Glycoprotein emulsifiers from two marine Halomonas species: chemical and physical characterisation

Aims: To partially purify and characterize bioemulsifiers produced by two new marine Halomonas species, TG39 and TG67, and to compare their emulsifying activities with those of commercial emulsifiers. Methods and Results: The production of emulsifiers HE39 and HE67 was achieved from glucose-supplemented marine broth, and recovered by cell removal, concentration by ultrafiltration, precipitation with salt and ethanol, and lyophilization. Purification and chemical analysis revealed both emulsifiers to be glycoproteins of high molecular weight with a notably high content of protein and uronic acids. Physical characterization showed both glycoproteins to effectively emulsify a wide range of food oils under both neutral and acidic pH conditions and withstand acid and high temperature treatment. Conclusions: The emulsifying activities of these two new glycoprotein emulsifiers were comparable and, under certain conditions, superior to those produced by commercial emulsifiers tested (xanthan gum, gum arabic and lecithin). They show the highest reported emulsifying activities derived from a Halomonas species. Significance and Impact of the Study: These strains, and the emulsifiers produced, appear to be promising candidates for further development in applications requiring emulsifiers that are natural and compatible to the existing commercial emulsifiers.