Assessing the impact of heavy metals and antibiotics on bacterial isolates from wastewater treatment plant

The microorganisms isolated from water samples at the wastewater treatment facility Kruševac (Serbia) were screened for resistance to heavy metals and antibiotics. Isolates were identified using morphological and biochemical tests, as well as MALDI-TOF. The resistance to heavy metals was evaluated by determining the minimal inhibitory concentration (MIC) and the minimal microbicidal concentration (MMC) using the microdilution method. The minimal inhibitory concentration and disc diffusion methods were used to assess antibiotic resistance. Isolates were identified as Morganella morganii PMFKG-K1, Klebsiella oxytoca PMFKG-K2, K. oxytoca PMFKG-K3, K. oxytoca PMFKG-K4, Serratia liquefaciens PMFKG-K5, S. liquefaciens PMFKG-K6, Escherichia coli PMFKG-K7, and Bacillus cereus PMFKG-K8. The obtained results indicated that most isolates in planktonic form showed resistance in the presence of heavy metals such as Pb2+ , Zn 2+ , Cu2+ , and Mn2+ , but showed sensitivity in the presence of Cd2+ , Hg2+ , and Cr6+ and antibiotics. All isolates exhibited desirable characteristics for potential use in bioremediation.