Inhibition of iron oxidation inThiobacillus ferrooxidans by toxic metals and its alleviation by EDTA

Abstract

Oxidation of ferrous iron and growth ofThiobacillus ferrooxidans are severely affected in the presence of toxic metals, but the iron-oxidizing system of this bacterium is less sensitive to toxic metals than is its growth. Mercury toxicity is much more pronounced than that of uranium and cadmium. Iron oxidation is completely inhibited at 0.1 part/106 of mercury, which is 5000 and 20,000 times less than the minimum inhibitory concentration of uranium and cadmium respectively. The extent of antagonism between EDTA and toxic metal during iron oxidation by this bacterium is specific for a particular metal as well as the concentration used in the medium. Use of EDTA as a chelating agent for alleviation of toxicity during leaching of lowgrade sulfide ores by this bacterium is highly beneficial.