Effect of escherichia coli K12 adhesion and biofilm growth on the surface chemical composition of 70Cu-30Ni alloy, 304L stainless steel and titanium

摘要

Copper alloys, stainless steel and titanium are used in industrial plants and can be affected by biocorrosion induced by biofilm formation. Modifications of the passive film after Escherichia coliK-12 adhesion in the early stage of biofilm formation were investigated by XPS (X-ray Photoelectron Spectroscopy) in order to determine the effect of its influence on the surface chemical composition of 70Cu-30Ni, 304L stainless steel and titanium. Qualitative and quantitative analysis of the elements in the passive film, and the analysis of the deposited organic layer, were done by XPS. Two kind of experiments were performed: adhesion for 1 hour and biofilm growth for 24 hours of exposure to the bacteria, and their respective abiotic controls. Epifluorescence evidenced the differences of bacterial adhesion performance. After 1 hour of adhesion, the number of adhering bacteria for CuNi was lower than for stainless steel and titanium samples. After 24 hours of adhesion, the number of adhering cells decreased slightly for CuNi and on the contrary increased for stainless steel and titanium samples. Surface analyses showed an enrichment in Cu (Cu~(2+)) of the oxide film of CuNi samples and a Cr enrichment of the stainless steel passive film after 24 hours of exposure. No modification of the oxide layer was observed on Ti samples.