Kefir: how it works on bacteria


A scientific study has shown how a substance produced by yeast in the bevanda probiotics Kefir iinhibits pathogenic bacteria, including Vibrio cholerae e Salmonella enteric, cause of disease onset. This component, called tryptophan acetate, acts decisively by interrupting communication between bacteria. The discovery could inspire the development of new ways to deal with bacteria resistant to the action of antibiotics.

What is Kefir

Kefir is a product derived from milk – it retains a small part of the initial lactose and is not produced by coagulation of casein proteins – and therefore considered a dairy product in all respects. It is a good source of proteins with high biological value, calcium, phosphorus and vitamins – especially of group B, in particular vitamin B2 (riboflavin) and vitamin A. Produced from whole milk, it also has a modest quantity of saturated fats and cholesterol. Thanks to the activity of the microorganisms present inside the kefirit is a food well tolerated by lactose intolerant and, above all, an ally for the well-being of the gastro-intestinal tract.

In the kitchen, natural kefir can be used in the preparation of cakes, biscuits, bread and dough for focaccia and pizza, as it promotes leavening and makes them softer. Also ideal in the savory version, as a sauce to accompany vegetables, meat and fish. In this case kefir facilitates digestion, because favors l’assimilation of animal proteins.

Benefits of kefir

This fermented milk-based drink originating from Tibet and the Northern Caucasus is also easy to prepare at home, by infusing the milk with kefir grains, which are a starchy matrix containing a symbiotic community of lactic acid bacteria, acetic acid bacteria and yeasts. Kefir has many health benefits, including the lowering of cholesterollto reduce inflammation and the exercise of a antioxidant effect. In common with other probiotics, kefir also has antimicrobial properties, high calcium and phosphorus content, constituents of bone hydroxyapatite. It also turns out to be a valid ally during growth and in old age; the need for these minerals also increases during pregnancy and breastfeeding.

Kefir is rich in folic acid (vitamin B9), an essential supplement not only for pregnant women, but also during pregnancy. menopausewhat an excellent defense against theosteoporosis they mood swings.

Kefir interrupts bacterial action: study

Researchers at Ben-Gurion University of the Negev (BGU) in Israel have now discovered that a type of yeast contained in kefir called Kluyveromyces marxianus secretes a molecule that interrupts bacterial communication. Scientists were already aware that some plants and algae were capable of producing this substance, called tryptophol acetate, but for the first time a yeast that produces it has been discovered.

The researchers highlighted that tryptophol acetate interferes with “quorum sensing” – a form of microbial communication – in several pathogenic bacteria. In quorum sensing, bacteria release signaling molecules into the surrounding environment. When the molecules reach a particular concentration, they trigger changes in the expression of genes in bacteria of the same species. These changes allow pathogenic bacteria to coordinate their activity based on their numbers. This coordination is necessary for some bacteria to defend themselves or attack their hosts.

In some cases, when they reach a certain density, microbes can join together to form a slimy, protective coating, or “biofilm,” on a surface.

Inhibited pathogenic bacteria

In laboratory cultures, the researchers found that tryptophol acetate had an inhibitory effect on the action of several pathogenic bacteria.

Some of the species tested were:

These results would constitute the first demonstration that the virulence of human pathogenic bacteria could be mitigated by molecules secreted in probiotic milk productssuch as yogurt or kefir.

Scientists focused in particular on the effect of tryptophol acetate on V. cholerae. They found that the substance blocked quorum sensing in this bacterium, and reduced its virulence, by changing the expression of bacterial genes that control quorum sensing. The researchers pointed out that this type of interference in bacterial communication may be common in complex environments where many different microorganisms live together, such as in probiotic food or the human gut.


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