In Vivo Studies to Elucidate the Role of Extracellular Polymeric Substances from Azotobacter in Immobilization of Heavy Metals
In Vivo Studies to Elucidate the Role of Extracellular Polymeric Substances from Azotobacter in Immobilization of Heavy Metals
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DOI：
10.1021/es900063b
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发表时间：
2009-08-01
影响因子：
11.4
通讯作者：
Juwarkar, Asha A.
中科院分区：
文献类型：
--
作者：
Joshi, Prachi M.;Juwarkar, Asha A.
固氮菌耐重金属菌株产生胞外聚合物的作用。在被重金属污染的土壤中种植的小麦植株对镉(Cd)和铬(Cr)的吸收的限制已经被证明。一株耐重金属的固氮菌。已被分离和鉴定。Cd~(2+)和CrO_4~(2-)的最低抑菌浓度分别为20 mg L~(-1)和10 mg~(-1)。在体外条件下，该菌株产生的EPS能结合15.17+/-0.58mgg(-1)的Cd~(2+)和21.9+/-0.08mgg(-1)的CrO42-。傅立叶变换红外光谱表明，EPS中存在羧基(-COOH)和羟基(-OH)等官能团，主要参与金属离子的结合。在盆栽试验中，将分离的固氮菌菌株以游离细胞和固定化细胞的形式加入到金属污染土壤中。不同处理的固氮菌总数和植物金属浓度与植物Cd(-0.496)和Cr值(-0.455)呈负相关。由此推断，固氮菌属(Azotobacter spp.通过EPS或细胞壁脂多糖(LPS)参与金属离子络合。
The role of extracellular polymeric substances (EPS) produced by the heavy metal-resistant strain of Azotobacter spp. in restricting the uptake of cadmium (Cd) and chromium (Cr) by wheat plants cultivated in soils contaminated with the respective heavy metals has been demonstrated. A heavy metal-resistant strain of Azotobacter spp. was isolated and identified. Minimum inhibitory concentrations (MIC) of Cd2+ and CrO42- were determined to be 20 and 10 mg L-1, respectively. Under in vitro conditions, the EPS produced by the strain could bind 15.17 +/- 0.58 mg g(-1) of Cd2+ and 21.9 +/- 0.08 mg g(-1) of CrO42-, Fourier transform infrared spectra of the EPS revealed the presence of functional groups like carboxyl (-COOH) and hydroxyl (-OH), primarily involved in metal ion binding. Under pot culture experiments, the isolated strain of Azotobacter was added to the metal-contaminated soils in the form of free cells and immobilized cells. The total Azotobacter count and plant metal concentrations under different treatments showed a negative coefficient between the Azotobacter population and plant Cd (-0.496) and Cr (-0.455). Thus it could be inferred that Azotobacter spp. is involved in metal ion complexation either through EPS or through cell wall lipopolysaccharides (LPS).