Effect of exopolysaccharides oxidation and metabolic inhibition on the adhesion and biofilm formation by marine Pseudomonas sp.

Biofilm is a microbially derived sessile community, attached to an interface, embedded in gelatinous matrix. Biofilm exhibits an altered phenotype with respect to growth, gene expression, and protein production. Attachment of microorganisms is the first step in biofilm formation on any surface.

According to DLVO theory, the net force of interaction between a bacterial cell and a surface arises from the balance between van der waals forces of attraction and electrostatic double layer forces of repulsion. These repulsive barriers are bridged by exopolymers, specially exopolysaccharides, that promotes irreversible attachment of bacterial cells to surfaces.

Exopolymeric substances are suggested to perform many functions in biofilm. However, maintenance and protection of biofilm are some of the most important functions of exopolymers. Furthermore, the presence of exopolymeric substances affects the cell surface properties, which significantly affects regulation of surface attachment, biofilm maturation and ultimately biofilm detachment.

To determine the role of exopolysaccharides in initial adhesion and biofilm formation we studied the effect of, carbohydrate oxidation by sodium- m- periodate, and the inhibition of exopolysaccharides synthesis by 2,4-dinitrophenol on the adhesion of marine Pseudomonas. sp to polystyrene panels in vitro . Sodium periodate treatment resulted in only 35% reduction in the adhesion of Pseudomonas sp to polystyrene. This implies that some other compounds or sodium periodate resistant exopolysaccharides were perhaps involved during adhesion of Pseudomonas sp to polystyrene. Furthermore, adherence could not be blocked by 0.05 mM 2,4 dinitrophenol treatment significantly. This also suggests that inhibition of carbohydrate synthesis at oxidative phosphorelyation level had no effect on bacterial adhesion .0ur results suggest that oxidation of carbohydrates and inhibition of carbohydrate production had little effect on the adhesion of bacterium to the surface. This means that there is a possibility of involvement of other components, not influenced by these two commonly proposed treatments to explain the mechanisms of adhesion.

From- http://www.nio.org/; Anand Jain and N.B.Bhosle, Marine Corrosion and Material Research Division, National Institute of oceanography, India