Production of conjugated linoleic acid by Propionibacterium freudenreichii ssp. shermanii

Abstract

The kinetics of linoleic acid isomerization to conjugated linoleic acid (CLA) by Propionibacterium freudenreichii ssp. shermanii JS was studied in pH-controlled batch and fedbatch fermentations. In batch fermentations supplemented with 600-2 000 μg·mL-1 linoleic acid, the rate of CLA formation was highest during the exponential phase of growth. By the end of the batch fermentations, high amounts of CLA corresponding to 80-87% conversion were accumulated with initial linoleic acid concentrations up to 2 000 μg·mL-L. In fed-batch fermentations, where 600 μg·mL-1 linoleic acid was added into the culture after exponential growth, a rapid but short conversion period occurred. Thus, both actively growing and non-growing cultures were able to effectively form CLA, However, the production rates per cell were significantly higher in growing cultures. This isomerization reaction could be a detoxification system for linoleic acid in the propionibacterium strain studied.