Fitness of Outer Membrane Vesicles From Komagataeibacter intermedius Is Altered Under the Impact of Simulated Mars-like Stressors Outside the International Space Station

Abstract

Outer membrane vesicles (OMVs), produced by nonpathogenic Gram-negative bacteria, have potentially useful biotechnological applications in extraterrestrial extreme environments. However, their biological effects under the impact of various stressors have to be elucidated for safety reasons. In the spaceflight experiment, model biofilm kombucha microbial community (KMC) samples, in which Komagataeibacter intermedius was a dominant community-member, were exposed under simulated Martian factors (i.e., pressure, atmosphere, and UV-illumination) outside the International Space Station (ISS) for 1.5 years. In this study, we have determined that OMVs from post-flight K. intermedius displayed changes in membrane composition, depending on the location of the samples and some other factors. Membrane lipids such as sterols, fatty acids (FAs), and phospholipids (PLs) were modulated under the Mars-like stressors, and saturated FAs, as well as both short-chain saturated and trans FAs, appeared in the membranes of OMVs shed by both post-UV-illuminated and "dark" bacteria. The relative content of zwitterionic and anionic PLs changed, producing a change in surface properties of outer membranes, thereby resulting in a loss of interaction capability with polynucleotides. The changed composition of membranes promoted a bigger OMV size, which correlated with changes of OMV fitness. Biochemical characterization of the membrane-associated enzymes revealed an increase in their activity (DNAse, dehydrogenase) compared to wild type. Other functional membraneassociated capabilities of OMVs (e.g., proton accumulation, interaction with linear DNA, or synaptosomes) were also altered after exposure to the spaceflight stressors. Despite alterations in membranes, vesicles did not acquire endotoxicity, cytotoxicity, and neurotoxicity.

Metagenome-Assembled Genome Sequences Obtained from a Reactivated Kombucha Microbial Community Exposed to a Mars-Like Environment outside the International Space Station

“…The KMC samples exposed to Mars-like conditions and laboratory references were reactivated as previously described ( 1 ). The growth rates, cellulose-based pellicle yields, and enzyme activities in the KMC samples were different from those in the ground reference samples after reactivation ( 3 , 4 ). The KMC specimens that had been exposed to Mars-like UV radiation showed major functional alterations compared to the UV-protected samples.…”

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

“…In addition to the risk of contamination, undesirable changes in the fermentation process and activation of probable pathogenic factors present in genomes of kombucha community inhabitants must be investigated in detail in future studies. In our recent study, despite alterations in membranes, kombucha's EMVs did not acquire endotoxicity, cytotoxicity, or neurotoxicity (Podolich et al, 2020). Metagenome-assembled genomes did not show the presence of pathogenic microorganisms in KMC IMBG-1, neither before nor after the exposure experiment (Lee et al, 2021).…”

“…Results of this metagenomic study will be used for the design of robust, rationally assembled mini-kombuchas composed of both core community members and purposely selected microbial partners. The composition of extracellular membrane vesicles (EMVs), which are thought to mediate communication between cells within and across domains, was altered in the post-flight KMC community members (Podolich et al, 2020). The changed composition of membranes correlated with changes in EMV fitness: the activity of membrane-associated enzymes seemed to be increased by UV radiation.…”

“…Recently, two dominant bacterial strains of K. oboediens isolated from the dehydrated KMC biofilms (ESA BIOMEX), one maintained on Earth and another sent to space/Mars-like conditions on the ISS, had their genomes sequenced and extensively compared. Despite some differences in phenotypic features (Podolich et al, 2020), the genomic analysis revealed that their genomes were quite similar (de Carvalho et al, 2021;personal communication), which made us consider epigenetic events on the space-flown strain.…”

“…Several members of the KMC produce EMVs, which could serve a range of health-related purposes. In this case, microbial EMVs could act as a surrogate of probiotics, carrying the same bioactive molecules but limiting the risks associated with the administration of live bacteria (Kozyrovska et al, 2018;Podolich et al, 2020), or act as living edible vaccines.…”