TOLERANCE OF ENVIRONMENTAL BACTERIA TO HEAVY METALS

Abstract

The aim of this study was to isolate microorganisms with bioremediation potential from soil contaminated with heavy metal compounds, and to analyze the tolerance of these microorganisms to various heavy metal concentrations. In total, 7 bacterial strains were isolated and cultivated. The sensitivity of microorganisms to heavy metals proved to be dependent on the type of medium. The use of liquid media during the 8-hour and 24-hour toxicity tests resulted in reduced tolerance of isolates to the concentrations of selective factors used, relative to culture on solid substrates. In addition, optical density increases in the bacterial cultures have been observed at the highest concentrations of some heavy metals. Briefly, during the 48-hours test 3 strains showed increased optical density values in the presence of 1 mM copper sulfate and 2 strains displayed this ability also in the presence of 1 mM cadmium sulfate and lead nitrate.