Microbial Interactions in Kefir: A Natural Probiotic Drink

GARROTE G L; ABRAHAM A G; DE ANTONI G

Biotechnology of Lactic Acid Bacteria: Novel Applications

Wiley-Blackwell

Lugar: Ames, IO; Año: 2010; p. 327 - 340

Kefir is a fermented milk originated in the Caucasian Mountains that is obtained by incubation of milk with kefir grains. These grains contain a relatively stable and specific microbiota immobilized in a matrix of polysaccharides and proteins. Numerous species of lactic acid bacteria, acetic acid bacteria and yeast, held together in the matrix, exist in a symbiotic relationship.  The microbial interactions in kefir are very complex due to the composition of kefir grains. In this microbial ecosystem a delicately balanced population of microorganisms occurs, each interacting with and influencing the other members of the population. In kefir grains the balanced population of microorganisms determines the synthesis of biologically active metabolites that are essential for the grains growth and the inhibition of external microorganisms, like pathogens and food contaminants. The interactions among microorganisms in kefir grains are species and strain specific. S-layer proteins of Lactobacillus kefir plays an important role in co-aggregation between Lact kefir and yeast Saccharomyces lipolytica and in the inhibition of Salmonella adhesion and invasion to Caco-2/TC7 cells.   The interactions between microorganisms in kefir are still not complete known. So the knowledge of microbial interaction will be the basis for understanding the kefir grain ecosystem and its probiotic properties.