Resistance of Bacteria Isolated from Otamiri River to Heavy Metals and Some Selected Antibiotics

摘要

This study is aimed at determining the resistance of bacteria to heavy metals and some antibiotics. The ability of aquatic bacteria isolates from Otamiri River at Ihiagwa in Owerri North, Imo State to tolerate or resist the presence of certain selected heavy metals: Pb+, Zn2+ and Fe2+ and some antibiotics was investigated. Identification tests for the bacteria isolates from Otamiri River revealed them to belong to the genera Pseudomonas, Aeromonas, Bacillus, Escherichia, Micrococcus and Proteus species. The control experiment showed heavy growth of the organisms. These bacteria strains were checked for resistance against heavy metals by culturing them in basal medium in which varying concentrations of heavy metal compounds was incorporated. All the bacteria strains showed resistance against heavy metals with Minimal Inhibitory Concentration (MIC) values ranging from 0.1 to 3.0 mg/L, respectively. Generally, all the organisms had low MIC values for Pb+ and high MIC value for Zn2+ and Fe2+. This indicates average and low toxicity respectively of the heavy metals to the organisms. On the other hand, the isolates also exhibited high tolerance to most of the antibiotics like Gentamycin (77.7%), Rifampicin (66.0%) and Oflaxacin (57.3%). The ability of these organisms to resist the presence of both metals and antibiotics could present some very serious health implication because of the ability of these organisms to pass these resistant genes via R-plasmids to the next cell around will affect a whole bacterial population thereby complicating treatment.