Structural characterization and rheological properties of dextran produced by native strains isolated of Agave salmiana

The genus Leuconostoc belongs to a group of lactic acid bacteria usually isolated from fermented vegetables, which includes species involved in the production of exopolysaccharides (EPS) with commercial potential. This study was aimed to produce and characterize exopolysaccharides of four strains of Leuconostoc mesenteroides, which were isolated from aguamiel of Agave salmiana. The EPS were obtained with sucrose, pH 6, without agitation and incubation at 30 °C for 24 h. The EPS were precipitated as gummy masses by the addition of ethanol and characterized as the important long chain glucose polymer known as dextran (Strain SF3 with 20 g/L yield). The chemical and rheological properties of the produced EPS were investigated. Dextrans produced by these strains have a backbone chain of α (1 → 6) linkages with α (1 → 3) branching. The rheological behavior of dextran solutions exhibited typical shear thinning and weak gel properties.