Kefir grain microflora

From left: Kefir grain surface at a progressively increasing magnification. Large cells are yeasts and small cells are bacteria

Kefir is a cultured milk beverage, the result of microbial action of a wide community of microorganisms present in kefir grains on milk. The microorganism are lodged in the grains in a polysaccharide matrix of "kefiran". The resulting beverage has a uniform creamy consistency, a slightly acidic taste caused mostly by lactic acid, some effervescence due to carbon dioxide and a minute (<2%) concentration of alcohol due to the action of yeast cells also present in the grains. Kefir also contains a variety of aromatic substances which give it a characteristic flavour. Microorganisms present in the grains are called probiotic because they are beneficial to human health. There are lactobacilli, such as Lb. brevis, Lb. cellobiosus, Lb. acidophilus, Lb. casei, Lb. helveticus, Lb. delbrueckii, Lb. lactis, etc., lactococci, such as different subspecies of Lc. lactis, Streptococcus salivarius ssp. thermophilus, Leuconostoc mesenteroides and L. cremoris and a variety of yeasts (fungi), such as Kluyveromyces, Candida, Torulopsis, and Saccharomyces sp. (Micrographs of some of these microorganisms may be accessed from here).

There are many aspects of kefir featured on the Internet, from the origin of kefir in the Caucasus mountains, what it is, to information on how to make kefir at home and other aspects, including science and such scientific questions aas to whether the quality of kefir is affected by rinsing the kefir grains with water.

For information on microscopy, please contact the author.

Kefir grains were obtained from Dr. Edward Farnworth


Updated: March 12, 2013

©SCIMAT 2013