Aim and Background. Exopolysaccharides are natural polymers that are produced by Lactic acid bacteria (LAB), Bifidobacteria and Bacillus. Due to their characteristic physical and chemical properties, EPS are widely used in food industry as viscosifying, stabilizing, gelling, or emulsifying agents. EPSs synthesized by Bacillus spp. have comparatively elevated viscosity and superior pseudoplastic properties there has been increasing interest about them in recent years. The aim of the present study was isolation of two Exopolysaccharides (the cell-bound EPS (EPS-b) and the released EPS (EPS-r)) produced by10 strains of Bacillus spp. isolated from agricultures and identification of a strain that produces the highest amount of EPS.

Materials and Methods. 10 strains of Bacillus were overnight pre grown in MRS broth medium containing 2% (w/v) glucose at 37°C for 24-48h under aerobic conditions. The total amount of carbohydrate in the EPS was determined using the phenol/sulfuric acid method with glucose as the standard.

Results. Among 10 Bacillus spp, two strains had the highest amount bound EPS (EPS-b), maximum amount reached 43 mg/l (B5) and minimum amount reached 0.2 mg/l (B1, B4, B8, B9, B100). All strains synthesized EPS-r that maximum amount reached 229 mg/l (B7) and minimum amount reached 45mg/l (B8). Growth kinetics of the chosen strain (B7) in liquid medium with the production of EPS was investigated. The results show that the maximum production of EPS of the chosen strain (B7) was obtained in exponential growth phase. The level of EPS was then quite stable.

Conclusion. Results of this study showed that Iranian potential probiotic Bacillus species. have potential of EPS production.