Kushwaha Anamika, Rani Radha, Kumar Sanjay, Thomas Tarence, David Arun Alfred, Ahmed Meraz
Department of Biotechnology, Motilal Nehru National Institute of Technology, Teliyar Ganj, Allahabad, Uttar Pradesh, India.
Department of Soil Science, Sam Higginbottom Institute of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India.
Environ Sci Pollut Res Int. 2017 Apr;24(11):10652-10661. doi: 10.1007/s11356-017-8752-8. Epub 2017 Mar 11.
A lead-resistant bacterial strain was isolated from coal mine dump and identified as Acinetobacter junii Pb1 on basis of 16S rRNA (ribosomal ribonucleic acid) gene sequencing. The minimum inhibitory concentration of lead for the strain was 16,000 mg l and it showed antibiotic and multi metal resistance. In aqueous culture, at an initial lead (Pb(II)) concentration of 100 and 500 mg l, lead adsorption and accumulation by the isolate was 100 and 60%, at pH 7 at 30 °C after 48 and 120 h, respectively. The two fractions of exopolysaccharide (EPS), loosely associated EPS (laEPS) and bound EPS (bEPS), and whole cells (devoid of EPS) showed high binding affinity towards Pb(II). The binding affinity of laEPS towards Pb(II) (1071 mg Pb g) was three times higher than that of bEPS (321.5 mg Pb g) and 6.5 times higher than that of whole cells (165 mg Pb g). The binding affinity of EPS and whole cells with Pb(II), reported in the current study, is considerably higher as compared to that reported in the literature, till date. SEM analysis, showed an increase in thickness of cells on exposure to Pb(II) and TEM analysis, revealed its accumulation (interior of cell) and its adsorption (with the external cell surface). The isolate was also found to be positive for indole acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase production which helps in promoting plant growth. Thus, this study provides a new understanding towards Pb(II) uptake by A. junii Pb1, highlighting its potential on the restoration of Pb(II) contaminated repositories.
从煤矿废弃物中分离出一株抗铅细菌菌株，基于16S rRNA（核糖体核糖核酸）基因测序将其鉴定为琼氏不动杆菌Pb1。该菌株对铅的最低抑菌浓度为16,000 mg/L，且表现出抗生素和多金属抗性。在水培中，初始铅（Pb(II)）浓度为100和500 mg/L时，该分离株在30°C、pH 7条件下分别培养48和120小时后，对铅的吸附和积累率分别为100%和60%。胞外多糖（EPS）的两个组分，即松散结合的EPS（laEPS）和结合的EPS（bEPS）以及完整细胞（不含EPS）对Pb(II)表现出高结合亲和力。laEPS对Pb(II)的结合亲和力（1071 mg Pb/g）是bEPS（321.5 mg Pb/g）的三倍，是完整细胞（165 mg Pb/g）的6.5倍。与迄今文献报道相比，本研究报道的EPS和完整细胞与Pb(II)的结合亲和力要高得多。扫描电子显微镜（SEM）分析表明，暴露于Pb(II)后细胞厚度增加，透射电子显微镜（TEM）分析显示其在细胞内积累以及在细胞外表面吸附。还发现该分离株吲哚乙酸（IAA）和1-氨基环丙烷-1-羧酸（ACC）脱氨酶产生呈阳性，这有助于促进植物生长。因此，本研究为琼氏不动杆菌Pb1对Pb(II)的吸收提供了新的认识，突出了其在修复Pb(II)污染储存库方面的潜力。
