THE RELATIONSHIP BETWEEN MICROBIAL METABOLIC-ACTIVITY AND BIOCORROSION OF CARBON-STEEL

The effect of metabolic activity (expressed by generation time, rate o f H2S production and the activity of hydrogenase and adenosine phospho sulphate (APS)-reductase enzymes) of the 8 wild strains of Desulfovibr io desulfuricans and of their resistance to metal ions (Hg2+, Cu2+, Mn 2+, Zn2+, Ni2+, Cr3+) On the rate of corrosion of carbon steel was stu died. The medium containing lactate as the carbon source and sulphate as the electron acceptor was used for bacterial metabolic activity exa mination and in corrosive assays. Bacterial growth inhibition by metal ions was investigated in the sulphate-free medium. The rate of H2S pr oduction was approximately directly proportional to the specific activ ities of the Investigated enzymes. These activities were inversely pro portional to the generation time. The rate of microbiologically induce d corrosion (MIG) of carbon steel was directly proportional to bacteri al resistance to metal ions (correlation coefficient r = 0.95). The co rrelation between the MIC rate and the activity of enzymes tested, alt hough weaker, was also observed (r = 0.41 for APS-reductase; r = 0.69 for hydrogenase; critical value r(c) = 0.30, p = 0.05, n = 40).