Function of cell-bound and released exopolysaccharides produced by Lactobacillus rhamnosus ATCC 9595

The physiological characteristics and function of the exopolysalcharide (EPS) produced by Lactobacillus rhamnosus ATCC 9595 were determined. The total quantity of EPS was rapidly increased to 496±20 mg/l during the exponential phase, and then maintained steadily during the stationary phase. During the exponential phase (18 h), the total EPS consisted of 61% cell-bound EPS (cb-EPS) and 39% released EPS (r-EPS), whereas the relative proportion of EPS during the stationary phase (48 h) was converted to 23% cb-EPS and 77% r-EPS. On gel permeation chromatography, cb-EPS was fractionated as a single peak of 8.6 × 10⁶ Da, whereas r-EPS was fractionated as two peaks with average molecular weights of 4.3 × 10⁴ and 8.6 × 10⁶ Da. Interestingly, both EPS species exhibited anticancer properties and cholera toxin-binding activities. Our results suggest that the EPS generated by L. rhamnosus ATCC 9595 might be suitable for use as a functional food or food supplement.