Effect of different concentrations of metals ions on Bacillus and Pseudomonas spp. isolated from industrial effluents of Faisalabad.

*Corresponding Author Robina Ali robina_ali@ymail.com With the intention to determine effects of different metals on growth of bacteria that were previously identified as heavy metal resistant, total six bacterial samples were selected, repurified and reidentified from the bacterial isolates. Different morphological and biochemical tests were performed that differentiated bacteria into two genera i.e. Bacillus sp. and Pseudomonas sp. Bacteria was grown at pH 7 and temp of 37oC up to incubation time of 96 hours. Three metals (Na, Ca, Zn) were used with concentrations ranged between 25-200 mg/ml. It was found that as the concentrations of metals increased, growth of Bacillus and Pseudomonas spp. firstly increased and then decreased in case of all selected metals. Lowest growth occurred at 200 mg/ml of metal concentration. Optical density at 600 nm was considered as a measure of growth of bacteria. As growth increased, optical density increased and vice versa. Na was found to have a more negative effect on growth of bacterial isolates as compared to other two metals that is, Ca, Zn. Bacillus sp. under investigation was found to be more resistant to these metals as compared to Pseudomonas sp. Both bacterial isolates showed their maximum growth after 72 hours of incubation in most of the cases, afterwards growth decreased. Decreasing resistance pattern for both of bacterial species was as follows; Ca > Zn > Na. The findings revealed the potential application of Bacillus and Pseudomonas spp. for the removal of heavy metals from industrial wastewaters under the conditions where salts of Sodium, Zinc and Calcium are present.