Emulsifying properties of a glycoprotein extract produced by a marine Flexibacter species strain TG382

We report, for the first time, on the production of an emulsifying polymer produced by a Flexibacter species (designated strain TG382). This polymer, E-382, was produced extracellularly during growth of the organism in a marine broth amended with glucose. After cold ethanol precipitation, extensive dialysis and lyophilization, a chemical analysis of the resultant dried polymer revealed it to be a glycoprotein composed of 10.9% protein, 23.3% carbohydrate and a 5.5% uronic acid content. At relatively low concentrations (0.02%, w/v), E-382 was found to form oil-in-water emulsions against hydrocarbon and food oils under neutral pH and acidic conditions. The most stable emulsions were formed against the oils sunflower, vegetable and ground nut under neutral pH conditions. Aqueous solutions of the polymer were viscous, and its reduced viscosity (ηred) was determined to be 0.54 m3/kg. Although proteins and uronic acids may possess surface-active properties, the viscosifying effect of this polymer, which is a typical feature of some commercial hydrocolloids, is more likely to confer its high emulsion-stabilizing qualities.