Magdy A. Abo- Gharbia
Sohag University, Egypt
Magdy A. Abo- Gharbia is an Assistant professor in Faculty of Science, Sohag University, Egypt.HE obtained his PhD. in Microbiology, Dundee University, Scotland (1989). He has more than 5 publication in various repute journals.
A total of 102 isolates were isolated from nine waste water samples were collected from different contaminated sites at Sohag governorate.-Egypt. Isolates were screened for zinc tolerance and the most tolerant two isolates were identified as Bacillus cereus DAA54 and Pseudomonas aeruginosa DAA86.MICs were 300 and 700 for B. cereus DAA54 and P. aeruginosa DAA86, respectively. Decrease in growth of both isolates (measured in terms of optical density) was observed upon increasing Zn2+ concentration at any given time interval compared controls. Protein profiles detected loss in addition to induction of low molecular weight proteins (96, 89, 63, 50, 44 and 11) KDa as responding to zinc shock. The optimum conditions for biosorption of zinc were investigated by using living and lyophilized biomass of both isolates. The optimum pH values for biosorption rate of zinc were 7.0 and 6.0 for B. cereus DAA54 and P. aeruginosa DAA86. The experimental adsorption data fitted Langmuir and Freundlich isotherm models. The maximum biosorption capacity (q max) values of zinc by the living and lyophilized biomass of B. cereus DAA54 reached 166.67 and 181.81 mgg-1, respectively, and reached 144.93 and 153.85 mgg-1, respectively, for living and lyophilized biomass of P. aeruginosa DAA86. The biosorptive mechanism was confirmed by IR analysis. The high Zn2+ tolerance and biosorption capacity of Bacillus cereus DAA54 and Pseudomonas aeruginosa DAA86 make them candidate organisms for Zn2+bioremoval from aqueous solutions.
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