Resumen:
he present study was designed to determine the relationships among biofilm formation, cellular stress and release of Shiga toxin
(Stx) by three different clinical Shiga toxin-producing Escherichia coli (STEC) strains. The biofilm formation was determined using
crystal violet stain in tryptic soy broth or thioglycollate medium with the addition of sugars (glucose or mannose) or hydrogen
peroxide. The reactive oxygen species (ROSs) were detected by the reduction of nitro blue tetrazolium and reactive nitrogen
intermediates (RNI) determined by the Griess assay. In addition, the activities of two antioxidant enzymes, superoxide dismutase
(SOD) and catalase (CAT), were studied. For the cytotoxicity studies, Vero cells were cultured with Stx released of STEC biofilms.
The addition of sugars in both culture mediums resulted in an increase in biofilm biomass, with a decrease in ROS and RNI
production, low levels of SOD and CAT activity, and minimal cytotoxic effects. However, under str