Optimization of exopolysaccharide production from P seudomonas stutzeri AS 22 and examination of its metal‐binding abilities

Aims To investigate the effect of culture conditions and medium components on exopolysaccharide ( EPS ) production by Pseudomonas stutzeri AS 22 and to access the EPS performance as a metal‐binding exopolysaccharide. Methods and Results The 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 24 h of incubation at 30°C with an initial pH of 8·0, 250 rev min −1 stirring level and 10% inoculum size. 50 g l −1 starch, 5 g l −1 yeast extract, 0·5 g l −1 NaCl, 1·4 g l −1 K 2 HPO 4 , 0·4 g l −1 MgSO 4 , 0·4 g l −1 CaCl 2 and 1 g l −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 460 mg g −1 crude EPS. Conclusions Under the optimal culture requirements, EPS level reached 10·2 g l −1 after 24 h 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 Study Our 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.