DOI: 10.5176/2251-2489_BioTech15.01
Authors: Prabha Devi, Gomes Samia, Ribeiro Merissa, Deshpande S. Aabha, Singh S Keisham and D’Souza Lisette
Abstract: With urbanization and rapid industrial progress, water bodies around the world are getting highly polluted with metals. Bacteria have evolved several mechanisms to adapt to heavy metal contaminants thus representing a potential source for bioremediation process. The present study deals with isolation, identification and characterization of metal tolerant bacteria (MTB) from the rhizosphere of Eichhornia crassipes (water hyacinth) collected from the backwaters of Cochin (South India, 9o58′N, 76o17′E). Depending on the metals they tolerated (Pb, Cu, Fe, Zn, & Co), the metal tolerant bacteria (MTB) were labeled as Pb-1 to Pb-3, Cu-1 to Cu-4, Fe-1 to Fe-4, Zn-1 to Zn-4, and Co-1 to Co-2. No cultures tolerated and grew in the presence of Hg and Cd. Cultures were identified on the basis of 16S rRNA gene sequence analysis. Morphological and compositional studies were conducted using computer-assisted Scanning Electron Microscopy equipped with Energy Dispersive Spectroscopy (SEM/EDS). The maximum tolerable concentration (MTC) which is the highest concentration having minimum effect on the growth of the isolates were determined and found to be <2mM for CuSO4, <3mM for ZnSO4, <3.5mM for CoCl2, <12mM for PbNO3 and 25mM for FeCl3. They were further screened for antibiotic sensitivity and biological activity according to Kirby-Bauer disc diffusion method. The MTB under metal stress condition showed significant biological activity against clinical pathogens, fouling bacteria and selective plant and fish pathogens indicating their biotechnological application in medicine, agriculture and aquaculture.
Keywords: Rhizosphere; Metal tolerant bacteria; Eichhornia crassipes; biological activity
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