عنوان مقاله [English]
In this research, heavy metal resistant microorganisms were isolated from several industrial wastewater samples in order to determine their adaptability to metal concentrations higher than MIC. Investigation of these isolates may be used in future wastewater biological treatment processes. For this purpose, two industrial wastewaters were selected and their heavy metal contents, percentage of resistant bacteria, and adaptability of bacteria isolated from each metal to concentrations higher than MIC were determined through cultures on the same metal in each case over long periods of incubation. Our findings indicated that the highest resistance belonged to the Zinc-resistant microorganisms while the lowest belonged to cupper-resistant ones. Also, the zinc-resistant bacteria showed the highest adaptability at zinc concentrations of 16 and 24 mM/L (80%) followed by cupper-resistant bacteria at metal concentrations of 4 mM/L (40%), Cd-resistant bacteria at 12 and 16 mM/L (30%), and finally Pb-resistant ones (around 0%). Compared to results from previous studies, the resistant isolates in the present study showed higher resistance and adaptability.