Zoh Science Illustrated · By Zoh Probiotics · Evidence checked 7 October 2026
The tiny version
Kefir has more than one kind of microscopic neighbour. Yeasts are different from bacteria, and researchers find different yeasts in different cultures. Dekkera and Kluyveromyces are two names from that research—not a compulsory pair or a score for how healthy the drink is.
Why are there yeasts in milk kefir?
Kefir research examines yeasts alongside bacteria because both occur in the fermentation community. A yeast finding is therefore not automatically a sign that a research sample has gone wrong. Equally, identifying a yeast in a food does not make every strain suitable for deliberate use.
Dekkera and Kluyveromyces are useful examples because they appear in different kinds of studies. One paper might describe the dominant yeast in a set of grains; another might isolate a strain and investigate particular properties. Those papers answer different questions.
Dekkera
Read the exact species and sample in the survey.
Kluyveromyces
Follow the strain code when discussing an isolate.
Your culture
Use information about the actual starter and method.
Meet the microbe · a shape guide
Kluyveromyces marxianus
A yeast with more than one outline
ATCC culture 22295 is described with cells ranging from round to oval and cylindrical, occurring alone, in pairs or short chains under the stated culture conditions. The portrait shows part of that variation.
This is the Kluyveromyces example in this chapter, not a depiction of Dekkera. Shape alone cannot establish either identity.
ATCC 22295: morphology description. Conceptual illustration, not microscopy. Colour and surface texture are artistic; not to scale. Shape cannot identify a strain, demonstrate health effects or verify Zoh product composition.
Where does Dekkera enter the kefir story?
In a study of grains from Italian regions, Garofalo and colleagues reported Dekkera anomala as the predominant yeast in the samples examined. They combined several analytical approaches rather than relying on appearance alone. [1]
“Predominant” describes a finding within that investigation. It does not mean every kefir must have the same dominant yeast. When comparing papers, check whether they examined grains, drinks or isolated cultures before trying to reconcile their lists.
A species name also needs to stay attached to the study that used it. If another source uses different terminology, establish the taxonomic relationship before treating the names as separate ingredients.
What is interesting about Kluyveromyces?
Diosma and colleagues isolated yeasts from milk and sugary kefir grains and selected strains for further investigation. Kluyveromyces marxianus CIDCA 8154 was one of the isolates studied beyond the initial screening. [2]
This is where the extra letters and numbers become useful. “CIDCA 8154” anchors the statement to a particular isolate. It prevents an observation about that isolate from drifting into a claim about every member of the genus.
The clinical lens
What did the promising tests actually involve?
The selected K. marxianus isolate was investigated for adhesion to intestinal-derived cells in vitro and survival through the gastrointestinal tract of mice. These are preclinical observations. They are not evidence that an unspecified kefir improves a human digestive symptom. [2]
Acid tolerance, adhesion in a cell model and survival in an animal can help researchers select candidates. Each still leaves questions about the preparation, amount, safety and outcome for an intended human use.
Why another survey can show a different list
Kalamaki and Angelidis identified multiple yeast genera in Greek kefirs, including Kluyveromyces. That work broadens the description of sampled kefirs; it does not convert the detected organisms into a set of clinically interchangeable probiotics. [3]
A strong reading habit is to label each paper before using it: survey, laboratory experiment, animal study or human trial. The label helps keep the conclusion proportionate.
What it means for your health
The selected evidence makes these yeasts interesting research subjects. It does not establish a personal dose or a therapeutic result from choosing a kefir because one of these names appears on a website.
For a specific health claim, ask for the relevant human evidence and the preparation tested. For ordinary food use, clear instructions and traceable product information are more useful than an unverified list of many organisms.
What does fizz tell you?
Fizz is an observation about a drink; it cannot identify the yeast present, establish alcohol content or rank probiotic benefit. Do not turn a yeast article into instructions for sealing an active milk ferment. Follow the vessel and lid arrangement specified for your culture.
If a batch behaves differently during warmer weather, record the temperature and timing before concluding that the culture has gained a new organism. Process observations can guide troubleshooting, but they are not a substitute for microbial testing.
Next: names that need context
The next chapter looks at Candida and Yarrowia, where familiar medical language can make a food-study finding especially easy to misread.
Questions people ask
Can I replace kefir starter with baking yeast?
No. Baking yeast is not a substitute for a suitable milk kefir culture.
Does every kefir have the same yeast?
No. Surveys show variation, and a supplier’s culture needs its own relevant information.
Research notes: follow the claim
Selected sources for this educational explainer, not a systematic review. Study types are labelled; no independent clinical review is claimed.
- Microbial survey. Garofalo C et al. Bacteria and yeast microbiota in milk kefir grains from different Italian regions. Food Microbiology. 2015;49:123–133. Source and bibliographic record.
- Laboratory and mouse study. Diosma G et al. Yeasts from kefir grains: isolation, identification, and probiotic characterization. World Journal of Microbiology and Biotechnology. 2014;30:43–53. Source and bibliographic record.
- Yeast identification study. Kalamaki MS, Angelidis AS. Isolation and molecular identification of yeasts in Greek kefir. International Journal of Dairy Technology. 2017;70:261–268. Source and bibliographic record.
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