Optimizition of Linoleic Acid Isomerase Producing Conditions from Recombinant E.coli by Response Surface Method
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Abstract:
Conjugated linoleic acid (CLA) is widely found in a variety of foods. In order to obtain high yield of active CLA, the mutant linoleic acid isomerase was cloned and expressed in escherichia coli in this work. The single factor test determined that the optimal conditions for enzyme production were as follows: fermentation time 18 h, IPTG induced concentration 0.2 mmol/L, 20% liquid loading, initial pH7 of the medium, pre-induction bacterial biomass OD600=0.4, LA concentration 0.5 mg/mL, and ion concentration 0.02%. The response surface method was used to optimize the culture conditions of recombinant escherichia coli to improve the capacity of producing linoleic acid isomerase. According to the response surface method analysis results, the fermentation time, pre-induction biomass and LA concentration had significant effects on the expression of recombinant linoleic acid isomerase, and all of them were positive effects. The optimal combination of the three influencing factors was as follows: 19.5 h fermentation time, pre-induction biomass OD600=0.47, and LA concentration 0.57 mg/mL. Unde this condition, the maximum amount of LA to CLA catalyzed by linoleic acid isomerase was predicted to be 143.33 μg/mL. The results showed that the yield of CLA was 141.75±0.14 μg/mL, which increased by 107.5%.
