Heavy metal resistant of E. coli isolated from wastewater sites in Assiut City, Egypt.

Twelve isolates of E. coli 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 weights 27 and 65 kb for hexa- and trivalent chromium. It was identified as E. coli ASU 7. Its minimal inhibitory concentration (MIC) for Cu(2+), Co(2+), Ni(2+), Zn(2+), Cr(6+), Cr(3+), Cd(2+) and Pb(2+) were 1.57, 2.55, 1.7, 9.17, 0.48, 7.69, 4.4 and 3.1 mM, respectively. Growth kinetics was determined under Cr(6+) and Cr(3+) stress. SDS-PAGE of protein profile shows that 10 ppm (0.19 mM) of Cr(6+) induces new protein with molecular weight 23 kDa.