Conjugated bioactive lipid production by Bifidobacterium strains isolated from human breast

V. TERAN; M.F. ZACARIAS; P. LUNA PIZARRO; G. VINDEROLA; R. MEDINA; C. VAN NIEUWENHOVE

S.M. de Tucumán

Simposio; IV International Symposium on Lactic Acid Bacteria: Food, Health and Applications; 2013

CERELA-CONICET

Among bioactive compounds, there are different conjugated fatty acids with beneficial health properties for humans. Conjugated linoleic (CLA) and linolenic acid (CLNA) are the most important ones in this group, being positional and geometric isomers of linoleic (LA) and linolenic acid (LNA), respectively. Many biological effects have been attributed to them, including anticarcinogenic activity. CLA has also properties as antiobesity and immunomodulatory compound, but CLNA isomers are most effective against cancer. Milk and meat of ruminants are the main source of these biolipids for humans. Many bacteria are able to form different conjugated fatty acids, included lactic acid bacteria, propionibacteria and bifidobacteria. This bioprocess allows the use of microorganisms as adjunct culture to increase the level of CLA and CLNA in fermented products or as probiotic strains for bioproduction at intestinal level. The aim of this work was to determine CLA and CLNA production in four Bifidobacterium strains isolated from human breast milk (at the INLAIN). Strains were cultured in MRScys, supplemented with LA or LNA for 48 h at 37 C under anaerobic conditions. Total conjugated fatty acid levels were first determined by UV method (233 nm), after which possitive strains were evaluated by gaseous chromatography. Results showed that strains were able to form CLA or CLNA in MRScys broth, having percentages of conversion from 1 % to 14% for CLA, and 1% to 65% for CLNA. The highest CLNA production was determined in Bifidobacterium animalis subsp. lactis INL2, selected for further studies. In this strain, LNA was mainly converted to the c9,t,11,c12 isomer. Increasing substrate concentrations were added to the broth (200 to 1000 ug/mL) to evaluate tolerance. No signifficant inhibitory effect of LA or LNA on bacterial growth was observed during 48 h compared to control (without fatty acid addition). According to results, 500 ug/mL of substrate was selected for further assays. Regarding time of conjugated fatty acids production, CLA/CLNA begins after 8 to12 h of incubation. This study demonstrates that bifidobacteria are good producers of conjugated bioactive lipid in vitro. Bacteria conjugated LNA more efficiently than LA. As far as we are concerned, this study informed for the first time CLNA production by strains in our country. Since CLNA has higher effect on cancer prevention than CLA, the use of these bacteria able to produce it could be an advance to develop functional products enriched in CLNA. For this purpose, bacteria must be carefully selected taking into account the optimal conditions for the biolipid production.