How to Cite
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that causes nosocomial infections in part due to its ability to colonize many biotic and abiotic surfaces. These persistent infections are difficult to treat due to a large repertoire of virulence factors, and the ability of the organism to form biofilms. It has previously been observed that biofilm formation in several bacterial species can be attenuated by the addition of salicylic acid (SA), through an unknown mechanism. As cell motility of twitching, swimming, and swarming are proven instrumental in biofilm formation, we investigated whether or not salicylic acid affected the motility of Pseudomonas aeruginosa. Motility assays conducted on wild-type strains (PAO1, PA14), flagella (PAO1 fliC, PA14 fliC ) and type IV pili (PAO1 pilB, PA14 pilB ) mutants, showed that sub-inhibitory concentrations of 25 and 50 mM salicylic acid significantly decreased bacterial swarming motility. These findings correlated with significant decrease in biofilm formation when incubated with salicylic acid (SA) concentrations of 10mM and higher. Since bacterial motility necessary for proper biofilm formation was impaired in a concentration-dependent manner, these data suggest that the suppressive effect of salicylic acid on flagella-related motility led to the previously observed reductions in biofilm formation. Twitching and swimming motility showed less inhibitory results than swarming motility, due to a lack of consistent replicates across three biological repeats. Twitching motility assays showed significant decreases at 50mM SA and swimming motility assays showed significant decreases at 25 and 50 mM SA for all strains tested except for PAO1 pilB. However, further studies are needed to confirm the effect and mode of action of salicylic acid on flagella and type IV pili gene expression or functionality.