Development of an immunochemical method to detect Lactobacillus kefir.

GARROTE G L; SERRADELL M A; ABRAHAM A G; AÑON M C; FOSSATI C A; DE ANTONI G L

FOOD AND AGRICULTURAL IMMUNOLOGY

Taylor and Francis group Ltd

Lugar: United Kindom; Año: 2005 vol. 16 p. 221 - 233

0954-0105

Kefir is a fermented milk elaborated with kefir grains. They constitutes a natural ecological system composed by a protein-polysaccharide matrix on which a complex microbiota is naturally immobilised. The objective of this work was to develop an antibody based method in order to achieve simple and rapid way to quantify Lactobacillus kefir in a complex environment. Rabbit antisera against isolated S-layer proteins from Lactobacillus kefir and Lactobacillu. parakefir were obtained. Both antisera recognized the 21 strains of L. kefir and the 3 strains of L. parakefir analysed by dot-blot. By indirect ELISA, specific antiserum against L. kefir S-layer showed reactivity against pure cultures of both L. kefir and L. parakefir, but did not react with L. brevis cells. Competitive ELISA allowed quantification of L. kefir at concentrations ranging from 5x105 to 108 bacteria ml-1, but neither L. parakefir nor L. brevis pure cultures produced inhibition. Through this approach was possible to detect 108 L.  kefir  ml-1, in samples of  milk fermented for 48 h at 20 °C with different kefir grains. Competitive ELISA developed in our laboratory is a suitable method to detect and quantify L. kefir in milk and in consequence it could be applied to analysed the relationship between composition of microflora and probiotic and technological characteristics of the products