Influence of copper-alloying of austenitic stainless steel on multi-species biofilm development

Aims: To investigate the bactericidal influence of copper-alloying of stainless steel on microbial colonization. Methods and Results: Inhibition of bacterial adherence was investigated by monitoring (192 h) the development of a multi-species biofilm on Cu-alloyed (3.72 wt%) stainless steel in a natural surface water. During the first 120 h of exposure, lower numbers of viable bacteria in the water in contact with copper-containing steel relative to ordinary stainless steel were observed. Moreover, during the first 48 h of exposure, lower colony counts were found in the biofilm adhering to the Cu-alloyed steel. No lower colony or viable counts were found throughout the remainder of the experimental period. Conclusions: The presence of Cu in the steel matrix impedes the adhesion of micro-organisms during an initial period (48 h), while this bactericidal effect disappears after longer incubation periods. Significance and Impact of the Study: The application of Cu-alloyed stainless steels for bactericidal purposes should be restricted to regularly-cleaned surfaces.