ANTIBACTERIAL ACTIVITY OF TEA KOMBUCHA AGAINST GRAM-POSITIVE AND GRAM-NEGATIVE BACTERIA

Kombucha is a fermented beverage obtained through the fermentation of sugared tea (Camellia sinensis L.) with symbiotic bacteria and osmophilic yeast. The beverage is well known to possess many prophylactic and therapeutic benefits which include antidiabetic, hepatoprotective, antioxidant, as well as reduction of arthritis, atherosclerosis, metabolic disorders, inflammatory problems, and even cancer. It is believed that most of these beneficial properties may be attributed to the polyphenols, organic acids specifically acetic acid and a host of other ingredients that are inherent to the raw materials or are produced as a result of the microbial fermentation.Therefore, studies suggest that due to its polyphenolic content, Kombucha tea can be used as a antibacterial potential. Therefore, the aim of this study was to assess the antimicrobial activity of Kombucha against Gram-negative bacteria: Salmonella Typhimurium ATCC 14028, Aeromonas hydrophila ATCC 7966, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Gram-positive bacteria: Staphylococcus aureus ATCC 25923 and Bacillus cereus ATCC 11778. Minimum Inhibitory Concentration (MIC) of Kombucha was determined using the broth microdilution method in 96-well microtiter plates. Briefly, 100 μL of Mueller Hinton Broth (MBH) was placed in each well of a 96-well plate, followed by the addition of the Kombucha tea and subsequent serial dilution. Bacterial suspensions were standardized by McFarland scale 0.5 and diluted at 1:20 (final inoculum 5.105 CFU/mL) and 10 μL were inoculated in each microplate well. After 24 h of incubation at 35 °C, MIC was defined as the lowest concentration that inhibited bacteria growth by visual reading. Minimal Bactericidal Concentration (MBC) was performed inoculating 10 μL from wells without bacterial growth on culture media specific for each bacteria: Enteric Hektoen Agar (Difco, Becton Dickinson, Sparks, MD, USA) was used for S. Typhimurium, A. hydrophila and P. aeruginosa; Eosin Methylene Blue Agar was used for E. coli, Baird Parker Agar was used for S. aureus and Mannitol Egg Yolk Polymyxin Agar for B. cereus. Plates were incubated at 35ºC for 48 h and MBC was defined as the lowest concentrations of compounds where no bacterial growth was visualized on agar plates. Kombucha showed MIC value of 25% of the pure tea and MBC of 50% for Gram-positive and Gram-negative bacteria evaluated. With these results, it was observed that the tea Kombucha displayed potential antibacterial against Gram-positive and Gram-negative bacteria.