Effects of various physicochemical parameters on the Biofilm formation and Pyocyanin production in Pseudomonas aeruginosa PA14.

Background: Biofilm formation in Pseudomonas aeruginosa provides protection against multiple stressors and contributes to its pathogenicity. Pyocyanin, a virulence factor regulated by quorum sensing, is crucial for infections. This study aimed to evaluate how various physicochemical conditions impact biofilm formation and pyocyanin production in P. aeruginosa PA14.

Methods: Biofilm formation and pyocyanin production were assessed under varying conditions, including nutrient availability, NaCl concentrations, pH, temperature, heavy metal salts, light exposure, and microbial competition. Biofilm levels were quantified using a crystal violet assay, while pyocyanin levels were measured spectrophotometrically. Statistical analyses were performed to identify significant trends and correlations.

Results: Key findings revealed that biofilm formation and pyocyanin production were reduced under most stress conditions examined in this study, compared to controls, with few exceptions. FeCl₃ enhanced biofilm formation, while NaCl concentrations above 3% and extreme pH values inhibited it. NiCl₂ was the most effective at reducing biofilm amount among the salts which we examined. Pyocyanin production followed similar trends, peaking under neutral pH and nutrient-enriched conditions. Positive correlations between biofilm and pyocyanin production were observed, particularly in nutrient-limited media. Additionally, light exposure and inter-microbial competition significantly reduced biofilm levels.

Conclusion: This study highlights the differential responses of P. aeruginosa to various stress conditions, underscoring the importance of environmental factors in modulating biofilm formation and virulence. These findings provide insights into bacterial adaptive strategies and offer potential avenues for developing targeted interventions against biofilm-associated infections.