title: A new insight to adsorption and accumulation of high lead concentration by exopolymer and whole cells of lead-resistant bacterium Acinetobacter junii L. Pb1 isolated from coal mine dump.
abstract: 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-1and it showed antibiotic and multi metal resistance. In aqueous culture, at an initial lead (Pb(II)) concentration of 100 and 500 mg l-1, 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-1) was three times higher than that of bEPS (321.5 mg Pb g-1) and 6.5 times higher than that of whole cells (165 mg Pb g-1). 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.
authors.affiliation: Department of Biotechnology, Motilal Nehru National Institute of Technology, Teliyar Ganj, Allahabad, Uttar Pradesh, India.
authors.forename: Anamika
authors.initials: A
authors.lastname: Kushwaha
authors.affiliation: Department of Biotechnology, Motilal Nehru National Institute of Technology, Teliyar Ganj, Allahabad, Uttar Pradesh, India. radharani@mnnit.ac.in.
authors.forename: Radha
authors.initials: R
authors.lastname: Rani
authors.affiliation: Department of Biotechnology, Motilal Nehru National Institute of Technology, Teliyar Ganj, Allahabad, Uttar Pradesh, India.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Kumar
authors.affiliation: Department of Soil Science, Sam Higginbottom Institute of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India.
authors.forename: Tarence
authors.initials: T
authors.lastname: Thomas
authors.affiliation: Department of Soil Science, Sam Higginbottom Institute of Agriculture, Technology and Sciences, Allahabad, Uttar Pradesh, India.
authors.forename: Arun Alfred
authors.initials: AA
authors.lastname: David
authors.affiliation: Department of Agronomy, Lovely Professional University, Jalandhar, Punjab, India.
authors.forename: Meraz
authors.initials: M
authors.lastname: Ahmed
mesh_terms: D000150:Acinetobacter; D000327:Adsorption; D003031:Coal; D003856:Deoxyuracil Nucleotides; D007854:Lead / Q000378:metabolism*; D012336:RNA, Ribosomal, 16S / Q000235:genetics*
chemical_list: D003031:Coal; D003856:Deoxyuracil Nucleotides; D012336:RNA, Ribosomal, 16S; D007854:Lead; C007267:2'-deoxyuridylic acid
keywords: Acinetobacter junii; Bioremediation; Biosorption; Exopolysaccharide; Lead; Plant growth promoting activity