接种耐镉细菌对青葙吸收积累土壤中镉的影响

Effect of Cd-tolerance bacterium inoculation on Cd uptake in soil by Celosia argentea

于广东省大宝山尾矿区发现1种镉含量较高的植物——青葙(Celosia argentea),将其幼苗种植于不同浓度的镉污染土壤中培养,研究其镉吸收特性。结果表明,青葙可耐受浓度为40 mg·kg-1以上的镉污染,且植株内镉含量随土壤镉浓度的增加而升高。通过在培养基中加入不同浓度的镉(Cd Cl2·2.5H2O),从镉超富集植物龙葵(Solanum nigrum)叶片中筛选到1株耐受镉浓度达200 mg·L-1的内生细菌DE5,经生理生化试验和16S r DNA序列分析,将其鉴定为争论贪噬菌(Variovorax paradoxu),Genbank登录号为KF051781。温室内设置盆栽试验,以灌根的方式接种DE5发酵液,通过对青葙株高、生物量及镉含量的测定,研究接种内生菌对青葙吸收镉的影响,结果表明,接菌处理的青葙根部干重相比于对照增加125.0%,地上部和全株的镉吸收总量分别增加81.7%和81.1%。研究表明,青葙是一种良好的镉污染土壤修复的植物资源,接种DE5能够强化青葙的镉吸收效果,其作用效果好于浇施螯合剂EDTA,具有一定的应用潜力。

A superior cadmium（ Cd）-tolerance plant Celosia argentea was screened from a mining area in Dabao Mountain,Guangdong Province. The Cd absorption capacity of the plant was studied by cultivating its seedlings in soil with different concentrations of Cd. The results showed that the C. argentea was able to tolerate Cd at the concentrations higher than 40 mg · kg-1in soil. Moreover,the content of Cd in the C. argentea was positively correlated with the Cd concentration in a certain range in soil. With different concentrations of Cd（ Cd Cl2·2. 5H2O） added into the mediums,a strain of endophytic bacteria DE5 capable of tolerating Cd at a high concentration of 200 mg·kg-1was sifted from the leaves of Solanum nigrum,a kind of Cd hyperaccumulator, which was identified as Variovorax paradox（ Genebank accession number：KF051781） by physiological and biochemical experiments and 16 S r DNA sequence analysis. The C. argentea root-irrigated by DE5 fermentation broth was cultivated in the soil with a higher concentration（ 100 mg·kg-1） of Cd in a pot experiment,and the plant height,biomass and Cd absorption capability were analyzed. The results showed that the dry weight of C. argentea treated with DE5 increased by 125. 0% compared with the control,and noticeably,the total Cd absorbed by the aerial part and whole plant increased by 81. 7% and 81. 1%,respectively. Our study indicated that the C. argentea was a superior botanic resource conducive to the remediation of Cd-polluted soil. It is feasible and potentially applicable to inoculate DE5 into the rhizosphere of C. argentea,whose effect showed advantages over that of pouring the chelating agent EDTA.