Identification of thiamin producing lactic acid bacteria strains

TERAN, M.M.; LEBLANC, JG.; SAVOY DE GIORI, G.

San Miguel de Tucuman

Simposio; V Simposio Internacional de Bacterias Lácticas; 2016

CERELA

Vitamins are essential micronutrients found in various foods; however, a large percentage of the population fails to meet their daily requirements. Thiamine (vitamin B1), a B group water soluble vitamin, is an essential nutrient for life because all tissues need thiamine to function properly and is directly involved in energy production. Thiamine acts as a cofactor of various multi-enzyme systems associated with carbohydrate metabolism, branched chain amino acids and fatty acids. Also it plays an important role in nerve impulse conduction and the metabolism of oxygen. Human beings cannot synthesize thiamin so an exogenous supply of this vitamin is necessary to prevent nutritional deficiency, which is common not only in developing countries because of inadequate intakes, but also in industrialized countries as a result of chronic alcohol consumption. Therefore, it is common practice food fortification to increase the vitamin intakes. The proper selection of thiamin producing lactic acid bacteria (LAB) is an interesting alternative to enhance thiamin levels in foods. The aim of this study was to identify wild-type lactic acid bacteria (LAB) able to produce thiamin. Different LAB (22) strains were obtained from the culture collection (CRL) of the Centro de Referencia para Lactobacilos (CERELA-CONICET, Tucuman, Argentina) and belonging to Lactobacillus (L.) plantarum, L. reuteri, L. rhamnosus, L. casei and Lactococcus lactis were evaluated. Strains were grown in MRS broth, washed and then inoculated into a thiamin-free chemically defined culture medium (TCDM) followed by incubation at 37 °C for 16-18 h. This last step was repeated 4 times with the cultures showing good growth (observed by increased turbidity) while strains that did not grow in TCDM were not used in further studies. After the last incubation, samples were taken, boiled in acidic conditions and intra- and extracellular thiamin concentrations was determined by a microbiological method using Lactobacillus fermentum ATCC 9338 as indicator strain. Nine strains could grow and synthesize thiamin in TCDM. A wide variation in the B1 production was found amongst the microorganisms. Extracellular B1 levels varied between 2.7 and 6.7 µg/L while for intracellular B1 production was in the range of 2.8-4.3 µg/L. This property was a strain dependent-trait. The adequate selection and application of these LAB in the development of bio-enriched fermented foods is an innovative strategy to increase the concentration of thiamin in foods