Is the bacterium in kombucha alive?

November 18, 2025 •

4 min read

Kombucha has been consumed for over 2,000 years and is renowned for the live cultures it contains. This raises the fundamental question for many drinkers: is the bacterium in kombucha alive, and what does this mean for the beverage’s health benefits?

Quick Summary

The bacteria in kombucha are living microorganisms that drive the fermentation process. In raw and unpasteurized versions, these beneficial bacteria remain active, creating probiotics that contribute to the drink's potential gut health advantages. Pasteurization kills these live cultures.

Key Points

Live Cultures: Raw, unpasteurized kombucha contains active and living bacteria and yeast, often visible as sediment or 'floaters'.
SCOBY's Function: The Symbiotic Culture of Bacteria and Yeast (SCOBY) is the living organism responsible for fermenting sweetened tea into kombucha.
Pasteurization Kills Cultures: Heat treatment during pasteurization destroys the beneficial live bacteria and yeast, making the product shelf-stable but devoid of its natural probiotic content.
Source of Probiotics: The live bacteria in raw kombucha are probiotics, which are linked to supporting gut health and improving digestion.
Ongoing Fermentation: In raw kombucha, fermentation continues slowly over time, even under refrigeration, which is why its flavor and properties can subtly change.
Not a Mushroom: Despite being referred to as a 'mushroom,' the SCOBY is a colony of bacteria and yeast, not a fungus.

The Living Culture: A Symbiotic Relationship

Yes, the bacterium in kombucha is alive—at least in its raw, unpasteurized form. Kombucha is created through the fermentation of sweetened tea using a SCOBY, which stands for Symbiotic Culture of Bacteria and Yeast. This living, gelatinous mat is the heart of the brewing process, and its microbial members are active participants in transforming simple tea into a complex, fizzy, and tangy drink.

The Anatomy of the SCOBY

The SCOBY is not a single organism but a dynamic, thriving community of different microorganisms working in synergy. The most common bacterial genera found in kombucha include:

Acetobacter: These acetic acid bacteria convert the ethanol produced by the yeast into acetic acid, contributing to kombucha's distinct sour flavor and antimicrobial properties.
Lactobacillus: Some varieties of kombucha contain lactic acid bacteria, which are well-known for their probiotic potential and contributions to gut health.
Komagataeibacter: Certain species of this bacterium are responsible for synthesizing the cellulose fibers that form the visible pellicle, the mat-like structure often called the 'mother'.

The Fermentation Cycle

The process begins when the SCOBY is introduced to sweetened black or green tea. The yeast in the culture first consumes the sugar, producing ethanol and carbon dioxide. The carbon dioxide gives kombucha its natural fizz. Subsequently, the bacteria, primarily Acetobacter, consume the ethanol and convert it into various organic acids, most notably acetic acid. This dual-stage fermentation process is what gives kombucha its unique flavor profile, and as long as the kombucha remains raw and is not pasteurized, these microorganisms continue to thrive and multiply.

Raw vs. Pasteurised: A Critical Distinction

The biggest determinant of whether the bacteria in your bottle of kombucha are still alive is whether it has been pasteurized. This heat-treatment process is a major point of difference between products on the market.

Raw Kombucha

Raw kombucha, sometimes labeled 'unpasteurized' or 'alive,' has not been heat-treated. It contains a full spectrum of live, beneficial bacteria and yeasts, which are often considered the primary health benefit of the drink. The fermentation process continues in the bottle, albeit very slowly under refrigeration, which is why raw kombucha is typically stored in the cold aisle. The presence of these live cultures can be identified by the small, stringy, or gelatinous particles of SCOBY sediment floating in the liquid.

Pasteurised Kombucha

Pasteurization involves heating the kombucha to a high enough temperature to kill off microorganisms, ensuring a longer, shelf-stable product that does not require refrigeration. While this process eliminates the risk of harmful bacteria, it also destroys the very probiotics that many consumers seek. Some pasteurized brands may add shelf-stable probiotics back into the drink, but they will not possess the same complex and diverse live ecosystem found in a truly raw brew.

The Health Implications of Live Bacteria

The presence of live bacteria in raw kombucha is a key factor in its proposed health benefits. These microorganisms are often referred to as probiotics, which are known to help support a healthy gut microbiome. A balanced gut environment can contribute to better digestion, enhanced immune function, and overall well-being. However, it is important to remember that not all claims are fully backed by extensive human research, and the precise benefits can vary depending on the specific strains of microbes present.


Feature	Raw Kombucha	Pasteurised Kombucha
Live Probiotics	Contains a full, diverse spectrum of live bacteria and yeast.	Beneficial live cultures are eliminated by heat.
Shelf Stability	Unstable; requires refrigeration to slow fermentation.	Stable; can be stored at room temperature for long periods.
Flavor Profile	Complex and evolving; can become more vinegary over time.	Consistent and mild due to halted fermentation.
Cost	Often more expensive due to cold-chain logistics.	Generally less expensive, as it requires less complex handling.
Alcohol Content	Trace amounts that can increase over time if not refrigerated.	Stable and consistent, locked in place after heating.
Appearance	May contain visible sediment or 'floaters' from the SCOBY.	Clear and consistent in appearance, without floaters.
Primary Goal	To deliver beneficial live cultures and a raw, artisanal product.	To create a shelf-stable product with consistent flavor and reduced risk.

Conclusion

To answer the central question, the bacterium in kombucha is very much alive, provided you are drinking a raw, unpasteurized version. The symbiotic culture of bacteria and yeast, or SCOBY, is the living heart of kombucha, driving the fermentation process that creates the drink's unique flavor and probiotic properties. While pasteurized kombucha offers a safer, shelf-stable alternative, it lacks the living ecosystem that defines the traditional, gut-friendly beverage. For those seeking the full probiotic experience, reaching for a raw kombucha from the refrigerated section is the right choice. Understanding the difference between raw and pasteurized is crucial for consumers who want to know what they are truly putting into their bodies.

For more information on the health benefits and risks of kombucha, including those related to its live cultures, consult with a healthcare professional or reliable resources such as the MD Anderson Cancer Center.

Frequently Asked Questions

No. The bacterium is alive in raw, unpasteurized kombucha. In pasteurized varieties, the heat treatment process kills the live cultures, though some companies may add shelf-stable probiotics back in.

The SCOBY is a Symbiotic Culture Of Bacteria and Yeast that looks like a gelatinous, rubbery disk. While the visible pellicle is a cellulose byproduct, the active bacteria and yeast that make up the SCOBY are very much alive and driving the fermentation process.

The best way to know is to check the label for terms like 'raw,' 'unpasteurized,' or 'contains live and active cultures'. The product should also be sold from a refrigerated section, and you might see fine, stringy sediment in the bottle.

The live bacteria in kombucha are probiotics that are believed to support a healthy gut microbiome, aid digestion, and boost immune function. However, more human clinical studies are needed to fully confirm the extent of these benefits.

Yes. While pasteurized kombucha lacks the live probiotics, it still contains other beneficial compounds, like organic acids and antioxidants from the fermented tea. The decision depends on whether your priority is live cultures or a shelf-stable product.

The sediment, or 'floaters,' in raw kombucha is a natural part of the brewing process and a sign that the culture is alive and active. This is completely normal and safe to consume.

Homemade kombucha is typically alive, as it relies on a living SCOBY for fermentation. However, homemade brewing carries a higher risk of contamination from unwanted bacteria or mold, so proper sanitation is crucial.