Retardation of biofilm formation with reduced productivity of alginate as a result of Pseudomonas aeruginosa exposure to Matricaria chamomilla essential oil

Bacterial adhesion to solid surfaces and biofilm development are ubiquitous phenomena with several deleterious medical and economic consequences. The establishment of biofilms by alginate-producing P. aeruginosa strains is the most common mode of growth in cystic fibrosis patients with chronic lung infections, with the biofilms providing a protected environment against the host immune system and a number of antibiotics. Selected natural products that originate in plants can influence microbial biofilm formation. In this paper specific inhibition of alginate production by and antibiofilm activity of Matricaria chamomilla essential oil against Pseudomonas aeruginosa are studied. Disk diffusion method employed to evaluate P. aeruginosa inhibition exposed to the essential oil concentrations of Matricaria chamomilla L. did not show antimicrobial property. The oil composition analyzed by GC and GC/MS led to identification of 18 components of which the major ones were: guaiazulene (25.6%), (E)-β-faransens (20.1%), chamazulene (12.4%), α-bisabolol oxide B (7.3%), α-bisabolol (7.3%), and hexadecanole (5.6%). Biofilm formation was studied using saffranin stain employing plate reader. Alginate production was quantified in absence and in presence of the essential oil concentrations. The alginate production reduced significantly as the oil concentration increased. At the oil concentration of 0.5 µg/ml both biofilm and alginate reduced restoring alginate/biofilm ratio to normal level with decreased biofilm/alginate ratio. Use of natural agents capable of reducing biofilm formation would be useful in control of microbial pathogenicity leading to the prevention of infections of numerous biofilm producing bacterial species.