Inferring the role of microorganisms in water kefir fermentations

Abstract

Water kefir is a slightly alcoholic, lactic and acetic beverage fermented by yeasts, lactic acid bacteria and acetic acid bacteria that are associated with the polysaccharide of the water kefir grains. In this study, the three main metabolic products of microorganisms were evaluated during a traditional 192-h water kefir fermentation and also after inoculating the microorganisms in fresh medium or sterilised broth from different fermentation stages. The first process to occur was alcoholic fermentation, carried out in particular by Saccharomyces cerevisiae. After 24 h, lactic and acetic acid accumulation was generated by Lactobacillus hilgardii and Acetobacter tropicalis. By the end of fermentation, ethanol had been almost entirely consumed and oxidised to acetic acid, possibly by a dissimilatory route of Acetobacter species. An original hypothetical diagram is proposed for the carbon flux from sucrose, and the metabolic role of the main yeasts and bacteria is assigned for the distinct stages of water kefir fermentation.

Proteomic Analysis of Lactobacillus nagelii in the Presence of Saccharomyces cerevisiae Isolated From Water Kefir and Comparison With Lactobacillus hordei

“…In contrast to milk kefir, there is only very limited research on water kefir. Most of the available studies focused on its species diversity ( Ward, 1891 ; Pidoux, 1989 ; Neve and Heller, 2002 ; Gulitz et al, 2011 ; Marsh et al, 2013 ; Laureys and De Vuyst, 2014 ; Martínez-Torres et al, 2017 ), or on the chemical and structural composition of the water kefir grains ( Horisberger, 1969 ; Pidoux et al, 1988 ; Pidoux et al, 1990 ; Waldherr et al, 2010 ; Fels et al, 2018 ; Xu et al, 2018 ). To date, several attempts have been made to understand the interactions of the microorganisms in water kefir.…”

“…The presence of oxygen allowed the proliferation of AAB, resulting in high concentrations of acetic acid ( Laureys et al, 2018 ). In addition, three main metabolic products were evaluated from the carbon flux from sucrose during 192 h of fermentation ( Martínez-Torres et al, 2017 ). After 24 h, lactic and acetic acid have been postulated to be initially produced by L. hilgardii and subsequently produced by Acetobacter spp., mainly A. tropicalis .…”

Contribution of autochthonous yeasts with probiotic potential to the aroma profile of fermented Guajillo pepper sauce

“…In comparison, our results show a final pH consistent with the lowest acidification power of yeast versus lactic acid bacteria. 20 Moreover, H. opuntiae population decreased significantly after 3 days ( Fig. 1), due to acid accumulation and decrease of pH in the Guajillo sauce.…”

Wine and Non-Dairy Fermented Beverages: A Novel Source of Pro- and Prebiotics

“…The starter cultures used in the fermentation are grains composed of water and polysaccharides and different microorganisms. Martínez-Torres, et al [64] found the occurrence of S. cerevisiae (responsible for alcoholic fermentation) in the early stage of the process and other yeasts as Candida californica and Pichia membranefaciens.…”