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Abstract
Twenty three bacterial strains have been isolated from polluted water and soil samples of Ismailia Canal in Egypt. The polluted sites were at Abu Zabal Factory (fertilizer factory), Elshaba factory (Aluminum sulfate factory) and Oil-pipes Company (petrochemical materials). By screening the abilities of these isolates to tolerate heavy metals, it has been found that isolate ”MAM-4” was the most potent isolate. This isolate was identified as Providencia rettgeri.
As the concentration of Al3+ increased the ability of P. rettgeri to uptake Al3+ decreased. P. rettgeri could remove 97.2% of Al3+ from 25 mg/L. Bacillus cereus ATCC 11778 (American Type Culture Collection, U.S.A) gave the same trend for Al3+ uptake but P. rettgeri was more tolerant to Al3+ than B. cereus ATCC 11778.With increasing Co2+ concentration, abilities of P. rettgeri and B. cereus ATCC 11778 to uptake decreased. P. rettgeri could uptake 59 mg/L Co2+ from 200 mg/L (29.5%), while B. cereus ATCC 11778 uptake 68.3mg/L (34.1%).
Also, as the concentration of Cu2+ increased the abilities of P. rettgeri and B. cereus ATCC 11778 to uptake Cu2+ decreased. P. rettgeri removed 11.5mg/Cu2+ from 25mg/L (47.0%), while B. cereus ATCC 11778 removed 13.5mg/L from the some concentration (54.%).
Combined treatment of 1.0% untreated clay with P. rettgeri could remove 471.8 mg/L Al3+ from 500 mg/L (94.4%), 82.4 mg/L Co2+ from 200 mg/L (41.2%) and 150 mg/L Cu2+ from 300 mg/L (50%).
However, 1.0 % treated clay combined with P. rettgeri adsorbed 207.8 mg/L Al3+from 500 mg/L (41.5%), 52.0 mg/L Co2+ from 200 mg/L (26.0%) and 185 mg/L Cu2+ from 300 mg/L (61.6%).
The combined treatment adsorbed more heavy metals than clay only or bacterial cells only. Three KGy gamma radiations reduced the viable count of P. rettgeri by 7.4 log cycles. P. rettegri mutant MI was able to tolerate more Al3+ than the parent strain.
Key words: P. rettgeri, heavy metals, clay and gamma radiation.