Fig 1.

Biofilm formation (A₅₇₅) on PS microplates by the 11 L. monocytogenes strains (A) and the 8 S. enterica strains (B). Biofilm cells were indirectly quantified by crystal violet staining and absorbance measurements at 575 nm. Monoculture biofilms were left to be formed on PS microplates for 48 h under four different environmental conditions: at 15°C in TSB (□), at 15°C in dTSB (■), at 30°C in TSB (▧), and at 30°C in dTSB (▤). In all cases, growth medium was renewed at 24 h of incubation. The bars represent the mean values ± standard deviations (n = 8, two independent experiments, each performed four times). For each figure separately, mean values sharing at least one common lowercase letter shown above the bars are not significantly different at a P value of <0.05. Strains selected for biofilm formation on SS coupons are included in dashed rectangular boxes.