Fig. S1. Cellulose production by the spontaneous non-rdar mutants. Overnight LB cultures were streaked onto agar (1.5%) prepared without NaCl and supplemented after autoclaving with Calcofluor white/Evans blue solution (Sigma Aldrich) at 40 μg ml−1. Plates were incubated at room temperature in the dark for 48 h, and then imaged on UV trans-illuminator, as in Da Re and Ghigo (2006). Plates on the UV trans-illuminator table were photographed with a digital camera. To quantify fluorescence, cells were washed off plates with sterile distilled water; OD600 and fluorescence (ex. 360 ± 40 nm; em. 460 ± 40 nm) were measured with a microtitre plate reader. Numbers at the bottom of each panel represent relative fluorescence (expressed as fluorescence per unit of OD600). Averages of three independent cultures are shown plus/minus standard error.


Fig. S2. The effect of rpoS S.Typhimurium 14028 on the non-rdar phenotypes of the Salmonella isolates. pWZ1 (a pWSK29 carrying a copy of rpoS amplified from S. Typhimurium 14028) was electroporated into each of the isolates of interest; pWSK29 vector was similarly electroporated as a control. Isolates of sv. Newport are from a tomato field on the Eastern Shore of Virginia (where outbreaks of salmonellosis are known to have originated), isolate of sv. Montevideo LJH519 is from a tomato outbreak. All three isolates of sv. Braenderup were isolated from a single outbreak of salmonellosis linked to the consumption of tomatoes, although each strain came from a different patient at the different points in the outbreak.


Table S1. Strains and plasmids used in this study.


Table S2. Primers used in this study.


Table S3. Appearance of Salmonella isolates on Congo red-containing plates.


Appendix S1. Materials and methods.

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