Antibiofilm Activity of Antarctic Sponge-Associated Bacteria against Pseudomonas aeruginosa and Staphylococcus aureus

Bioprospecting in unusual marine environments provides an innovative approach tosearch novel biomolecules with antibiofilm activity. Antarctic sponge-associated bacteriabelonging to Colwellia, Pseudoalteromonas, Shewanella and Winogradskyella genera were evaluated fortheir ability to contrast the biofilm formation by Pseudomonas aeruginosa ATCC 27853 andStaphylococcus aureus ATCC 29213, as model organisms. All strains were able to produce biofilm atboth 4 and 25 °C, with the highest production being for Colwellia, Shewanella and Winogradskyellastrains at 4 °C after 24 h. Antibiofilm activity of cell-free supernatants (CFSs) differed amongstrains and on the basis of their incubation temperature (CFSs4°C and CFSs25°C). The major activitywas observed by CFSs4°C against S. aureus and CFSs25°C against P. aeruginosa, without demonstratinga bactericidal effect on their growth. Furthermore, the antibiofilm activity of crude extracts fromColwellia sp. GW185, Shewanella sp. CAL606, and Winogradskyella sp. CAL396 was also evaluatedand visualized by confocal laser scanning microscopic images. Results based on the surface-coatingassay and surface tension measurements suggest that CFSs and the crude extracts may act asbiosurfactants inhibiting the first adhesion of P. aeruginosa and S. aureus. The CFSs and the novelbiopolymers may be useful in applicative perspectives for pharmaceutical and environmentalpurposes.