Conjugated linoleic acid conversion by dairy bacteria cultured in MRS broth and buffalo milk

CARINA P. VAN NIEUWENHOVE; RUBÉN OLISZEWSKI; SILVIA GONZÁLEZ; ADRIANA PÉREZ CHAIA

LETTERS IN APPLIED MICROBIOLOGY

Blackwel Publishing

Año: 2006

0266-8254

Abstract Aims: To evaluate strains of Lactobacilli, Bifidobacteria and Streptococci for their ability to produce conjugated linoleic (CLA) acid from free linoleic acid. Methods and Results: Eight dairy bacteria tolerant to linoleic acid were grown in MRS broth containing linoleic acid (200 µg ml-1) and conjugated linoleic acid was assessed. Seven bacteria were able to form CLA after 24 h of incubation, varying percentage conversion between 17 to 36 %. Lactobacillus casei, Lactobacillus rhamnosus, Bifidobacterium bifidum and Streptococcus thermophilus showed the highest linoleic acid conversion and were inoculated into buffalo milk supplemented with different concentration of linoleic acid. The production of CLA at 200 µg ml-1 of LA was two or three-fold in milk than MRS broth. All evaluated strains were able to produce CLA from high linoleic acid levels (1000 µg ml-1). Conclusions: The most tolerant strain to linoleic acid was Lact. casei. Lact. rhamnosus produced the maximum level of CLA at high LA concentrations (800 µg ml-1). The selected bacteria may be considered as adjunct cultures to be included on dairy fermented products manufacture. Low concentration of linoleic acid must be added to the medium to enhance CLA formation. Significance and impact of the study: The production of CLA by strains using milks from regional farms as medium offer a possible mechanism to enhance this beneficial compound in dairy products and those the possibility to develop functional foods.  Keywords: conjugated linoleic acid, linoleic acid, dairy bacteria, buffalo milk, lactobacilli, Streptococcus, Bifidobacterium