Studies on the application of microbially produced polymeric substances as protecting layers against microbially influenced corrosion of iron and steel

摘要

The contribution of biofilms to corrosion of metals and alloys, termed microbially influenced corrosion (MIC), is still a challenge for research in the field of corrosion protection. In order to inhibit or prevent MIC, one promising route can be to inhibit the adhesion of single cells. The processes of adhesion and desorption of microorganisms are known to be induced and mediated by various (bio-)molecules. The aim of this project is to identify and to investigate substances appropriate to inhibit the formation of biofilms of sulphate reducing bacteria (SRB). For this purpose, so-called extracellular polymeric substances (EPS) of various bacteria have been harvested from biofilms and purified. These substances have been analyzed with focus on chemical groups like proteins, carbohydrates or glucuronic acids. The EPS have been adsorbed on metal substrates in order to form layers probably protecting against adhesion of Desulfovibrio vulgaris. Layer formation and adhesion of bacteria were studied by epi-fluorescence microscopy (EFM) and atomic force microscopy (AFM). It was observed that the number of attached cells was significantly lower on the covered surfaces when compared to pure substrates. Additionally, most of the EPS were found to be resistant against degradation by Desulfovibrio vulgaris.