不透明红球菌转化合成α-酮异己酸的培养条件优化

Optimization of Transformation and Synthesis Conditions of α-ketoisocaproate by Rhodococcus opacus DSM 43250

利用基于非完全平衡块原理的Plackett-Burman法和响应面法对不透明红球菌(Rhodococcus opacus DSM 43250)转化合成α-酮异己酸(KIC)的培养条件进行优化,以提高KIC的产量.首先采用Plackett-Burman(PB)设计对影响KIC产量的6个因素的效应进行评价,筛选出具有显著影响的关键因素——接种量、装液量和初始pH,然后通过最陡爬坡实验和Box-Behnken实验设计对关键因素的最佳水平范围进行研究,并利用SAS软件回归分析建立了二次多项式模型,通过模型求解确定最佳培养条件为:接种量6.93%,装液量33.38 mL,初始pH 7.6.在优化后的培养条件下,KIC的理论最高产量为31.08 mg/L,在验证实验中KIC最高产量为30.97 mg/L,比初始产量23.93 mg/L提高了29.42%,为进一步的发酵放大奠定了基础.

This work aimed to optimize the conditions of biotransformation of α-ketoisocaproate （KIC） by Rhodococcus opacus DSM 43250 via a statistical analysis-based approach. Firstly, Plackett-Burman design was adopted to evaluate six key factors which influenced α-ketoisocaproate transformation, and inoculum size, liquid volume and initial pH were determined to be the three key factors. Subsequently, the steepest ascent experiments were conducted to reach the optimal response area. Finally, a second-order polynomial model was constructed via Box-Behnken design and regression analysis by SAS software. The optimal conditions consisted of： Inoculum size 6.93%, liquid volume 33.38 mL, and initial pH 7.6. Under the optimized conditions, the maximal KIC production was predicted to be 31.08 rag/L, and in the validation experiments, KIC production reached 30.97 mg/L, which was 29.42% higher than that without optimization （23.93 mg/L）. Fig 3, Tab 7, Ref 16