Zoh knowledge bank · Kombucha · Updated 4 October 2026
The short version
Kombucha is made by a community of bacteria and yeasts. They change the sugar, acidity and flavour of tea. The exact community varies: a study of another kombucha cannot tell you which strains are in your jar.
What is living in kombucha?
A SCOBY is a community of bacteria and yeasts used to ferment sweet tea. The pale layer at the top is a cellulose mat, called a pellicle. Microorganisms are also present in the liquid, which is why starter liquid matters when you make a new batch.
You do not need to memorise a list of Latin names to brew well. It is more useful to understand the jobs the microbes do.
Yeasts help turn sugars into ethanol and carbon dioxide. The gas contributes to fizz when retained in the drink.
Acetic acid bacteria use ethanol and oxygen to produce acetic acid. This contributes to kombucha’s sharp, tangy flavour.
Cellulose-producing bacteria can build the pale pellicle at the surface. Its thickness is not a measure of probiotic strength.
Time, temperature, tea and the starting culture affect the result. Two jars need not develop at exactly the same speed.
Are all kombucha cultures the same?
No. Marsh and colleagues examined five cultures and their fermented liquids using DNA sequencing. They found differences in the microbial communities and reported bacterial and yeast groups including Gluconacetobacter, Lactobacillus and Zygosaccharomyces. Those findings describe the samples studied; they are not a certificate for every kombucha.
Names can also change as microbiologists revise classifications. A long list mixing old names, current names and repeated organisms can look impressive without telling you much.
Genus, species and strain: what is the difference?
These are increasingly specific ways to identify a microbe. Naming a genus such as Lactobacillus does not identify a particular strain.
Finding an organism, measuring how much is alive, and showing a benefit in people are three separate questions.
A strain count needs suitable testing and a clear definition. A living culture does not automatically qualify every organism in it as a clinically proven probiotic. We should not borrow a benefit demonstrated for a particular strain in a study and attach it to an untested home brew.
What does this mean for your next batch?
Keep useful brewing notes: tea and sugar quantities, starter-liquid amount, temperature, dates and pH readings. Change one variable at a time. This will tell you more about your own process than comparing the thickness of your pellicle with a photograph online.
For the practical method, use the step-by-step brewing guide. For claims about digestion or blood sugar, read our guide to kombucha health research.
Questions people ask
Does kombucha always contain Lactobacillus?
No. Its presence and abundance vary between cultures. Do not assume a particular organism is present without relevant testing.
Does a thicker SCOBY mean more probiotics?
No. Pellicle thickness is not a validated measure of live microbial count or health benefit.
Can I identify a strain from the look of my SCOBY?
No. Appearance can help you spot an obvious brewing problem, but strain identification requires laboratory methods.
Keep exploring
Kombucha SCOBY Guide: Buying, Using and Caring for Your Culture
Kombucha Health Benefits: What Human Research Actually Shows