Kombucha is a multispecies microbial ecosystem mainly composed of acetic acid bacteria and osmophilic acid‐tolerant yeasts, which is used to produce a probiotic drink. Furthermore, Kombucha Mutualistic Community (KMC) has been recently proposed to be used during long space missions as both a living functional fermented product to improve astronauts' health and an efficient source of bacterial nanocellulose. In this study, we compared KMC structure and functions before and after samples were exposed to the space/Mars‐like environment outside the International Space Station in order to investigate the changes related to their re‐adaptation to Earth‐like conditions by shotgun metagenomics, using both diversity and functional analyses of Community Ecology and Complex Networks approach. Our study revealed that the long‐term exposure to space/Mars‐like conditions on low Earth orbit may disorganize the KMC to such extent that it will not restore the initial community structure; however, KMC core microorganisms of the community were maintained. Nonetheless, there were no significant differences in the community functions, meaning that the KMC communities are ecologically resilient. Therefore, despite the extremely harsh conditions, key KMC species revived and provided the community with the genetic background needed to survive long periods of time under extraterrestrial conditions.
Figure S1. Stacked bar charts presenting the bacterial (A, B), yeast (C, D), and viral (E, F) components of postflight kombucha microbial communities (KMC‐b) and corresponding KMCs cultured within 2.5 year (KMC_c). (1: top, UV‐unprotected level; 2: middle, UV‐protected level; 3: bottom, UV‐protected level, 4: laboratory‐kept KMC samples during the exposure experiment; 5: the initial KMC sample). Dark and light blue colour for references (KMC_5 and KMC_4 respectively). The space exposed samples are represented in gradient colour of brown for yeasts, and green for viruses.
Figure S2. Relative abundance of the dominant bacterial genera (A) Komagataeibacter and (B) Gluconobacter.
Table S1. Alpha‐diversity parameters estimated for the experimental and control KMCs.