Author(s): S. Sharmila Begum1* and A. Aundhati2
The present study is findings of an investigation of heavy metal tolerance in Pseudomonas sp R2- KJ461965, a phenol resistance and organophosphate 17 degrading isolate. Metal impregnated paper discs at 0.2 mg/ml concentration were used to evaluate oligodyanamic action in vitro. Growth of the isolate in the paper disc assay and development of biofilm at late stage of culture growth, was a clear evidence of resistance and biosorption mechanism. In liquid culture method, the culture media was spiked with heavy metals viz. lead, mercury, cobalt, copper, zinc, calcium and magnesium, at concentration ranging from 0.5 to 2 mg/ml. The tolerance to metals were ascertained by increase in biomass with increase in metal concentration. Plasmid curing was carried out to locate the genes responsible for tolerance to plasmid or chromosome. Ethidium Bromide (100 µg/ml) and 2 % SDS were used as curing agent. The isolate was found to be resistance to lead, chromium, magnesium zinc, calcium and copper and tolerant to cobalt, mercury and iron. Loss of heavy metal resistance from the isolated strain after plasmid curing confirmed a relationship between heavy metal resistance with plasmid. These findings indicates the novelty of the strain in bioremediation of heavy metals contamination.