鞘氨醇单胞菌产3-苯氧基苯甲酸降解酶发酵条件的优化

以鞘氨醇单胞菌（Sphingomonas sp.）SC-1产3-苯氧基苯甲酸降解酶的酶活性为响应值，对其产酶条件进行优化。采用Plackett-Burman法对培养基组分和培养条件筛选显著性影响因素，并通过Box-Bohnken设计试验优化产酶条件，得到其最优培养基配方为：蛋白胨0.5 g/L、酵母膏0.5 g/L、葡萄糖0.8 g/L、硫酸镁0.01 g/L、3-苯氧基苯甲酸（3-phenoxybenzoic acid，3-PBA）质量浓度0.1 mg/mL；最优培养条件为：初始pH 8.33、种龄40.0 h、接种量4 mL/100 mL（种子液细胞浓度为108 CFU/mL）、转速180 r/min、温度30 ℃、装液量30 mL（250 mL锥形瓶）、培养时间37.75 h。在此条件下，发酵液酶活力可达1.870 5 mU/ g，比优化前（0.226 9 mU/g）提高8.24 倍。

Optimization of Fermentation Conditions for Production of 3-Phenoxyzoic Acid-Degrading Enzyme by Sphingomonas sp.

The present study was conducted to optimize fermentation conditions for the production of 3-phenoxybenzoic
acid-degrading enzyme by Sphingomonas sp. SC-1. The significant factors for the enzyme activity were screened from
medium components and culture conditions by Plackett-Burman design and optimized by Box-Bohnken design. The
optimal medium was composed of 0.5 g/L peptone, 0.5 g/L yeast extract, 0.8 g/L glucose, and 0.01 g/L MgSO4, 0.1 mg/mL
3-phenoxybenzoic acid. The optimal culture conditions were found to be as follows: initial pH, 8.33; inoculum age, 40.0 h;
inoculum size, 4 mL/100 mL (at a cell density of 108 CFU/mL); rotation rate, 180 r/min, culture temperature, 30 ℃; medium
volume in 250-mL conical flask, 30 mL; and culture time, 37.75 h. Under the optimal conditions, the enzyme activity was
1.870 5 mU/g, a 9.24-fold increase over that observed before optimization (0.226 9 mU/g).