Isolation, characterization of heavy metal resistant strain of Pseudomonas aeruginosa isolated from polluted sites in Assiut city, Egypt

Sixty six isolates of Pseudomonas spp. were isolated from wastewater of El-Malah canal located in Assiut, Egypt and were checked for their heavy metal tolerance. One isolate has tested for its multiple metal resistances and found to be plasmid mediated with molecular weight 27 Kb for nickel and lead. It was identified as Pseudomonas aeruginosa ASU 6a. Its minimal inhibitory concentration (MIC) for Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺, Cr³⁺, Cd²⁺and Pb²⁺ were 6.3, 5.9, 6.8, 9.2, 5.8, 4.4, and 3.1 mM, respectively. Growth kinetics and the maximum adsorption capacities were determined under Ni²⁺ and Pb ²⁺ stress. The latter heavy metals induced potassium efflux and were used as indicator for plasma membrane permeabilization.