The Swarming Motility of Pseudomonas aeruginosa Is Blocked by Cranberry Proanthocyanidins and Other Tannin-Containing Materials

Abstract

Bacterial motility plays a key role in the colonization of surfaces by bacteria and the subsequent formation of resistant communities of bacteria called biofilms. Derivatives of cranberry fruit, predominantly condensed tannins called proanthocyanidins (PACs) have been reported to interfere with bacterial adhesion, but the effects of PACs and other tannins on bacterial motilities remain largely unknown. In this study, we investigated whether cranberry PAC (CPAC) and the hydrolyzable tannin in pomegranate (PG; punicalagin) affected the levels of motilities exhibited by the bacterium Pseudomonas aeruginosa. This bacterium utilizes flagellummediated swimming motility to approach a surface, attaches, and then further spreads via the surfaceassociated motilities designated swarming and twitching, mediated by multiple flagella and type IV pili, respectively. Under the conditions tested, both CPAC and PG completely blocked swarming motility but did not block swimming or twitching motilities. Other cranberry-containing materials and extracts of green tea (also rich in tannins) were also able to block or impair swarming motility. Moreover, swarming bacteria were repelled by filter paper discs impregnated with many tannin-containing materials. Growth experiments demonstrated that the majority of these compounds did not impair bacterial growth. When CPAC-or PGcontaining medium was supplemented with surfactant (rhamnolipid), swarming motility was partially restored, suggesting that the effective tannins are in part acting by a rhamnolipid-related mechanism. Further support for this theory was provided by demonstrating that the agar surrounding tannin-induced nonswarming bacteria was considerably less hydrophilic than the agar area surrounding swarming bacteria. This is the first study to show that natural compounds containing tannins are able to block P. aeruginosa swarming motility and that swarming bacteria are repelled by such compounds.

In vitroEffects of Anthocyanidins on Sinonasal Epithelial Nitric Oxide Production and Bacterial Physiology

“…Although a statistically significant reduction in S. aureus biofilm growth was seen with keracyanin, it is unclear whether this small decrease (Ͻ1 log) in vitro would result in clinically significant biofilm reduction in vivo. Cranberry proanthocyanidins, another flavonoid class, were previously shown to have antibiofilm properties 76 and block P. aeruginosa swarming, 77 which indicates that they may be more useful as therapeutics than anthocyanidins.…”

The Effect of Alkaloids, Saponinsand Thymoquinone of Nigella Sativa Seeds on Biofilm Production, Motility, Outer Membrane Proteins and Lipopolysaccharide of Some Bacteria.

“…In a previous study,tannins of cranberry fruit and the hydrolysable tannin in pomegranate were reported to inhibit swarming motility but did not block swimming or twitching motilities (51). Sub-inhibitory concentrations of alkaloids like piperine of black pepper and reserpine of snakeroot, decreased bacterial swarming and swimming motilities (52). Tannic acid and epigallocathecingallate were found to block swarming motility in Pseudomonas aeruginosa (53).…”

Antibacterial, anti-swarming and anti-biofilm formation activities of Chamaemelum nobile against Pseudomonas aeruginosa

“…The plate was pointinoculated with an overnight culture of PAO1 once the overlaid agar had solidifi ed, and incubated at 37°C for 3 days. The extent of swarming was determined by measuring the area of the colony (16) . The experiment was performed in triplicate and repeated twice.…”