Multiple environmental factors influence the importance of the phosphodiesterase DipA upon Pseudomonas aeruginosa swarming.

5 years ago

Multiple environmental factors influence the importance of the phosphodiesterase DipA upon Pseudomonas aeruginosa swarming.

Nachiket Kamatkar, Anne E Mattingly, Bradley R Borlee, Joshua D Shrout

Pseudomonas aeruginosa exhibits flagellar-mediated swimming in liquid and swarming on hydrated surfaces under diverse nutrient conditions. Prior studies have implicated a phosphodiesterase, DipA, in regulating these flagella-mediated motilities, but collectively, the necessity for DipA was unclear. In this study, we find that the media composition conditionally constrains the influence of DipA on flagellar motility. We show that DipA exhibits more influence on minimal media supplemented with glutamate or glucose where flagellar motility was negated for the dipA mutant. Conversely, a dipA deficient mutant exhibits flagellar motility when growing with Difco LB Lennox and minimal media supplemented with casamino acids. Swarming under these rich media conditions occurs under elevated levels of c-di-GMP. We also demonstrate that the influence of DipA upon swimming often differs from that upon swarming and we conclude that direct comparison of the motility phenotype is generally valid only when characterizing motility assay results from the same medium composition. Our results are consistent with an explanation that DipA is one of several phosphodiesterases responding to the nutrient environment sensed by P. aeruginosa On minimal medium with glutamate or glucose, DipA is dominant, however, on rich media, the necessity of DipA is fully negated.IMPORTANCE Motile and ubiquitous bacteria like Pseudomonas aeruginosa can quickly colonize surfaces and form biofilms in numerous environments such as water distribution systems, soil, and the human lung. To effectively disrupt bacterial colonization, it is imperative to understand how bacteria regulate motility in these different growth environments. Here we show that the phosphodiesterase DipA is not required for flagellar motility under all nutrient conditions. Thus, maintenance of intracellular c-di-GMP levels to promote flagellar motility or biofilm development must be conditionally regulated by differing phosphodiesterases in variation with select nutrient cues.

Publisher URL: http://doi.org/10.1128/AEM.02847-17

DOI: 10.1128/AEM.02847-17