Kombucha tea fermentation: Microbial and biochemical dynamics Somnath Chakravorty a,1 , Semantee Bhattacharya a,1 , Antonis Chatzinotas b , Writachit Chakraborty a , Debanjana Bhattacharya a , Ratan Gachhui a, ⁎ a Department of Life Science and Biotechnology, Jadavpur University, 188 Raja S. C. Mallick Road, Kolkata 700032, India b Department of Environmental Microbiology, Helmholtz Centre for Environmental Research — UFZ, Permoserstrasse 15, 04318 Leipzig, Germany abstract article info Article history: Received 28 June 2015 Received in revised form 24 December 2015 Accepted 31 December 2015 Available online 7 January 2016 Kombucha tea, a non-alcoholic beverage, is acquiring significant interest due to its claimed beneficial properties. The microbial community of Kombucha tea consists of bacteria and yeast which thrive in two mutually non- exclusive compartments: the soup or the beverage and the biofilm floating on it. The microbial community and the biochemical properties of the beverage have so far mostly been described in separate studies. This, however, may prevent understanding the causal links between the microbial communities and the beneficial properties of Kombucha tea. Moreover, an extensive study into the microbial and biochemical dynamics has also been missing. In this study, we thus explored the structure and dynamics of the microbial community along with the biochemical properties of Kombucha tea at different time points up to 21 days of fermentation. We hypothesized that several biochemical properties will change during the course of fermentation along with the shifts in the yeast and bacterial communities. The yeast community of the biofilm did not show much variation over time and was dominated by Candida sp. (73.5–83%). The soup however, showed a significant shift in dominance from Candida sp. to Lachancea sp. on the 7th day of fermentation. This is the first report showing Candida as the most dominating yeast genus during Kombucha fermentation. Komagateibacter was identified as the single largest bacterial genus present in both the biofilm and the soup (~50%). The bacterial diversity was higher in the soup than in the biofilm with a peak on the seventh day of fermentation. The biochem- ical properties changed with the progression of the fermentation, i.e., beneficial properties of the beverage such as the radical scavenging ability increased significantly with a maximum increase at day 7. We further observed a significantly higher D-saccharic acid-1,4-lactone content and caffeine degradation property compared to previ- ously described Kombucha tea fermentations. Our data thus indicate that the microbial community structure and dynamics play an important role in the biochemistry of the fermentation of the beverage. We envisage that combined molecular and biochemical analyses like in our study will provide valuable insights for better understanding the role of the microbial community for the beneficial properties of the beverage. © 2016 Elsevier B.V. All rights reserved. Keywords: Kombucha tea Microbial community structure and dynamics High throughput sequencing T-RFLP Change in fermentation Radical scavenging 1. Introduction Kombucha tea is a traditional non-alcoholic fermented beverage originating in the Orient and its inception is shrouded in mystery (Teoh et al., 2004). The beverage has gained substantial popularity espe- cially in the West because of a large number of claims regarding its ther- apeutic potential against a host of maladies. Some of its beneficial effects have already been demonstrated such as: anti-microbial, anti-oxidant, anti-carcinogenic (Jayabalan et al., 2011), anti-diabetic (Aloulou et al., 2012; Bhattacharya et al., 2013), treatment for gastric ulcers (Banerjee et al., 2010) and high cholesterol (Yang et al., 2009), etc. It has also shown to have impact on immune response (Ram et al., 2000) and liver detoxification (Loncar et al., 2000). Kombucha tea fermentation is the product of microbial activity by a consortium of both yeast and bacteria (Jarrell et al., 2000). The microor- ganisms, produce in the course of the fermentation, a thick cellulosic biofilm on the liquid–air interface. In contrast, most of the biofilms that have been studied to date are formed either on liquid–solid or air–solid interface (Nikolaev and Plakunov, 2007). The beverage is prepared by adding a small portion of the biofilm into sweetened (10% w/v) black tea. The broth also contains 10–15% of previously fermented Kombucha tea (called hereafter as old soup for convenience). The fermentation is static and the usual fermentation time is 7–12 days at room temperature (Dutta and Gachhui, 2006, 2007). Thus the Kombucha tea microbial community can be divided into two parts; the first one being the cellulosic biofilm and the second one thriving in the underlying liquid or soup. Studies have reported that the entire microbial spectrum of this beverage is dominated by acetic International Journal of Food Microbiology 220 (2016) 63–72 ⁎ Corresponding author at: Department of Life Science and Biotechnology, Jadavpur University, 188 Raja S. C. Mallick Road, Kolkata 700032, India. E-mail address: ratangachhui@yahoo.com (R. Gachhui). 1 Equal contributors. http://dx.doi.org/10.1016/j.ijfoodmicro.2015.12.015 0168-1605/© 2016 Elsevier B.V. All rights reserved. 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