Microgravity transforms Bacillus cereus 1272 into a more resilient infectious pathogen

The microgravity environment of the International Space Station (ISS) provides unique and vistas of opportunities for cutting-edge research in biological systems. Weightlessness profoundly influences physical and biological processes, making it a critical area of scientific research. This study examined the response of Bacillus cereus 1272, a significant food-borne pathogen, to simulated microgravity conditions through comprehensive in vitro (microbial growth kinetics, biofilm assay and antimicrobial assay) and in situ (bacterial survival assays within real food system) analyses. Investigations focused on multiple physiological parameters, including growth characteristics, cellular responses to cold stress, membrane fatty acid composition, morphological changes, biofilm production, and antimicrobial susceptibility. During a 24 h experimental period, B. cereus 1272 demonstrated significant adaptations under microgravity conditions compared to standard gravity environments. Key findings revealed a notably higher bacterial growth rate and increased membrane fatty acid unsaturation in microgravity. Substantial modifications were observed in cellular morphology, aggregation patterns, and biofilm formation. Critically, antimicrobial resistance significantly amplified under simulated microgravity conditions, presenting important implications for astronaut health, food safety during space missions, and potential challenges in long-duration space exploration. These results underscore the complex bacterial adaptive mechanisms in microgravity and highlight the necessity of understanding pathogen behavior in extraterrestrial environments, particularly for future interplanetary travel and extended space missions.