Protection of Metal Surfaces from Microbial Colonization

This review discusses some aspects relating to the microbial interaction to metal surfaces. Most of the previous studies assumed that this process results in increased corrosion rates (MIC), however more recently it has been reported that many bacterial species can reduce corrosion rates of different metals and alloys in many corrosive environments by changing drastically the electrochemical conditions at the metal-solution interface. These changes ranged from acceleration of corrosion to corrosion inhibition. Microorganisms can contribute to corrosion inhibition by different means such as neutralizing the action of corrosive substances, formation of protective films on a metal surface and finally through the induction of a decrease in the medium corrosiveness. The mechanism of corrosion protection seems to be different for different bacteria since it has been found that the corrosion potential Ecorr became more negative in the presence of Shewanella ana and algae, but more positive in the presence of Bacillus subtilis. We previously described the efficient effect of the prepared 1,3-Bis-(4-amino-benzoyl) thiourea (AB-T) compound on corrosion inhibition of carbon steel in 0.5 M hydrochloric acid solution using different concentrations and different methods. In addition, results obtained indicated that AB-T was found to possess an anti-microbial activity against Gram-positive bacteria (Bacillus mycoides), Gram-negative bacteria (Escherichia coli) and non-filamentous fungi (Candida albicans).