The antifouling potentiality of galactosamine characterized from Vibrio vulnificus exopolysaccharide

To gain a better insight into biofilm composition, the exopolysaccharide (EPS) of the Gram-negative bacterium Vibrio vulnificus was studied. Monosaccharide composition analysis of the wild-type and mutant V. vulnificus EPS carried out with Bio-liquid chromatography revealed the presence of D-glucosamine, D-galactose, D-glucose and D-xylose in both strains. D-Galactosamine was found only in the mutant that formed less biofilm compared to its wild-type. The influence of galactosamine on biofilm formation was then studied by adding this substance gradually to six different Gram-negative/positive bacteria associated with various autoinducers. Four bacterial species known to use the autoinducer type-2 signaling system produced less biofilm in the presence of galactosamine. No significant inhibition of biofilm formation was observed in bacteria that produce autoinducer type-1 signal molecules. Galactosamine was also immobilized on polymeric nanofibers to determine its re-usability for the study of biofilm inhibition. The immobilized galactosamine retained >65% of its initial antifouling activity after 10 repeated uses. The results of this study suggest the antifouling role of galactosamine for bacteria that produce AI-2.