铅镉抗性菌株JB11强化植物吸收污染土壤中铅镉的研究

Abstract

研究了铅、镉抗性菌株 （JB11）和生物降解螯合剂乙二胺二琥珀酸（S，S）-EDDS）提高高羊茅和红三叶草吸收土壤中铅、镉的能力。从土壤样品中筛选出1株对Cd、Pb具有较强抗性的菌株JB11，经鉴定为成团泛菌属（<em>Pantoea agglomerans</em>）。JB11对Pb²⁺ 、Cd²⁺、Cr⁶⁺ 、Cu²⁺ 、Zn²⁺、Ni²⁺等多种重金属和卡那霉素、氨苄青霉素、链霉素、四环素等抗生素具有抗性， 在温度 15-35℃和 pH 为 5.0-9.0范围内生长良好，最适生长温度为30℃，最适 pH值为7.0左右，在低于 3%的 NaCl浓度下生长良好。盆栽试验研究了菌株JB11、EDDS及1/2EDDS+JB11 3种处理下对生长在Cd 100 mg/kg 、Cd 200 mg/kg 、Pb 500 mg/kg 和 Pb 1000 mg/kg的土壤中的高羊茅和红三叶生长及从土壤富集Cd、Pb能力的影响。结果表明，外加JB11能使高羊茅和红三叶的干重分别比对照都有增加。除外加JB11后在经Pb 1000 mg/kg处理的土壤中高羊茅地上部的Pb浓度、经Cd 200 mg/kg处理的土壤中红三叶地上部的Cd浓度以及经Cd 100 mg/kg处理的土壤中高羊茅和红三叶根部的Cd浓度以外，外加JB11后对其他重金属处理植物中Pb和Cd的含量都显著增加。外加EDDS后除在经Pb 500 mg/kg的土壤中高羊茅根部的Pb浓度增加差异不显著，对其余重金属处理都可产生显著的影响 （<em>P</em> < 0.05）。1/2EDDS+JB11的复合处理下植物重金属吸收量多数高于JB11和EDDS单独处理，JB11用于植物修复土壤Pb和Cd污染具有很大的潜力。;We investigated the abilities of a Pb- and Cd-resistant bacterial strain (JB11) and the biodegradable chelator ethylenediamine dissociate ([S,S]-EDDS) to improve the absorption of Pb and Cd from soil by tall fescue and red clover. JB11 was isolated from contaminated soil samples and analyzed for Pb- and Cd-resistance. JB11 was identified as <em>Pantoea agglomerans</em>. Studies of the biological characteristics of JB11 showed that it is generally resistant to heavy metals, including Cd²⁺, Cr⁶⁺, Cu²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ and that it is also resistant to antibiotics, such as ampicillin, kanamycin, streptomycin, and tetracycline. Strain JB11 grows well at temperatures between 15 and 35℃, pH values of 5.0-9.0, and NaCl concentrations below 3%. The optimum temperature for JB11 is 30℃ and the ideal pH value is approximately 7.0. Tall fescue and red clover were grown in pots with soil containing Cd at 100 mg/kg, Cd at 200 mg/kg, Pb at 500 mg/kg, or Pb at 1000 mg/kg, to which were added JB11, EDDS, a combination of JB11 and EDDS, or water. Pot experiments were performed to study the effects of JB11 and EDDS on the abilities of tall fescue and red clover to take up Cd and Pb from the soil and on their growth. The amounts of biomass produced by tall fescue and red clover were significantly higher in the JB11 treatments than in the untreated control plants. The Pb and Cd concentrations were significantly higher (<em>P</em><0.05) in the JB11-treated plants than in the control plants, with the exception of the Pb concentration in the above-ground parts of tall fescue growing in soil containing Pb at 1000 mg/kg, the Cd concentration in the above-ground parts of red clover growing in soil containing Cd at 200 mg/kg, and the Cd concentrations in tall fescue and red clover roots in soil containing Cd at 100 mg/kg. The Pb and Cd concentrations were significantly higher (<em>P</em> < 0.05) in the EDDS-treated plants than in the control plants, with the exception of the Pb concentrations in the tall fescue roots in soils containing Pb at 500 mg/kg. The Pb and Cd concentrations in the tall fescue and red clover increased in response to the combined EDDS and JB11 treatment. The amounts of Pb and Cd absorbed by the plants were higher in most of the combined (1:1) EDDS- and JB11-treated plants than in the plants treated with only EDDS or only JB11. JB11 is Pb- and Cd-resistant, and its application to the soil improved the net uptake of Pb and Cd from the soil by the experimental plants. There is, therefore, great potential for viable phytoremediation using JB11.