FIG 6.

S. aureus icaA and cidA gene expressions versus adhesion forces in 24-h-old biofilms. (A and C) Normalized icaA expression in 24-h-old S. aureus ATCC 12600 (A) and S. aureus ATCC 12600 Δpbp4 (C) biofilms as a function of the adhesion force. (B and D) Normalized cidA expression in 24-h-old S. aureus ATCC 12600 (B) and S. aureus ATCC 12600 Δpbp4 (D) biofilms as a function of the adhesion force. Linear regression analysis was performed for all graphs to analyze the correlation between gene expression and adhesion force. The solid lines represent the best fit to a linear function, while r² values represent the correlation coefficients. The dotted lines enclose the 95% confidence intervals. The levels of icaA and cidA expression were normalized to the level of gyrB expression and are presented as normalized fold expression with respect to the results for PE. Each point represents the average ± standard error of the mean from three individual experiments with separately grown staphylococcal cultures.