Introduction. Escherichia coli O157:H7 possesses one chromosomal and two prophagic
sodC genes encoding for Cu,Zn superoxide dismutases. We evaluated the contribution of
sodC genes in biofilm formation and its resistance to hydrogen peroxide.
Methods. The biofilm of sodC deletion mutants has been studied, in presence or absence
of hydrogen peroxide, by crystal violet in 96-well plates and Scanning Electron Microscopy
on glass coverslips.
Results. Deletion of prophagic sodC genes had no effect on biofilm construction, in contrast
to the chromosomal gene deletion. Hydrogen peroxide treatment showed higher
cell mortality and morphological alterations in sodC deletion mutants respect to wild
type. These effects were related to the biofilm development stage.
Conclusion. The role of the three SodCs is not redundant in biofilm formation and the
resistance to oxidative damage. The stage of biofilm development is a crucial factor for
an effective sanitization.