The Technics Research Of Producting The The Alginate Oligosaccharides Through Fermentation

In this article, the strain of Pseudoalteromonas elyakouii was used to hydrolyze alginate (the molecular weight is about 10 000Dn) to oligosaccharides of the alginate through fermentation.To reduce the cost of the fermentation medium and simplify the process of product purity , the (NH4)2SO4 was used as the solo-nitrogen-resource instead of the peptone in the medium. We add seaweed extract, glucose, lactose, some amino acids, pyruvic acid, citric acid, fumaric acid, urea into the medium respectively to improve the results of fermentation. The effect of these substances was investigated, the results show the product(oligosaccharides of the alginate) concentration of fermentation achieved high yield when adding 0.1g/L L-glutamine,0.1g/L citric acid,0.1g/L urea respectively .The fermentation conditions for Pseudoalteromonas elyakouii to produce the oligosaccharides of the alginate were studied and the optimum factors are selected through mono-factorial test and mix orthogonal design-direct. The optimal medium for producing the oligosaccharides of the alginate is composed of SA10g/L, (NH4)2SO4 10g/L, NaCl 20g/L, citric acid lg/L, MgSO 4 3g/L, and Na2HPO4 lg/L; the other optimum conditions are initial medium pH 7.5,inoculum 2%,culture temperature 24℃, rotational speed of shaker 100r/min. Under the above optimum fermentation conditions the OD235 can get 0. 917 (E00=0. 917).In the 10L fermentor, the strain of Pseudoalteromonas elyakouii was used to hydrolyze alginate (the molecular weight is about 10 000Dn) to oligosaccharides of the alginate through fermentation. When the pH control was not applied (free-fermentation), the optical density (OD 235) of production reached 0.916. To improve the results of fermentation,different pH control strategies were applied in all process of fermentation. The strategies are including three factors. The first is keeping the pH value to be 7.4 in the whole process. The second is according to the change of pH value in free-fermentation, keeping the pH to be 7.4 at the 0~36 hours or 36-72 hours, respectively. The third is according to the change rate of pH value in free-fermentation, keeping the pH value to be 7.4 at the 11-14 hours or 37-41 hours, respectively. The results show the optical density (OD 235) of production can reach 1.108 when keeping the pH value to be 7.4 at 36-72 hours in fermentation process. Comparing to the free-fermentation, the OD235 reduced 60% acutely when keeping the pH value to be 7.4 at 11-14 hours in fermentation.The strain of Pseudoalteromonas elyakouii was used to hydrolyze alginate (the molecular weight is about 10 000Dn) to oligosaccharides of the alginate through fermentation. The work to determinate the values of the volumetric oxygen transfer coefficient (KLa) in the fermentation was done in the 10L fermentation. Scaling up to 100L was carried out following a constant KLa criteria and volumetric airflow ratio per unit of volume. The effect of the scale-up was measured through comparing the DO, pH, biomass(OD6oo) and production(OD235) in both scales, the result show the scale-up had the well done, the production(OD23s) in 100L-fermentation was higher than 10L-fermentation.