Effect of copper upon the actions of sulphate-reducing bacteria isolated from soil contaminated by crude oil and heavy metals / Wpływ miedzi na aktywność bakterii redukujących siarczany wyizolowanych z gleby zanieczyszczonej ropą naftową i metalami ciężkimi

In the present study, copper tolerance by a mixed culture of sulphate-reducing bacteria (SRB) were evaluated. These sulphidogenic microbial communities were isolated from soils polluted by crude oil, oil-derived products and heavy metals (from selected areas of crude oil mines in south-eastern Poland).

Copper tolerance of SRB was tested in modified Postgate C medium with ethanol and lactate as the sole carbon source and copper chloride at concentrations ranging from 0 to 1500 mg/l. Bacterial growth and sulphate reduction were possible between 100 and 1500 mg/l of initial copper concentration. Active sulphate reduction - maximum of 53% was observed in the cultures.

Molecular analysis indicated not only the presence of SRB but also other microorganisms that are capable of living in environments contaminated by heavy metals. The high environmental sulphide concentrations produced by SRB lead to the precipitation of any biogenic mineral phases such as metal sulphides. As a result, soluble metal ion concentrations in the microenvironment of SRB are, therefore, extremely low. This process allows SRB to grow in environments containing high levels of toxic metals. Studies on SRB tolerance to heavy metals are extremely important because of the possibility of using this group of microorganisms for the bioremediation and microbial revitalisation of areas contaminated by heavy metals.