Resistance to antibiotics and ability to tolerate heavy metals in bacteria isolated from Razi industrial wastewater treatment plant and effluent of refinery units in Isfahan, Iran

Industrial activities present a significant threat to the environment and natural ecosystems like water and soil due to the release of toxic metals. This article primarily concentrates on the identification and isolation of bacteria, with the goal of effectively eliminating pollutants from industrial wastewater. In order to achieve this goal, the study was conducted to assess the ability of bacterial strains to tolerate copper (Cu) and zinc (Zn), as well as their antibiotic resistance and ability to tolerate elevated metal concentrations. The resistance of the isolates to various metals and antibiotics were assessed using the minimum inhibitory concentration (MIC) values and disc diffusion (DD) method, respectively. The technique of colony PCR was employed to determine the identity of the bacteria that were separated. Resistance to multiple antibiotics was assessed, including Penicillin, Sulfamethoxazole, Tetracycline, Erythromycin, Amoxicillin, Cefoxitin, Streptomycin, Chloramphenicol, Vancomycin, Gentamycin, Cephalothin, Rifampicin, and Novobiocin. In the current investigation, a total of ۵ bacteria with a positive gram stain and ۷ bacteria with a negative gram stain were identified. The study found that the effluent from the wastewater treatment plant in Razi industrial town showed resilience to copper ions, especially at a concentration of ۷mM. The effluent wastewater from the refinery unit exhibited the greatest level of tolerance towards zinc, with a concentration as high as ۶mM. The rise in copper and zinc levels in industrial wastewater treatment plants causes microorganisms to develop resistance to these heavy metals. The study of Gram-positive resistant bacteria conducted in this research focused on the examination of their susceptibility to zinc and copper. Notably, Staphylococcus hominis displayed resistance to a majority of the antibiotics evaluated. However, Kocuria rosea demonstrated sensitivity to all antibiotics. Agrobacterium fabrum exhibited susceptibility to all antibiotics as opposed to other Gram-negative bacteria resistant to zinc and copper. The findings of this study indicated that some strains displayed a degree of resistance to both antibiotics and heavy metals. The presence of heavy metals in bacteria isolated from a wastewater treatment plant exhibited the capability to restrict antibiotic resistance.

Keywords:

Antibiotic resistance , Industrial effluent , Colony PCR , Heavy metal-resistant bacteria