Microbial Interactions in Kefir: A Natural Probiotic Drink.

GARROTE G; ABRAHAM A G; DE ANTONI G L

Biotechnology of Lactic Acid Bacteria: Novel Applications.

Wiley-Blackwell,

Año: 2009;

Kefir is a fermented milk originated in the Caucasian mountains 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 (LAB), acetic acid bacteria, and yeasts, held together into the matrix, exist in a symbiotic relationship. 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, eachinteracting 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 grain growth and the inhibition of external microorganisms like pathogens and food contaminants.Although microbial interactions in kefir grains have not yet been very well characterized, it has been established that these interactions are species- and strain specific. S-layer proteins of Lactobacillus kefir play an important role in coaggregation between this LAB and  Saccharomyces lipolytica as well as in the inhibition of Salmonella adhesion and invasion to Caco-2/TC7 cells. A better knowledge of microbial interaction will be the basis for  understanding the kefir grain ecosystem and its probiotic properties.