Microbial exopolysaccharides: Effect on corrosion and partial chemical characterization



Test panels of mild steel were deployed in the surface waters of the Dona Paula Bay over a period of 28 days. Biofilm material on mild steel panels was analyzed for biofilm biomass (as organic carbon), exopolysacchande (EPS) production and corrosion rates. Concentrations of biofilm carbon and BPS increased whereas corrosion rate of mild steel decreased over the period of immersion Corrosion of mild steel showed significant inverse relationships with biofilm carbon and BPS. This implies that biofilm organic matter inhibits the corrosion of mild steel. A few bacterial cultures isolated from the microfouling material were screened for EPS production. One of the cultures identlfied as vibrio sp produced the highest amount of exopolysaccharides. Production, isolation and charactenzation of the exopolysaccharides produced by the bactenum were evaluated. Exopolysaccharide was produced in all the phases of growth and with all the substrates tested. Production of the exopolysnccharide was influenced by source and concentration of carbon and nitrogen as well as concentration of phosphate in the growth medium. Ex:opolysacchacide is a heteropolysaccharide- containing glucose as the most abundant monosaccharide and mannose, xylose. galactose and fucose as minor sugars. The presence of uronic acid and pyruvate indicates the acidic nature of the polysacchande.


Mild steel; corrosion; microorganisms; exopolysaccharides.

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