一株铅镉抗性菌株WS34的生物学特性及其对植物修复铅镉污染土壤的强化作用

Isolation and characteristics of heavy metal-resistant strain WS34 and its effects on the phytoremediation of soils contaminated with lead and cadmium

从土壤样品中筛选出一株对碳酸铅、碳酸镉活化能力最强的铅镉抗性细菌WS34,并研究其生物学特性.经生理生化特征及16SrDNA序列分析,菌株WS34被鉴定为伯克霍尔德氏菌属(Burkholderiasp.WS34).菌株WS34对多种重金属和抗生素具有抗性,具有溶磷、分泌吲哚乙酸、产生铁载体和ACC脱氨酶的能力,并对温度、pH、盐浓度具有一定耐受性.利用盆栽试验研究了菌株WS34、EDTA及EDTA和WS34复合3种处理下对印度芥菜和油菜生长及富集铅镉能力的影响.结果表明,菌株WS34能促进供试植物生长,使印度芥菜和油菜的干重分别比对照增加21.4%～76.3%和18.0%～236%,铅镉积累量比对照增加9.0%～46.4%和13.9%～329%,且油菜中的增加量大于印度芥菜.EDTA能使印度芥菜和油菜的铅镉积累量比对照分别增加25.1%～475%和10.1%～84.5%.0.5mmol.kg-1EDTA+菌株WS34的复合处理下,植物的重金属吸收量与EDTA处理相当甚至高于EDTA处理.

Microbe-enhanced phytoremediation has been considered as a promising measure for the remediation of heavy metal-contaminated soils. In this study, the lead and cadmium-resistant bacterium WS34 was isolated from heavy metal-contaminated soil and identified as Burkholderia sp. WS34 based on the analysis of its physical and biochemical characteristics and its 16S rDNA gene sequence. The biological characteristics of the strain WS34 were also characterized. The effects of the strain WS34 and ethylenediaminetetraacetic acid （EDTA） or their combination on the growth and heavy metal accumulation by India mustard and rape were evaluated in pot experiments. Strain WS34 could produce indole acetic acid （IAA） , a siderophore, and 1-aminocyclopropane-1-earboxylate deaminase. It could also solubilize inorganic phosphate. Strain WS34 also showed resistance to high levels of heavy metals and antibiotics and solubilized carbonic lead and carbonic cadmium. Strain WS34 was temperature resistant and pH and salt tolerant. Inoculation with strain WS34 promoted the plant growth and the accumulation of Pb and Cd in root and shoot tissues. Compared to the non-inoculated control, the dry weights of the India mustard and rape treated with strain WS34 were increased from 21.4% to 76.3% and from 18.0% to 236% and the Pb and Cd contents of the India mustard and rape increased from 9.0% to 46.4% and from 13.9% to 329% , respectively. The Pb and Cd contents of the India mustard and rape treated with EDTA were increased from 25.1% to 475% and from 10.1% to 84.5% , respectively compared to the control. Treatment with the combination of one-half dose of the tested bacterium and EDTA helped the plants to accumulate the same or more Pb and Cd compared to the EDTA treatment alone.