Figure 4

Changes of bacterial bioluminescence on copper and copper alloy surfaces. Results on Cu-induced E. coli (pSLcueR/pDNPcopAlux) (a,c,e) and on constitutively bioluminescent E. coli (b,d,f). Bioluminescence in relative light units (a,b) and fold change (c,d) when exposed to copper surfaces: C11000 (99.9% Cu), C51000 (94.2% Cu, 5.8% Sn), C70600 (89% Cu, 10% Zn), C26000 (69–72% Cu, 28–31% Zn), C71500 (64–69% Cu, 29–33% Ni), C75200 (63–67% Cu, 13–20% Zn,17–20% Ni), C28000 (59–63% Cu, 37–41% Zn) during 60 min in LB medium. Solid red line indicates background (non-exposed) bioluminescence and dotted red line significantly increased (Cu biosensor) or decreased (constitutively bioluminescent E. coli). (e,f) Viable bacterial counts on copper surfaces after 60 min exposure compared to control (PE) surface. Significant differences in viable counts from control value based one-way analysis of variance (ANOVA) and Dunnett’s multiple comparisons test are marked p < 0.1(.); p < 0.05(*); p < 0.01(**); p < 0.001(***); p < 0.0001(****).