IIB   20738
INSTITUTO DE INVESTIGACIONES BIOLOGICAS
Unidad Ejecutora - UE
artículos
Título:
Metabolic turnover and catalase activity of biofilms of P. fluorescens (ATCC 17552) as related to copper corrosion
Autor/es:
DÉBORA NERCESSIAN; FRANCISCO B. DUVILLE; MARIELA DESIMONE; SILVIA SIMISON; JUAN PABLO BUSALMEN
Revista:
WATER RESEARCH
Editorial:
Elsevier B.V.
Referencias:
Año: 2010 vol. 44 p. 2592 - 2600
ISSN:
0043-1354
Resumen:
In this work we report the results of a combined biochemical and electrochemical studyaimed to analyze both the growth of biofilms of Pseudomonas fluorescens on copper samplesand its possible role in the instability of the metal/electrolyte interface.DNA and RNA were quantified along the time for biofilms grown on copper and glass toestimate both the growth of the bacterial population and its metabolic state (through theRNA/DNA ratio). The expression and specific activity of catalase were also determined togain insight into their possible role in corrosion acceleration. The electrochemical behaviorof the biofilm/copper interface was monitored by Linear Polarization Resistance (Rp) andelectrochemical impedance spectroscopy (EIS) along the experiments.Results showed a longer lag phase for biofilms developing on copper that included a periodof high metabolic activity (as measured by the RNA/DNA ratio) without biomass growth.Biological activity introduced a new time constant at intermediate frequencies in EISspectra whose capacitive behavior increased with the biofilm development. The incrementin this biofilm-related signal was accompanied by a strong limitation to charge transferthrough a diffusion controlled process probably due to oxygen exhaustion by cells respiration,while the resistance of the interface decreased presumably due to oxide dissolutionby local acidification under the colonies. In addition, catalase activity was found to be highin mature copper-tolerant biofilms, which differentially express a catalase isoform notpresent in biofilms growing on glass.