Optimization of Carbon and Nitrogen Sources for Extracellular Polymeric Substances Production by MUT.2.

BACKGROUND

Bacterial Extracellular Polymeric Substances (EPS) are environmental friendly and versatile polymeric materials that are used in a wide range of industries such as: food, textile, cosmetics, and pharmaceuticals. To make the production process of the EPS cost-effective, improvements in the production yield is required which could be implemented through application of processes such as optimized culture conditions, and development of the strains with higher yield (. through genetic manipulation), or using low-cost substrates.

OBJECTIVES

In this work, the effects of carbon and nitrogen sources were studied in order to improve the EPS production by the submerged cultivation of MUT.2.

MATERIALS AND METHODS

The mesophilic microorganism MUT.2, was grown and maintained in the Luria Bertani agar. The initial basal medium contained: glucose (20 g.L), yeast extracts (5 g.L), KHPO (6 g.L), NaHPO (7 g.L), NHCL (0.7 g.L), and MgSO (0.5 g.L). For evaluating the carbon and nitrogen sources' effect on the fermentation performance, cultures were prepared in 500 mL flasks filled with 300 mL of the medium. The single-factor experiments based on statistics was employed to evaluate and optimize the carbon and nitrogen sources for EPS production in the liquid culture medium of MUT.2.

RESULTS

The preferred carbon-sources, sucrose and glucose, commonly gave the highest EPS production of 8.32 and 6.37 g.L, respectively, and the maximum EPS production of 8.87 g.L was achieved when glutamic acid (5 g.L) was employed as the nitrogen source.

CONCLUSIONS

In this work, the culture medium for production of EPS by MUT.2 was optimized. Compared to the basal culture medium in shake-flasks and stirred tank bioreactor, the use of optimized culture medium has resulted in a 53% and 73% increase in the EPS production, respectively.