Kombucha as an Antimicrobial SourceStephanie Rodriguez

RISE Summer Bridge Program 2015

IntroductionKombucha 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.

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.

Objective

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

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.

• 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.

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.

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