Long-term exposure of bacterial cells to simulated microgravity

Previous space flight experience has demonstrated that microorganisms are just as ubiquitous in space habitats as they are on Earth. Numerous incidences of biofilm formation within space habitats have been reported; some of which were identified only after damage to spacecraft structures and irritation to astronaut's skin occurred. As we increase the duration of spaceflight missions, it becomes legitimate to question the long-term effects of microgravity on bacteria. To begin this assessment, Escherichia coli K-12 strain MG1655 was grown for one thousand generations (1000G) under low shear modeled microgravity. Subsequently, growth kinetics and the presence of biofilm were assessed in the 1000G strain as compared to a strain (1G) briefly exposed to LSMMG. Overall, the analysis revealed that (i) there was no obvious difference in growth kinetics between the 1G and 1000G strains, and (ii) although biofilm formation was not seen in the 1G strain it did in fact occur as exposure time increased. The results suggest that long-term exposure to the space environment likely favors biofilm formation in many organisms.