Metabolic state and catalase activity of P. fluorescens biofilms as related to corrosion of copper

DUVILE, FRANCISCO BERNARDO; NERCESSIAN, DÉBORA; BUSALMEN, JUAN PABLO

Rosario, Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2006

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

Aiming to determine reciprocal interactions at the biofilm/metal interface, biofilms of P. fluorescens (ATCC 17552) were biochemically analysed during the growth on copper, while electrochemical reduction curves were performed to evaluate the formation of the protective oxide layer on the metal. DNA profiles showed an extended lag phase for biofilms grown on copper as compared to those grown on glass. As indicated by the RNA/DNA ratio, the overall metabolic state of copper biofilms was always lower than that of glass biofilms. Also lower was catalase specific activity. When analysed by Western blot hibridization, the expression of at least four catalase isoforms were detected in P. fluorescens biofilms, with PM’s of 77, 63, 50 and 38.4 kDa.   The two lower bands being differentially expressed during growth on copper. The growth of the protective oxide layer of copper was inhibited by the presence of biofilms. Moreover, the existing oxide layer was decreasing with biofilms growth evidencing a biological effect on metal stability. Open biofilm with elevated cell clusters were observed at the reflectance microscope, which are presumed to allow the access of dissolved oxygen to the metal surface. Presented results reinforce the possibility for the action of the catalase mediated mechanism proposed previously as an explanation for microbiologically influenced corrosion.