FIG 3.

Biofilm formation in dynamic milk flow by S. thermophilus UC8547 (○), its spontaneous mutant UC8547Δ3 (△), and the prtS-null mutant UC8547Δ16 (□) over 36 h. Planktonic cells (white symbols and dotted line) are expressed as CFU per milliliter, while sessile cells (gray symbols and continuous line) are expressed as CFU per square centimeter. The reported data are the averages of the results from three independent experiments. Standard deviations are indicated by bars. No significant differences were observed in the planktonic cells counts between the three isogenic strains. The numbers of sessile cells adhered to stainless steel indicate that UC8547Δ3 and UC8547Δ16 have impaired biofilm formation. Values with different letters are significantly different (P < 0.05, one-way ANOVA).