Kombucha as an antimicrobial sour

1. Kombucha as an
Antimicrobial Source
Stephanie Rodriguez
RISE Summer Bridge Program 2015

2. Introduction
Kombucha tea is obtained from infusion of tea leaves (usually from green and
black tea) by the fermentation of a symbiotic association of bacteria and yeasts
forming “tea fungus”. In the 1960s, science researchers in Switzerland
reported that drinking kombucha was similarly beneficial as eating yogurt
and its popularity increased. Today, it is sold worldwide in retail food stores
and online shopping websites but no research has been conducted in order to
prove its antimicrobial properties. Though it is claimed to be beneficial for
several medical ailments, very little or no clinical evidence is available for
that.

3. Purpose
• To inform the public of the effects of kombucha tea as an antimicrobial
source and if proven to be one, then set forth a more natural equivalent of an
antibiotic to the public.

4. Objective
• The objective of this is to investigate the microbiological effects of the
kombucha beverage.

5. Recipe for Kombucha
• Tap water (1 L) is boiled and during boiling 50 g sucrose is stirred in.
• 5 g tea leaves are added and removed by filtration after 5 min.
• After cooling to room temperature the tea is inoculated with 24 g tea fungus and
poured into a beaker (1 L) previously sterilized with boiling water. The growth of
undesirable microorganisms is inhibited by the addition of 0.2 L previously fermented
kombucha, thus lowering the pH. The beaker is covered with a paper towel to keep
insects away.
• In the next few days, the newly formed daughter culture will start to float and form a
clear thin gel-like membrane across the available surface. This is the newly formed tea
fungus available as a new layer above the old tea fungus which was inoculated to begin
the fermentation.

6. • At this time, the tea will start to smell fermented and there will be gas
bubbles appearing from the carbonic acid produced during the fermentation.
The mother culture will remain at its original volume as it sinks to the
bottom of the tea broth where it remains under the newly forming daughter
culture. After 10 to 14 days, a new tea fungus will have developed on the
surface of the tea as a disc of 2-cm thickness covering the whole diameter of
the beaker.
• The newly formed tea fungus is removed with a spoon and kept in a small
volume of fermented tea. The remaining beverage is filtered and stored in
capped bottle.
• *It is remarkable that 50 g sucrose/L provide the optimal concentrations of
ethanol and lactic acid. Longer fermentation produces high levels of acids
that may pose potential risks when consumed.

7. Methodology
• Culture common bacteria such as
*Helicobacter pylori - most common chronic infection in humans. Causes
abdominal pain, weight loss, nausea, and vomiting. Impairs absorption of
nutrients, altering the balance of iron, vitamin B12, folic acid, alpha-tocopherol,
vitamin C, and beta-carotene. (gram negative)
*Escherichia coli O157:H7- associated with a severe diarrheal disease called
hemolytic uremic syndrome. (gram negative)
*S. pneumonia – most frequent cause of middle ear infections (gram positive)
After growing the bacteria place a disk of the fungus, watch the growth of these and
record the effects of the tea fungus upon these bacteria.
If the bacteria grows around and on top the disk of fungus the supposed antimicrobial
properties will be proved to be a fallacy but if bacteria aren’t present around the disk then
its antimicrobial properties will be supported.

8. References
• Antibiotic Testing http://bulldog2.redlands.edu/fac/ben_aronson/hal/index1.htm
• Common Bacteria http://www.lifeextension.com/Protocols/Infections/Bacterial-Infection/Page-03
• Recipe http://www.culturesforhealth.com/how-to-make-kombucha
• Testimonials http://www.kombu.de/english.htm
• Wiley Online Library http://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12073/pdf