Optimization of a reconstituted skim milk based medium for enhanced CLA production by bifidobacteria

Aims:  To determine the effect of a range of supplements on the bioconversion of linoleic acid to conjugated linoleic acid (CLA) by Bifidobacterium breve NCIMB 702258 in reconstituted skim milk (RSM).
Results:  Seven supplements (yeast extract, casein hydrolysate, tryptone, l -cysteine hydrochloride, sodium acetate, sodium butyrate and sodium propionate) were identified as increasing the bioconversion of linoleic acid to c9 , t 11 CLA. Using these supplements, the percentage bioconversion of linoleic acid (0·35 mg ml^?l) to the c9 , t 11 CLA isomer was elevated from 15·5 ± 1·1% in 20% RSM (w/v) to 48·1 ± 2·2% in the supplemented RSM. Through additional supplementation of 20 mg m1^?1 inulin and optimization of inoculum and linoleic acid concentration, the percentage bioconversion to c9 , t 11 CLA was increased to 55·0 + 3·2%.
Conclusions:  Through supplementation, the concentration of CLA produced by bifidobacteria in RSM can be increased to levels comparable to those observed in the synthetic medium cys-MRS.
Significance and Impact of the Study:  The impact of 22 supplements on the production of the c9 , t 11 CLA isomer by the strain B. breve NCIMB 702258 in milk has been determined. The results provide an understanding of the factors, which influence CLA production by bifidobacteria in RSM.