Fig 1. The biofilm phenotypes of representative nontyphoidal and typhoidal Salmonella strains.

Salmonella strains that are known to cause gastroenteritis or enterocolitis (green), invasive disease (blue) or typhoid fever (red) were screened: for the ability to form the red, dry, and rough (rdar) morphotype, which presents as the formation of concentric rings and a wrinkled appearance on the surface of macrocolonies (panels 1 and 2, top); for the presence of multicellular, biofilm aggregates and planktonic cells in liquid cultures grown under biofilm-inducing conditions (middle panel; conical tubes); and for cellulose production, visualized as the white and fluorescent appearance of macrocolonies in the presence of calcofluor white dye (bottom panel).