Optimization of fermentation conditions for production of exopolysaccharide by Bacillus polymyxa

Production of exopolysaccharide (EPS) from a strain of Bacillus polymyxa was studied. Sucrose and potassium nitrate were found to be efficient carbon and nitrogen sources, respectively, for the production of the EPS. EPS production increased with the increase of sucrose concentration, probably due to the facilitated carbon uptake. Optimal pH was 7-8, and a sufficient supply of oxygen was needed for the EPS production. It was noted that the EPS synthesis by this B. polymyxa was growth-associated, indicating that a sufficient supply of nutrients was required for a high production of the EPS. As high as 54 g/l of EPS with a yield of 63% (g EPS/g sucrose) was obtained in 48 h of fed-batch cultivation with intermittent feeding of sucrose and potassium nitrate.