Optimization of exopolysaccharide production from Pseudomonas stutzeri AS22 and examination of its metal-binding abilities

AimsTo investigate the effect of culture conditions and medium components on exopolysaccharide (EPS) production by Pseudomonas stutzeri AS22 and to access the EPS performance as a metal-binding exopolysaccharide. Methods and ResultsThe EPS production conditions of Ps.stutzeri AS22 in submerged culture were optimized using two approaches for EPS quantification, and its metal-binding capacity was evaluated using both single and mixed metal ions systems. Maximum EPS level was achieved after 24h of incubation at 30 degrees C with an initial pH of 80, 250revmin(-1) stirring level and 10% inoculum size. 50gl(-1) starch, 5gl(-1) yeast extract, 05gl(-1) NaCl, 14gl(-1) K2HPO4, 04gl(-1) MgSO4, 04gl(-1) CaCl2 and 1gl(-1) mannose were found to be the most suitable carbon, nitrogen, mineral and additional carbohydrate sources, respectively. From metal-binding experiments, the crude EPS showed interesting metal adsorption capacity adopting the order Pb>>Co>Fe>Cu>>Cd. Lead was preferentially biosorbed with a maximal uptake of 460mgg(-1) crude EPS. ConclusionsUnder the optimal culture requirements, EPS level reached 102gl(-1) after 24h of fermentation, seven times more than the production under initial conditions. According to the metal-binding assay, the crude EPS has potential to be used as a novel biosorbent in the treatment of heavy metals-contaminated water. Significance and Impact of the StudyOur results are interesting in terms of yield as well as efficiency for the potential use of the Ps.stutzeri exopolysaccharide as a metal-absorbent polymer in the bioremediation field.