AsrR Is an Oxidative Stress Sensing Regulator Modulating Enterococcus faecium Opportunistic Traits, Antimicrobial Resistance, and Pathogenicity
Figure 7
AsrR is involved in biofilm formation and adhesion to eukaryotic cells.
(A) Direct observation of biofilm formation on polystyrene by the parental (HM1070), mutant (ΔasrR), and complemented (ΔasrR::asrR) strains, after a crystal-violet staining. (B) Ability of the strains to form biofilm on a polystyrene surface is shown after 24 h of incubation at 37°C. Values, measured with a microplate reader, are from three independent experiments performed in triplicate. Median and interquartile range values are shown. Note that the ΔasrR strain produced biofilm whereas parental and complemented strains did not produce biofilms under the tested conditions. (C) Adhesion of the strains to HT-29 cells. Adherence level is expressed as the percentage of adherent enterococci relative to the inoculum count. Values are from three independent experiments performed in triplicate. Median and interquartile range values are shown. The ΔasrR strain was found to be more adherent to epithelial HT-29 cells compared to parental and complemented strains.