Bacillus cereus SG03 10L发酵罐中产胞外胆固醇氧化酶发酵条件优化
Fermentation conditions optimization of cholesterol oxidase in the broth by Bacillus cereus SG03 in a 10L fermentor
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摘要: 目的:优化菌株Bacillus cereus SG03在10L发酵罐中产胆固醇氧化酶的工艺条件,为该菌株的进一步应用提供依据。方法:在10L发酵罐中,通过单因素实验,分别考察了培养液起始pH、搅拌速率、溶解氧(DO)浓度对Bacillus cereus SG03产胞外胆固醇氧化酶的影响。结果:较佳的发酵条件为培养液起始pH6.8、搅拌速率250r/min、溶解氧(DO)浓度80%。在此基础上,对发酵过程进行了两阶段DO控制,发酵前20h DO控制在90%,然后调整为20%,直至发酵结束。较单一DO控制,最大胞外胆固醇氧化酶产量、生产效率分别提高了30.2%和20.0%,达到了1.38U/mL和0.03U/(mL·h)。Abstract: Objective: The technique of producing cholesterol oxidase by the strain of Bacillus cereus SG03 in a 10 L fermenter was optimized, in order to provide the basis for further application of the strain.Methods: The effect of pH of the culture medium, stirring rate and DO on the production of cholesterol oxidase in the broth by Bacillus cereus SG03 was studied in a 10 L fermentor.Results: The optimum fermentation conditions were initial pH at 6.8, stirring rate at 250 r /min and DO at 80%.Based on the results, a strategy of two stage DO manipulation was proposed, controlling DO at 90% before the 20 h and at 20% from the 20 h to at the end during the fermentation.The maximum COD activity in the broth and production efficiency reached 1.38 U /mL and 0.03 U / ( mL·h) , respectively improved30.2% and 20.0% higher than with one stage manipulation.
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