Optimization of cholesterol oxidase production by Brevibacterium sp. employing response surface methodology

An ultrasound-assisted emulsification as a pretreatment for cholesterol oxidase production by submerge fermentation using Brevibacterium sp. in a batch system was studied. Medium improvement for the production employing response surface methodology (RSM) was optimized in this paper. The concentration of Tween-80, cholesterol and the time of ultrasonic pretreatment medium were further optimized by RSM. Results from RSM showed that the initial concentration of cholesterol, Tween-80 and pretreatment time exerted a significant effect on cholesterol oxidase production, but these factors did not exert a significant effect on cell growth. The improved medium consisted of 4.076 g/L cholesterol, 0.2932‰ (v/v) Tween-80, 22.361 (min) treatment time, and cholesterol oxidase production reached 1.483 U/ml after 36 h culture, which was 83.57% greater than the control medium.