Kombucha Fermentation and Its Antimicrobial Activity

Abstract

Kombucha was prepared in a tea broth (0.5% w/v) supplemented with sucrose (10% w/v) by using a commercially available starter culture. The pH decreased steadily from 5 to 2.5 during the fermentation while the weight of the "tea fungus" and the OD of the tea broth increased through 4 days of the fermentation and remained fairly constant thereafter. The counts of acetic acid-producing bacteria and yeasts in the broth increased up to 4 days of fermentation and decreased afterward. The antimicrobial activity of Kombucha was investigated against a number of pathogenic microorganisms. Staphylococcus aureus, Shigella sonnei, Escherichia coli, Aeromonas hydrophila, Yersinia enterolitica, Pseudomonas aeruginosa, Enterobacter cloacae, Staphylococcus epidermis, Campylobacter jejuni, Salmonella enteritidis, Salmonella typhimurium, Bacillus cereus, Helicobacterpylori, and Listeria monocytogenes were found to be sensitive to Kombucha. According to the literature on Kombucha, acetic acid is considered to be responsible for the inhibitory effect toward a number of microbes tested, and this is also valid in the present study. However, in this study, Kombucha proved to exert antimicrobial activities against E. coli, Sh. sonnei, Sal. typhimurium, Sal. enteritidis, and Cm. jejuni, even at neutral pH and after thermal denaturation. This finding suggests the presence of antimicrobial compounds other than acetic acid and large proteins in Kombucha.

Effect of medicinal plant type and concentration on physicochemical, antioxidant, antimicrobial, and sensorial properties of kombucha

“…Kombucha samples ultimately staged a gradual decrease in pH which is due to their buffering properties. In this regard, our results are in agreement with those of Chen and Liu (2000) and Sreeramulu, Zhu, and Knol (2000). …”

“…Antibacterial activities of kombucha samples occurred against both Gram‐positive and Gram‐negative pathogens. The efficiency of antibacterial activities can depend on organic acids, especially acetic acid and TFCs (Sreeramulu et al., 2000). A study by Greenwalt, Ledford, and Steinkraus (1998) evaluated the antibacterial activities of kombucha tea against Agrobacterium tumefaciens , B. cereus , Salmonella choleraesuis , S. typhimurium , S. aureus , E. coli , and Candida albicans , whereby the growths of all these bacterial species were considerably inhibited, except for C. albicans .…”

A review on health benefits of kombucha nutritional compounds and metabolites

“…Gluconic acid, ethyl-gluconate, oxalic acid, saccharic acid, keto-gluconic, succinic and carbonic acids were considered to be present in kombucha. Some of those acids were proved to have in vitro antimicrobial activity and improve sleep (Greenwalt, Steinkraus, & Ledford, 2000;Sreeramulu, Zhu, & Knol, 2000). Kombucha is a high source of glucuronic acid, which has a detoxifying effect against drug, bilirubin, and chemicals, as well as pollutants and excess of steroid hormones (Nguyen, Nguyen, Nguyen, & Le, 2015).…”

Detoxification of Patulin by Kombucha tea culture

“…Jayabalan et al (2014) reviewed the same growth observations of kombucha in black tea sweetened with sucrose. This fungus-like mixture of microorganisms and cellulose is likely the reason behind why kombucha is also called "tea fungus" (Sreeramulu et al, 2000). The color of kombucha broth was lighter in comparison with the color of black tea and this suggested that polyphenols did undergo microbial change in acidic environment by enzymes liberated by bacteria and yeast (Jayabalan et al, 2008).…”

“…Tea fungus broth is composed of two portions: a floating cellulosic pellicle layer and the sour liquid broth (Jayabalan, Malbaša, Lončar, Vitas, & Sathishkumar, 2014). The beverage has been claimed to be a prophylactic agent and to be effective against metabolic diseases, arthritis, indigestion, and various types of cancer (Sreeramulu, Zhu, & Knol, 2000). Beneficial effects and antioxidant activities of kombucha are attributed to a variety of active components and micronutrients produced during fermentation (Jayabalan et al, 2014).…”