the effect of essential oil of matricaria chamomillal. on biofilm formation of pseudomonas aeruginosa

background and objectives: pseudomonas aeruginosais an important opportunistic pathogen. the mucoid strains of p. aeruginosa produce hyper viscous substances consisting mainly of alginate which have important roles in formation of biofilm.we investigated the effect of essential oil of matricaria chamomilla l. on biofilm production in p. aeruginosa. material and methods: p. aeruginosa 8821m was used as standard strain for biofilm production. antibacterial effects of essential oil of m. chamomilla l. (50% in dmso) was tested by disk diffusion method. the effect of essential oil on biofilm formation of p. aeruginosa 8821m was evaluated following inoculation of bacteria in lb broth medium containing 0.5, 0.35 and 0.2 µg/ml of oil which were incubated for 24h at 37°c. the biofilm formation was measured by fonseca method. bacteria inoculated and uninoculated media without oil were used as positive and negative controls, respectively. results: the results showed that the essential oil did not have any antibacterial effect or reduction in biofilm formation in the presence of 0.35 and 0.2 µg/ml of oil. on the other hand, bacteria biofilm formationwas significantly reduced in the presence of 0.5µg/ml of oil in comparison with positive control. conclusion: this research showed that the essential oil of matricaria chamomilla l. had no antibacterial effect, but caused reduced biofilm formation in p. aeruginosa. biofilm formation is an important virulence factor in mucoid strains and our results may suggest the possible use of essential oil in control of infections caused by p. aeruginosa or other related infections