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

Mojtaba Khani; Ali Bahrami; Asma Chegeni; Mohammad Davoud Ghafari; ALi Mansouran Zadeh

doi:10.15171/ijb.1266

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

Iran J Biotechnol. 2016 Jun;14(2):13-18. doi: 10.15171/ijb.1266.

Authors

Mojtaba Khani¹, Ali Bahrami¹, Asma Chegeni¹, Mohammad Davoud Ghafari², ALi Mansouran Zadeh¹

Affiliations

¹ Department of Bioscience and Biotechnology, Malek Ashtar University, Tehran, Iran.
² Young Researchers and Elites Club, North Tehran Branch, Islamic Azad University, Tehran, Iran.

Abstract

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 (e.g. 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 Chryseobacterium indologenes MUT.2.

Materials and methods: The mesophilic microorganism Chryseobacterium indologenes MUT.2, was grown and maintained in the Luria Bertani agar. The initial basal medium contained: glucose (20 g.L^-1), yeast extracts (5 g.L^-1), K₂HPO₄ (6 g.L^-1), NaH₂PO₄ (7 g.L^-1), NH₄CL (0.7 g.L^-1), and MgSO₄ (0.5 g.L^-1). 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 Chryseobacterium indologenes MUT.2.

Results: The preferred carbon-sources, sucrose and glucose, commonly gave the highest EPS production of 8.32 and 6.37 g.L^-1, respectively, and the maximum EPS production of 8.87 g.L^-1 was achieved when glutamic acid (5 g.L^-1) was employed as the nitrogen source.

Conclusions: In this work, the culture medium for production of EPS by Chryseobacterium indologenes 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.

Keywords: Carbon source; Chryseobacterium indologenes; Extracellular polymeric substance; Medium composition; Nitrogen source; Stirred tank bioreactor.