Effect of heavy metals and some selected antibiotics on bacteria isolated from Shatt Al-Arab River

Abstract EN

This study is carried out to determine the effect of heavy metals and some antibiotics on bacteria and study the ability of aquatic bacteria isolated from Shatt Al- Arab River to tolerate or resist the presence of certain selected heavy metals : Pb+, Zn2+ and Fe2+ and some antibiotics.

Identification tests for the bacterial isolates revealed them to the genera Pseudomonas, Aeromonas, and Proteus species.

These bacteria strains are checked for resistance against heavy metals by culturing them in basal medium in which varying concentrations of heavy metal compounds were incorporated.

All the bacteria strains show resistance against heavy metals with Minimal Inhibitory Concentration (MIC) values ranging from (0.5-2.25 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 (87.8 %), Rifampicin (75.0 %) and Oflaxacin (62.0 %).

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.