Figure 3. Biofilm formation by ΔphoPR and ΔdltABCD L. monocytogenes.

Bacterial strains were inoculated into TSBYE media in 96-well plates and grown at 35°C for 24 hours. Cultures were then diluted 1:10 into fresh HTM media with 3% glucose and 0.1 mg/mL each cysteine and methionine in new 96-well PVC microtiter plates. Plates were incubated at 35°C for 96 hours, rinsed with dH₂O using a semi-automated cell washer, stained with crystal violet, rinsed with acetic acid and the OD₅₉₅ ±SD determined using a spectrophotometer. The data presented are representative of three independent experiments. *, p <0.05 (One-way ANOVA test).