KOMBUCHA TEA: A BIORESOURCE FOR ACETICACID BACTERIA

Kombucha or Tea fungus is a traditional fermented beverageobtained during sweetened tea fermentation conductedby acetic acid bacteria (AAB) and yeasts. Historically,Kombucha appeared first in Asia and thereafter its usesand consumption spread from Russia, central Europe andthen over the world. It is composed of a cellulose floatingpellicle and a sour slightly and sparkling broth. However,in spite of vinegar, kombucha remained not well exploredmainly as a niche of AAB strains exploitable in biotechnologicalapplications. The aim of this study was to overviewthe occurrence of AAB in kombucha samples fromliquid and pellicle phases. Kombucha from black andgreen tea was obtained by inoculating a previously grownculture into a freshly prepared tea infusion containing10% of sucrose, 3% (w/v) of cellulose pellicle and 10%(v/v) of broth and led to fermentation up to 15 days in abatch system under aerobic condition. Titrable acidity reacheda maximum of 12 g/L at the end of fermentation inblack kombucha and 6 g/L in green one. pH dropped fromapproximately 3.7 until 2.75 for both samples as a resultof acids formation. Maximum ethanol accumulated at theday 15 did not exceed 0.5% (v/v) for both samples.Cellulose layer become thicker during fermentation, startingfrom 2-3 mm until 10 mm. AAB strains were isolatedfrom pellicle and liquid phases by sampling each 3 daysusing GYC and ACBS media. A total of 93 strains werecollecting during 15 days of fermentation of which 50 arecellulose producing. The majority of strains were tolerantto 5% (v/v) of ethanol and to 30% (w/v) of glucose. Thiswork opens an issue to explore the diversity of AAB fromKombucha focusing their ability to produce cellulose andto grow in low-acidic and sugary environment.