Heavy
metal tolerant halophilic bacteria from Vembanad Lake as possible source for
bioremediation of lead and cadmium
M. Sowmya1,
M.P. Rejula1, P.G. Rejith1, Mahesh Mohan1,
Makesh Karuppiah2 and A.A. Mohamed Hatha3*
1School of
Environmental Sciences, Mahatma Gandhi University, Kottayam-686 560, India
2Environmental
Sciences Division, EnviroApps Inc, Orlando, FL? 32835, USA
3Department of
Marine Biology, Microbiology and Biochemistry, Cochin University of Science
and Technology, Cochin ? 682 016, India
*Corresponding
Author E-mail: mohamedhatha@gmail.com
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Publication
Data
Paper received:
26 December 2012
Revised received:
08 June 2013
Accepted:
31 July 2013
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Abstract
Microorganisms
which can resist high concentration of toxic heavy metals are often
considered as effective tools of bioremediation from such pollutants. In the
present study, sediment samples from Vembanad Lake were screened for the
presence of halophilic bacteria that are tolerant to heavy metals. A total of
35 bacterial strains belonging to different genera such as Alcaligenes,
Vibrio, Kurthia, Staphylococcus and members of the family Enterobacteriaceae
were isolated from 21 sediment samples during February to April, 2008. The
salt tolerance and optimum salt concentrations of the isolates revealed that
most of them were moderate halophiles followed by halotolerant and extremely halotolerant
groups. The minimum inhibitory concentrations (MICs) against cadmium and lead
for each isolate revealed that the isolates showed higher MIC against lead
than cadmium. Based on the resistance limit concentration, most of them were
more tolerant to lead than cadmium at all the three salt concentrations
tested. Heavy metal removal efficiency of selected isolates showed a maximum
reduction of 37 and 99% against cadmium and lead respectively. The study
reveals the future prospects of halophilic microorganisms in the field of
bioremediation.
Key
words
Bioremediation,
Halophilic bacteria, Heavy metal tolerance, Sediment,? Vembanad lake
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