Xanthan synthesized by strains of Xanthomonas campestris pv pruni: production, viscosity and chemical composition

Abstract

The aim of this work was to characterize the xanthan produced by 30 strains of the Xanthomonas campestris pv pruni, evaluating the production, viscosity and chemical composition. The xanthan production by each strain was evaluated through weight of the dry product for volume of broth fermented (g.l-1); the viscosity of 3 % (w/v) aqueous solutions of the biopolymers was measured in rheometer rotating mode at 25 ºC and the chemical composition was determined by comparative thin-layer chromatography (TLC). The xanthan production was strain dependent and the highest production reached 9.2 g.l-1 for strain 83 and the lowest 3.8 g.l-1 for strain 51. Strain 107 did not produce xanthan. The aqueous solutions of the xanthans produced showed pseudoplastic behavior. The xanthan synthesized by strain 101 showed the highest viscosity and strain 83 produced the xanthan with the lowest viscosity. All the xanthans synthesized contained glucose, rhamnose, mannose and glucuronic acid in their chemical composition, differently from commercial xanthan, that do not contain rhamnose. There was not relation between yield, viscosity and chemical composition. The yield obtained was not the one recognized by literature as appropriate for industrial production, but the viscosity of the aqueous solutions of the xanthans synthesized by sixteen strains was higher than the commercial xanthan, compensating for the low production.