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Background and Objectives: Exopolysaccharides are linked to all form of polysaccharides found outside of the microbial cell wall. The aim of the current study was to investigate physicochemical characteristics of an exopolysaccharide produced by Lactobacillus pentosus.
 Materials & Methods: First, the exopolysaccharide was isolated under optimal conditions (glucose, 4.11% w/v; sucrose, 3.47% w/v; yeast extract, 3% w/v; peptone, 3% w/v; time, 30.92 h, temperature, 40 °C; inoculation size, 3.16% v/v; pH 7). Then, exopolysaccharide was purified and dried using freeze dryer. Physicochemical characteristics of the exopolysaccharide produced by Lactobacillus pentosus were assessed. Assessments included NMR test, water holding capacity, aqueous solubility index, antibiofilm activity, rheological test and inhibition of DPPH radical activity.
Results: Total quantities of the exopolysaccharide and biomass produced by Lactobacillus pentose included 0.225 and 0.405 mg/ml, respectively. Results of the NMR of exopolysaccharide generally showed presence of anomeric protons, cyclic protons and alkyls. Water solubility index and water holding capacity of the exopolysaccharide included 27.14 and 170%, respectively. The highest antibiofilm effects of the exopolysaccharide were demonstrated against Pseudomonas aeruginosa. The exopolysaccharide frequency-change rheological test showed typical pseudo-plastic non-Newtonian fluid behaviors. The DPPH radical scavenging activity demonstrated moderate antioxidant characteristics of the exopolysaccharide.
Conclusion: Results suggest that exopolysaccharide from Lactobacillus pentosus includes potentials to be used as a natural agent in foods.