Effects of chlorogenic acid on biofilm formation of Pseudomonas aeruginosa with different levels of cyclic diguanosine

Objective: To study the inhibitory effects of chlorogenic acid on the early and mature biofilm (BF) of Pseudomonas aeruginosa (P.a) at different levels of cyclic diguanosine (c-di-GMP).Methods: The minimum inhibitory concentration (MIC) was determined by liquid medium dilution method.BF models of three P.a strains-PAO1, P.a strain with high expression of intracellular c-di-GMP (PaO1ΔwspF) and P.a strain with low expression of intracellular c-di-GMP (PAO1/P_lac-yhjH) were constructed in vitro and the models were divided into blank control group and chlorogenic acid (1/2 MIC, 1/4 MIC, 1/8 MIC) group with different concentrations.The total amount of BF on the carrier surface of 3 d and 7 d was determined by semi-quantitative crystal violet staining, and the viable bacteria in BF after 3 and 7 days of chlorogenic acid treatment were counted by continuous dilution method to observe the effects of chlorogenic acid on exercise ability.Results: Under the action of chlorogenic acid, the BF formed on the carrier surface of both 3d and 7d was less than that of the blank control group (P＜ 0.05), the number of viable bacteria in BF was less than that of the blank control group (P＜ 0.05), and the diameter of the moving area of the three strains was smaller than that of the blank control group (P＜ 0.05).Conclusion: Chlorogenic acid can inhibit early and mature BF of P.a at different levels of c-di-GMP and has a good killing effect on BF live bacteria, affecting their exercise ability.