A REVIEW ON DIVERSITY OF CHROMIUM RESISTANT BACTERIAL STRAINS ISOLATED FROM TANNERY INDUSTRY

PRATIBHA RANI¹*, SEEMA P. UPADHYE^2
1Mewar University, Gangrar, Chittorgarh, Rajasthan, India
²Mewar University, Gangrar, Chittorgarh, Rajasthan, India
* Corresponding Author : pbr.july@gmail.com

Received : 05-05-2016     Accepted : 06-10-2016     Published : 28-10-2016
Volume : 8     Issue : 11       Pages : 797 - 803
Int J Microbiol Res 8.11 (2016):797-803

Keywords : Chromium, Chrome liquor, Tannery effluents, CMBL Crl3, 16S rRNA, 16S rDNA.
Academic Editor : David Buckley, Dr Mukta Sharma
Conflict of Interest : None declared
Acknowledgements/Funding : None declared
Author Contribution : None declared

Chromium is a naturally occurring element found in rocks, animals, plants, soil, and in volcanic dust and gases. Chromium is present in the environment in several different forms. Most leather is chrome-tanned. All wastes containing chromium are considered hazardous by the U.S. Environmental Protection Agency. These irregularities have had a disastrous economic, social and health impacts. Chrome liquor is generally used for tanning purpose. When chrome liquor is discharged with effluents into the environment, they contain chrome salts in excess of the maximum permissible limits. In biological system, enrichment of chromium-resistant bacteria is formed by sludge deposition from such effluents. The present study shows the diversity of chromium resistance bacteria/strains isolated from tannery effluents in past decades by researchers. Our literature review found a high chromium tolerance among isolated bacteria ranging from 10µg/ml-45000µg/ml. CMBL Crl3 exhibited the highest resistance to chromium. Isolates were screened and characterized with biochemical and 16S rRNA based sequencing methods. There are few reports are available for characterization by using 16S rDNA sequencing methods, but 16S rDNA sequencing has played a significant role in the accurate identification of bacterial isolates (its amplicon product shows highly and less conserved region but in case of 16S rRNA amplicon shows only highly conserved stretches in bacteria) and particularly important in the case of bacteria with unusual phenotypic profiles, rare bacteria, slow-growing bacteria, uncultivable bacteria and culture-negative infections. Identification of microbes related technology might provide an alternative or addition to conventional method of metal removal or metal recovery. The identified chromium resistant bacteria would be useful for bioremediation of heavy metal contaminated tannery effluent. In transferring this technology from laboratory to a large-scale application, better understanding of all these aspects is necessary. Hence, this developing biotechnological method that encompasses fields from genetic engineering to reactor engineering demands focused research in these directions, which may lead to implementation of this technology on a larger scale and drive it toward being the most opted-for technology.