, Volume 23, Issue 5, pp 775–783 | Cite as

Biological characterization of lead-enhanced exopolysaccharide produced by a lead resistant Enterobacter cloacae strain P2B

  • Milind Mohan Naik
  • Anju Pandey
  • Santosh Kumar Dubey
Original Paper


A lead resistant bacterial strain isolated from effluent of lead battery manufacturing company of Goa, India has been identified as Enterobacter cloacae strain P2B based on morphological, biochemical characters, FAME profile and 16S rDNA sequence data. This bacterial strain could resist lead nitrate up to 1.6 mM. Significant increase in exopolysaccharide (EPS) production was observed as the production increased from 28 to 108 mg/L dry weight when exposed to 1.6 mM lead nitrate in Tris buffered minimal medium. Fourier-transformed infrared spectroscopy of this EPS revealed presence of several functional groups involved in metal binding viz. carboxyl, hydroxyl and amide groups along with glucuronic acid. Gas chromatography coupled with mass spectrometry analysis of alditol-acetate derivatives of acid hydrolysed EPS produced in presence of 1.6 mM lead nitrate demonstrated presence of several neutral sugars such as rhamnose, arabinose, xylose, mannose, galactose and glucose, which contribute to lead binding hydroxyl groups. Scanning electron microscope coupled with energy dispersive X-ray spectrometric analysis of this lead resistant strain exposed to 1.6 mM lead nitrate interestingly revealed mucous EPS surrounding bacterial cells which sequestered 17 % lead (as weight %) extracellularly and protected the bacterial cells from toxic effects of lead. This lead resistant strain also showed multidrug resistance. Thus these results significantly contribute to better understanding of structure, function and environmental application of lead-enhanced EPSs produced by bacteria. This lead-enhanced biopolymer can play a very important role in bioremediation of several heavy metals including lead.


Exopolysaccharide Lead Resistance Bacteria Bioremediation 



Milind Naik gratefully acknowledges UGC, Government of India for financial support as Junior Research Fellowship. The authors are also thankful to Dr. M. S. Prasad and Mr. Vijay Khedekar from National Institute of Oceanography, Goa, India for scanning electron microscopy.

Supplementary material

10532_2012_9552_MOESM1_ESM.doc (96 kb)
Supplementary material 1 (DOC 95 kb)


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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Milind Mohan Naik
    • 1
  • Anju Pandey
    • 1
  • Santosh Kumar Dubey
    • 1
  1. 1.Laboratory of Bacterial Genetics and Environmental Biotechnology, Department of MicrobiologyGoa UniversityPanajiIndia

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