DIVERSITY AND DYNAMICS OF CULTIVABLEPOPULATION OF ACETIC ACID BACTERIA ANDYEASTS IN KOMBUCHA

In recent years functional foods promoted with healthclaims have attracted increasing attention on the market.Among them kombucha is a fermented beverage widelyconsumed in Eastern Asian countries, but little is knownabout its constituent microbial communities. In this studytwo 12 days benchmark kombucha fermentations fromgreen and black tea were carried out. A culture-dependentapproach was applied both on exopolysaccharidic andliquid phases to monitor dynamics and diversity of aceticacid bacteria (AAB) and yeasts community. Among AABone main profile was observed (86% of strains); remainingstrains were grouped in 4 profiles by 16S/RFLPbasedanalysis. Whereas by (GTG)5/PCR typing sixteenclusters were obtained. 16S rRNA gene sequencing confirmedthe occurrence of Gluconacetobacter xylinus as predominantboth in green and black samples at 0, 6 and 12days of fermentation. Mainly on ACB medium minor bacterialgroups often colonizating tea leaves (Paenibacillusspp.), plants (Plantibacter spp.) and moisturing environments(Williamsia spp.), were detected starting from 6thfermentation day. Yeast population consisted of a restrictednumber of dominant species: Dekkera sp., Schizo -saccharomyces sp., Zygosaccharomyces sp., Dekkera sp.and Pichia sp. D. anomala was prevailing in both phasesthough all black and green kombucha fermentation times.Sc. pombe was detected only within 6 days of both greenand black tea and it was not isolated after 9 days, when the high ethanol-producing species D. bruxellensis was detected.Z. bailii was isolated from exopolysaccharidic ofblack tea from 6 to 12 days. Finally P. membranifacienswas detected occasionally at the end of the fermentativeprocess. For each species the degree of diversity wasdetermined by combined M13 and OPA20-based RAPDmethod. Cluster analysis showed that one to two prevailingbiotypes occurred through all the process.