Abstract:A strain NJ-02 with high κ-carrageenan producing activity was acquired through screening and separation, and identified as Pedobacter sp. by physiology biochemistry experiment, 16S rRNA sequences determination and phylogenetic tree analysis. The optimal fermentation conditions were studied based on the single-factor and response surface experiment. The optimal conditions were obtained by single-factor experiment as follows: κ-carrageenan as carbon source (2.00 g/L), yeast extraction as nitrogen source (4.00 g/L), pH 7.00, inoculation amount 5%, temperature 30℃, and table speed 150 r/min. According to the single factor experiments, the carbon resource, nitrogen source, and pH were determined to be three key factors influencing κ-carrageenan enzyme production in fluid fermentation. A regression model for the yield of κ-carrageenan enzyme was established using a Box-Behnken design involving the above three factors with three levels. The best fermentation medium was found as follows: κ-carrageenan 2.15 g/L, yeast extraction 4.32 g/L, and pH 7.10. Under these conditions, the enzyme activity was 19.01 U/mL, which was 1.20 times as that of the original conditions. It provided the experimental foundation and theoretical basis for large quantity of κ-carrageenan and further study.
