Effects of Citrus limon (L.) essential oil on Pseudomonas aeruginosa: complemented with a computational approach; focus on quorum sensing

Antibiotic-resistance is becoming an increasingly important concern. Resistant bacteria like Pseudomonas aeruginosa have different strategies while encountering either the immune system or antibiotics. As an example biofilm formation or quorum sensing can be mentioned as bacterial mechanisms to gain resistance. Therefore, it is crucial to explore novel compounds that might disrupt biofilm production especially using organic and plant-based compounds. Citrus limon essential oil has been used against multiple types of microorganisms in traditional medicine. The purpose of this study is to investigate the effect of this essential oil on P. aeruginosa biofilm formation. The inhibition of biofilm was measured using a micro-dilution method, staining the biofilm that has been formed and determining the minimum inhibitory concentration that proved effective. Then, via molecular docking software, the ligands more likely to interact with biofilm proteins were predicted. Our results suggest that after multiple determinations of minimum inhibitory concentration, the lowest effective dose was in concentrations between 100 μg/ml to around 450 μg/ml. Furthermore, molecular docking results demonstrated that between all the essential oil ligands, the top three were geranyl acetate, α-terpineol, and β-bisabolene. To sum up, Citrus limon essential oil showed promising anti-quorum sensing properties and it can be considered as a source of antimicrobial formulation.