Kombucha's microbes and chemistry in one commercial brew
What it found
A commercial kombucha contained 200 microbial species, including Acetobacter, Komagataeibacter and Starmerella, and had high protein, high phenolics and low sugars.
The work was done on bottled drink samples, not in people.
What they found
Bacteria found
The most common bacteria were Acetobacter (57% of reads), Komagataeibacter (34%) and Gluconobacter (7%). The single most abundant species was Acetobacter estunensis, at about half of the reads classified to species.
Yeasts found
The most common yeast was Starmerella, at 77% of reads, followed by Hanseniaspora at 10%, Galiella at 5% and Zygosaccharomyces at 3%. The most abundant yeast species was Starmerella sp., at 78% of reads classified to species.
Sugars and protein
The kombucha had low sugars: glucose 1.87 g/L, sucrose 1.11 g/L and fructose 0.05 g/L. Protein content was 3.31 µg/mL.
Phenolic content
Total phenolics were 290.4 mg/100 mL, which the authors say is higher than green tea. They link phenolics to antioxidant activity.
Live microbes
The samples had 108 colony forming units per mL, which the authors say is 10-fold higher than reported in other kombucha studies. More yeast colonies grew than bacterial colonies.
Acidity and colour
The kombucha was highly acidic at pH 3.00 and reddish yellow in colour. It had an electrical conductivity of 669 µS/cm and 2.9 Brix%.
What the authors conclude
“The broad microbial diversity with proven health benefits for the human gut suggests kombucha is a powerful probiotic.”
Also in their conclusions
- They say kombucha has broad microbial diversity enriched with organic acid producing microorganisms, laying the groundwork for immense potential for health benefits.
- They say the dominance of yeast and bacterial strains and their crosstalk are essential for bioavailability in providing benefits to the healthy human gut.
- They call for further comparative studies on how variations in microbial diversity, brewing process, fermentation time, herbs and fruits affect the quality of kombucha and its impact on health.
How it was done
The authors say kombucha's health benefits likely come from the tea and from substances made by its microbes, but the microbial ecosystem in kombucha had not been fully documented.
They took original base kombucha from The Good Brew company, made from 75% green tea and 25% oolong tea, sold in 330 mL glass bottles. They sequenced the DNA of the bacteria and yeasts and measured sugars, protein, phenolics and other physical and chemical properties.
What it can’t tell you
- This study looked only at the microbes and chemistry of one company's kombucha. It did not test kombucha in people, so it cannot show what drinking it does to human health.
- The authors' ideas about gut benefits, diabetes and obesity come from what is known about the microbes and their substances, not from measuring health effects in people.
Who paid
- Conflicts
- The authors declare no conflict of interest. Marc Cohen is co-owner of Extremely Alive Pty Ltd., which produces wellness tonics based on Good Brew Kombucha.
- Authors work at
- RMIT University, Australia; The University of Western Australia, Australia
The paper
- Title
- Microbial Diversity and Characteristics of Kombucha as Revealed by Metagenomic and Physicochemical Analysis
- Type
- Study
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Kaashyap M, Cohen M, Mantri N (2021). Microbial Diversity and Characteristics of Kombucha as Revealed by Metagenomic and Physicochemical Analysis. Nutrients. doi:10.3390/nu13124446Free full textPubMed 34960001DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error