Does Kombucha Have Bacteria in It? A Comprehensive Look

January 4, 2026 •

3 min read

According to Cultures for Health, the SCOBY used to create kombucha contains more than 50 different varieties of probiotics, including beneficial strains like Bifidobacteria and Lactobacillus. This means, unequivocally, that kombucha has bacteria in it, and these microorganisms are what give the fermented tea its unique properties and potential health benefits.

Quick Summary

Kombucha is a fermented tea containing a symbiotic culture of bacteria and yeast (SCOBY). This process produces beneficial bacteria, or probiotics, which are safe and contribute to gut health. Commercial kombucha is regulated for safety, while homemade versions require proper hygiene to prevent contamination.

Key Points

SCOBY is a bacterial and yeast colony: The fermentation process in kombucha is driven by a Symbiotic Culture Of Bacteria and Yeast (SCOBY).
Kombucha contains beneficial probiotics: The bacteria present are probiotics, which are beneficial for gut health and immune support.
Fermentation creates a safe, acidic environment: The organic acids produced during fermentation, like acetic acid, create a low pH that inhibits the growth of harmful pathogens.
Homemade brewing requires strict hygiene: To prevent contamination from molds or undesirable bacteria, proper sanitation of equipment and a healthy SCOBY are critical.
Brown sediment is normal: The brown, stringy residue found in kombucha is composed of harmless, healthy yeast cultures and is safe to consume.
Mold is a sign of contamination: Fuzzy, colored mold (green, black, or white) on the surface means the kombucha is unsafe and should be discarded.
Probiotic benefits vary: The specific strains and quantity of probiotics in kombucha can vary depending on the brewing process, so benefits may differ by brand or batch.

The Science Behind the 'Good' Bacteria in Kombucha

Kombucha's existence and health-promoting properties are entirely dependent on a living ecosystem of bacteria and yeast. This colony is known as a SCOBY, which is an acronym for Symbiotic Culture Of Bacteria and Yeast. The SCOBY, which looks like a thick, rubbery, pancake-shaped disc, is added to sweetened tea to begin the fermentation process.

The Fermentation Process Explained

During fermentation, the yeast within the SCOBY consumes most of the sugar in the tea, producing alcohol and carbon dioxide. Following this, the bacteria take over, consuming the alcohol and converting it into various organic acids, primarily acetic acid (which gives kombucha its vinegary tang), gluconic acid, and lactic acid. This symbiotic dance is what creates the tart, fizzy beverage.

Types of Bacteria and Yeast in Kombucha

The microbial composition of kombucha can vary depending on the initial culture, tea, and fermentation conditions, but common bacteria include:

Acetobacter: This bacterium is responsible for converting the alcohol produced by the yeast into acetic acid. Acetobacter also helps form the cellulose mat that makes up the physical structure of the SCOBY.
Lactobacillus: A common type of lactic acid bacteria, Lactobacillus has well-known probiotic functions and is found in many fermented foods.
Komagataeibacter: This genus of bacteria, which has been identified in many commercial kombucha products, also contributes to fermentation.

Common yeasts found in kombucha include Zygosaccharomyces and Brettanomyces.

The Difference Between Beneficial and Harmful Bacteria

While kombucha is full of good, health-supporting bacteria, proper brewing and storage are essential to prevent harmful contamination. The protective, low-pH environment created by fermentation naturally inhibits the growth of most pathogenic bacteria, such as E. coli and Salmonella. However, a non-sterile environment or incorrect brewing procedure, especially in homemade batches, can lead to issues.


Aspect	Beneficial Kombucha Bacteria	Harmful Contamination
Source	The Symbiotic Culture of Bacteria and Yeast (SCOBY).	Contaminated equipment, ingredients, or improper handling.
Purpose	To ferment the tea, producing probiotics and organic acids that create the beverage.	To exploit a non-sterile environment, posing a health risk.
Appearance	Healthy SCOBY, bubbles, and brown, stringy sediment (yeast) are normal.	Fuzzy, dry patches of mold (green, black, or white) on the surface.
Environment	Flourish in an acidic environment (low pH).	Prevented by the low pH of a healthy kombucha brew.
Result	A tangy, fizzy, probiotic-rich drink.	Potential illness, digestive issues, or an unpleasant brew.
Prevention	Use a healthy SCOBY, maintain proper hygiene, and check pH.	Practice strict sanitation and discard moldy brews immediately.

How to Tell if Your Kombucha Is Healthy

A normal, healthy kombucha brew has a distinctive, vinegary aroma. The presence of a new, creamy-white layer on top of the liquid (the baby SCOBY) and brown, stringy yeast particles floating in the brew are also completely normal signs of a vibrant culture. However, if you see green, black, or fuzzy-white mold on the surface, you must discard the entire batch and your SCOBY.

Health Benefits Associated with Kombucha's Bacteria

While research on the specific effects of kombucha is still emerging, the probiotics produced during fermentation are known to offer several health benefits, particularly related to gut health. These beneficial bacteria can help replenish the healthy microorganisms in your digestive tract, which can support your immune system and aid digestion. Many people turn to kombucha as a natural way to increase their intake of these beneficial microbes, alongside other fermented foods like yogurt and sauerkraut.

Conclusion

In conclusion, the presence of bacteria in kombucha is not only normal but is the very foundation of the beverage's creation. The symbiotic culture of bacteria and yeast (SCOBY) works in harmony to ferment sweetened tea, producing a range of beneficial probiotics and organic acids. These 'good' bacteria are what give kombucha its characteristic flavor and potential health benefits. By understanding the fermentation process and practicing proper hygiene, consumers can safely enjoy this probiotic-rich drink, whether homemade or store-bought. A healthy kombucha brew's acidic environment also serves as a natural defense against harmful bacteria, making it a safe addition to a healthy, balanced diet for most people. For individuals with compromised immune systems, it is always best to consult a healthcare professional before consuming live cultures.

Brew Dr. Kombucha offers a great resource on the health benefits associated with kombucha.

Frequently Asked Questions

Yes, the bacteria in kombucha are generally considered good for you. They are a type of probiotic, which can support digestive health by promoting a healthy gut microbiome.

The brown stringy sediment is healthy yeast and tea particles, which are a normal byproduct of the fermentation process. It is completely safe and normal to find in your bottle, indicating a healthy, active culture.

While commercially produced kombucha is generally safe, homemade kombucha carries a higher risk of contamination from harmful bacteria if not brewed in a clean, sanitary environment. Always ensure proper hygiene and discard any brew that appears moldy.

Pasteurization kills both good and bad bacteria. Therefore, most of the beneficial bacteria are removed during this process. Some manufacturers may add probiotic supplements back into the drink after pasteurization.

A contaminated kombucha brew will often have fuzzy, green, black, or white mold on the surface of the SCOBY or liquid. Any such signs indicate that the brew is unsafe and should be thrown out.

Yes, homemade kombucha can be safe if brewed with proper sanitation and a healthy SCOBY. The risk of contamination is higher than with regulated commercial brands, so strict hygiene is essential.

Probiotics in kombucha are the beneficial bacteria, such as Acetobacter and Lactobacillus, that are a result of the fermentation process. They contribute to the health-boosting properties of the drink.