title: Sequence-based analysis of the microbial composition of water kefir from multiple sources.
abstract: Water kefir is a water-sucrose-based beverage, fermented by a symbiosis of bacteria and yeast to produce a final product that is lightly carbonated, acidic and that has a low alcohol percentage. The microorganisms present in water kefir are introduced via water kefir grains, which consist of a polysaccharide matrix in which the microorganisms are embedded. We aimed to provide a comprehensive sequencing-based analysis of the bacterial population of water kefir beverages and grains, while providing an initial insight into the corresponding fungal population. To facilitate this objective, four water kefirs were sourced from the UK, Canada and the United States. Culture-independent, high-throughput, sequencing-based analyses revealed that the bacterial fraction of each water kefir and grain was dominated by Zymomonas, an ethanol-producing bacterium, which has not previously been detected at such a scale. The other genera detected were representatives of the lactic acid bacteria and acetic acid bacteria. Our analysis of the fungal component established that it was comprised of the genera Dekkera, Hanseniaspora, Saccharomyces, Zygosaccharomyces, Torulaspora and Lachancea. This information will assist in the ultimate identification of the microorganisms responsible for the potentially health-promoting attributes of these beverages.
authors.affiliation: Teagasc Food Research Centre, Fermoy, Co. Cork, Ireland; Alimentary Pharmabiotic Centre, University College Cork, Cork, Ireland; Microbiology Department, University College Cork, Cork, Ireland.
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Marsh
authors.forename: Orla
authors.initials: O
authors.lastname: O'Sullivan
authors.forename: Colin
authors.initials: C
authors.lastname: Hill
authors.forename: R Paul
authors.initials: RP
authors.lastname: Ross
authors.forename: Paul D
authors.initials: PD
authors.lastname: Cotter
mesh_terms: D001419:Bacteria / Q000145:classification* / Q000302:isolation & purification*; D044822:Biodiversity; D002170:Canada; D043302:Cultured Milk Products / Q000382:microbiology*; D005658:Fungi / Q000145:classification* / Q000302:isolation & purification*; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D006113:United Kingdom; D014481:United States
keywords: Tibicos; Zymomonas; food fermentation; sequencing; sugary kefir; water kefir