Abstract:

The medium composition and culture conditions for conversion of linoleic acid (LA) to conjugated linoleic acid
(CLA) by Lactobacillus PC-3 were optimized by response surface methodology to obtain maximum conversion efficiency of
CLA. Culture medium type, lactose/ammonium sulfate concentration ratio, inoculums amount, culture time, LA concentration
and Tween-80 concentration were investigated by one-factor-at-a-time experiments. A three-variable, three-level response
surface design was used to optimize inoculum amount, culture time and LA concentration. The results showed that the optimal
conversion conditions of LA was MRS medium, inoculums amount of 3.0%, culture time of 43.0 h, LA concentration of 1.30‰
and Tween-80 concentration of 2.00 g/L. Under the optimized conditions, the experimental conversion efficiency of CLA was
6.87% compared to 6.96% from theoretical predictions, showing a relative error of 1.29% between both.

Key words: conjugated linoleic acid, Lactobacillus PC-3, response surface methodology, optimization