Copper Stress Targets the Rcs System To Induce Multiaggregative Behavior in a Copper-Sensitive <i>Salmonella</i> Strain

ABSTRACT Salmonella Δ cuiD strains form mucoid colonies on copper-containing solid media. We show here that this multiaggregative behavior is caused by the Rcs-dependent induction of colanic acid extracellular polysaccharide. Deletion of cps operon genes in a Δ cuiD strain increased the sensitivity to copper, indicating a role for colanic acid in copper resistance.