Figure 9

Agr system plays a role in biofilm development induced by nicotine. (A) The relative mRNA expression of Agr system genes (agrA, agrB, agrC, and agrD) was evaluated at 2 h and 24 h during the biofilm formation process in the presence or absence of nicotine. (B) The relative mRNA expression of agrA, agrB, agrC, and agrD genes were detected when treated with 0, 1 mg/ml, 2 mg/ml nicotine at 24 h. (C) The number of attached bacteria was counted and analyzed in USA300, USA300-agrA, USA300-agrC. The nicotine-induced enhancement of the initial attachment stage was abolished in these two mutant strains. Data were represented as mean ± SD of three independent experiments. *P < 0.05.