Studying Of The Production Of Beta-glucosidase In Submerged Fermentation

In this paper, the production of beta-glucosidase in submerged fermentation was preliminarily investigated.Using lywallzyme, snail digestase and cellulose action on the mycelia, the Aspergillus ficuum CN-67 protoplasts were obtained, then treated by UV light for certain time, the mutated strains were selected by shake flasks fermentation, and obtained a high-yield strains Aspergillus ficuum UV-29, and the enzymatic ability was from16.99±0.02IU/mL to 20.48±0.04IU/mL with good stability.Plackett-Burman and response surface methodology were used to optimize the submerged fermentation media of inulinase. A Plackett-Burman design was first used to evaluate the influence of six related factors: bran, bean dregs, NH4Cl, SDS, L-phenylalanine. Then Box-Behnken analysis method was used to further optimization. The optimum 50mL culture media in a 250mL flask consisted of 1.85g bran, 0.93g bean dregs, 4.98%NH4Cl, 0.4%CaCl2, 0.2%SDS, 0.1%L-phenylalanine with initial pH 5.5. The strain was cultured in an 180r/min rotating shaker at 30℃for 6d, with the enzyme activity at 30.48±0.01IU/mL.Based on the primary fermentation parameters, the law of growth and metabolism of Aspergillus ficuum UV-29 and the fermentation kinetic models were studied in an auto control bioreactor. The fermentation in bioreactor was successfully performed with a maximal biomass concentration (dry mass) of 1.17g/100mL and a maximal enzyme activity of 22.25±0.07IU/mL. Then the kinetic formulas of cell growth rate, beta-glucosidase production rate were inferred by controlling the specific biomass growth rate. The results of mathematic fitting between model calculated values and experimental values proved the validity and rationality of the kinetic models.