Assessment of DNA sequencing, antibiotic sensitivity, and resistance in yeast cells and human skin microbiome isolates post-space travel and cosmic radiation exposure

Abstract

Background: The Maleth research program involved three consecutive spaceflight missions in which tissue samples from diabetic foot ulcers (DFUs), containing both polymicrobial bacterial populations and the model eukaryote Saccharomyces cerevisiae, were sent to the International Space Station (ISS). Each mission exposed these bacterial cells to low Earth orbit conditions—including microgravity and heightened radiation for approximately 30 days. Method: Upon return to Earth, the bacterial communities were carefully recovered, cultured and subsequently identified using MALDI-TOF©. To assess potential alterations in antibiotic resistance profiles, all recovered bacterial isolates were cultured and then were subjected to antimicrobial susceptibility testing via the VITEK® 2 automated system. In parallel, Saccharomyces cerevisiae cells were evaluated for genomic changes through targeted sequencing and comparative genetic analysis against Earth-based controls at Singleron Germany. Results: The results showed that Proteus mirabilis was among the most significantly impacted bacterial species, with its post-spaceflight counts showing statistically significant differences compared to ground controls. Moreover, the isolates of Proteus mirabilis exhibited increased resistance to antibiotics, suggesting that space conditions may exert selective pressure conducive to resistance development. In contrast, analysis of Saccharomyces cerevisiae demonstrated no detectable genomic changes across any of the space-exposed samples, under the tested spaceflight conditions although there is the possibility that the duration in space was short and not sufficient to bring changes in the genome. Conclusion: These findings suggest that exposure to space can induce antimicrobial resistance characteristics of bacterial pathogens, such as in Proteus mirabilis. The implications of this study highlight the potential risks posed by altered microbial behaviour during long-term space and their effects on AMR in patients.