soil are not well understood.The induction of single Pb and Cu-Pb com⁃bined phosphate precipitation was studied by Rahnella sp.LRP3,and soil culture and pot experi⁃ment were carried out to reveal the release and uptake by pakchoi of Pb in the phosphate precipita⁃tion.The results showed that strain LRP3 fermentation broth could rapidly remove Pb^(2+)in the solu⁃tion when it was alone or coexisted with Cu^(2+),which led to formation of Pb(H_(2)PO_(4))_(2) crystal with shape of irregular block and Pb(H_(2)PO_(4))_(2)-Cu_(3)(PO_(4))_(2) composite crystal with shape of small sphere,respec⁃tively.Under the condition of short-term soil culture,the stability of Pb in composite crystal was high and Pb in it was not easily activated,while the stability of Pb in single crystal was relatively poor and could be activated,which could be promoted by soil microorganism.Single and composite phosphate crystals could release Pb in the rhizosphere soil of pakchoi,increasing Pb content in leaves and roots of pakchoi.Compared with the control soil,the enrichment coefficients of Pb in the leaves and roots of pakchoi decreased by 62.50%and 78.75%,75.50%and 83.75%,respectively.Therefore,strain LRP3 has important application value in Pb contaminated soil remediation,and the remediation effect can be enhanced by adding Cu^(2+)into the soil.