Microbial Composition of SCOBY Starter Cultures Used by Commercial Kombucha Brewers in North America

Abstract

Kombucha fermentation is initiated by transferring a solid-phase cellulosic pellicle into sweetened tea and allowing the microbes that it contains to initiate the fermentation. This pellicle, commonly referred to as a symbiotic culture of bacteria and yeast (SCOBY), floats to the surface of the fermenting tea and represents an interphase environment, where embedded microbes gain access to oxygen as well as nutrients in the tea. To date, various yeast and bacteria have been reported to exist within the SCOBY, with little consensus as to which species are essential and which are incidental to Kombucha production. In this study, we used high-throughput sequencing approaches to evaluate spatial homogeneity within a single commercial SCOBY and taxonomic diversity across a large number (n = 103) of SCOBY used by Kombucha brewers, predominantly in North America. Our results show that the most prevalent and abundant SCOBY taxa were the yeast genus Brettanomyces and the bacterial genus Komagataeibacter, through careful sampling of upper and lower SCOBY layers. This sampling procedure is critical to avoid over-representation of lactic acid bacteria. K-means clustering was used on metabarcoding data of all 103 SCOBY, delineating four SCOBY archetypes based upon differences in their microbial community structures. Fungal genera Zygosaccharomyces, Lachancea and Starmerella were identified as the major compensatory taxa for SCOBY with lower relative abundance of Brettanomyces. Interestingly, while Lactobacillacae was the major compensatory taxa where Komagataeibacter abundance was lower, phylogenic heat-tree analysis infers a possible antagonistic relationship between Starmerella and the acetic acid bacterium. Our results provide the basis for further investigation of how SCOBY archetype affects Kombucha fermentation, and fundamental studies of microbial community assembly in an interphase environment.

Microbial and Chemical Profiles of Commercial Kombucha Products

“…Consistent with prior studies, we found that Brettanomyces was the predominant yeast in five of the kombucha products [ 35 , 42 ]. However, the three other common yeast genera present in kombucha cultures ( Zygosaccharomyces , Lachancea and Starmerella ) were largely undetected in the nine kombucha products [ 35 ]. Instead, two products and one sample of a third product showed predominance of Cyberlindnera jadinii .…”

“…Bacillus coagulans has many known effects on health and has been commonly added to foods due to its heat resistance [ 18 ]. Many studies have reported that acetic acid bacteria were more commonly found in kombucha products than lactic bacteria, with a study of over 100 commercial kombucha starter cultures reporting that Komagataeibacter was most prevalent and abundant [ 1 , 33 , 34 , 35 ]. Lactic acid bacteria (primarily Lactobacillus ) are less commonly used in kombucha fermentation to enhance its biological function or added as probiotics [ 36 ].…”

Kombucha Tea—A Double Power of Bioactive Compounds from Tea and Symbiotic Culture of Bacteria and Yeasts (SCOBY)

“…On the other hand, Zhao and Sui (2018) identified Saccharomyces cerevisiae and Arxula adeninivorans as major yeast strains, while Komagataeibacter saccharivorans (formerly Gluconacetobacter saccharivorans), Acetobacter sp., Komagataeibacter europaeus (formerly Gluconacetobacter europaeus), Acetobacter aceti and Limosilactobacillus fermentum (formerly Lactobacillus fermentum) where found as major bacterial representatives of Kombucha starter [64]. In the latest research on over 100 samples of Kombucha tea from North America, Komagataeibacter (K. europaeus, K. medellinensis, K. saccharivorans, K. nataicola, K. xylinus, K. rhaeticus), Acetobacter (A. senegalensis, A. tropicalis), Gluconobacter (G. oxydans), and Liquorilactobacillus nagelii were described as main bacteria, while Brettanomyces (B. bruxellensis and B. anomalus), Saccharomyces cerevisiae, Saccharomycodes ludwigii, Zygosaccharomyces bisporus, Starmerella davenpoortii, Schizosaccharomyces pombe were identified as yeast strains [65].…”

To Other Planets With Upgraded Millennial Kombucha in Rhythms of Sustainability and Health Support

“…Metagenomics studies also predicted opportunistic bacteria like Bacillus, Pseudomonas, etc. (Arikan et al, 2020;Villarreal-Soto et al, 2020;Barbosa et al, 2021;Harrison and Curtin, 2021), as well as bacteriophages and yeast viruses (Góes-Neto et al, 2021). There is a metabolic interplay between yeasts that convert sugar into monosaccharides and ethanol, in a liquid phase, and AAB that use glucose, fructose, and ethanol to produce organic acids and bacterial cellulose (BC), in a pellicle film phase (Villarreal-Soto et al, 2018).…”