The effects of microgravity on biological systems pose a significant challenge for long-term space missions, as it influences cellular aging, immune function, and stress resistance. One of the key cellular changes in microgravity is the alteration of telomere length—specialized repetitive DNA sequences at the ends of chromosomes that protect genetic information from degradation during cell division. Telomere length changes are associated with genomic instability and premature cellular aging. In microgravity, telomeres tend to lengthen, but upon return to Earth’s gravity, they become even shorter. These changes could have significant implications not only for astronaut health but also for biotechnological applications in space.
This study investigated the effects of microgravity on the resistance of Saccharomyces cerevisiae yeast to mandelic acid, a widely used cosmetic compound known for its antibacterial and exfoliating properties. Using yeast strains with different telomere lengths, minimum inhibitory concentrations (MICs) were determined through a drop assay, and growth was analyzed at various MIC concentrations (1 MIC, 0.5 MIC, 0.25 MIC) under different gravity conditions to assess growth dynamics.
Results from the drop test revealed that microgravity had only a slight impact, increasing the sensitivity of yeast with normal telomere length by 1.2 times. It was also observed that telomere length did not affect MIC values. Growth curve analysis showed that exposure to mandelic acid resulted in a lower final optical density (OD\(_{600}\)) in all tested samples compared to the control group, regardless of telomere length or gravity conditions. Additionally, a 1.3-fold extension of the lag phase was observed in all strains when 0.25 MIC of mandelic acid was added to the medium, indicating that mandelic acid prolongs adaptation and delays the growth of yeast cells. When 0.5 MIC of mandelic acid was introduced, a statistically significant effect of microgravity was observed only in the strain with short telomeres. Under microgravity conditions, this strain exhibited a higher OD\(_{600}\) than under normal gravity, suggesting improved survival or faster recovery from mandelic acid-induced stress.
To conclude, these findings suggest that microgravity influences yeast susceptibility to mandelic acid, particularly in strains with short telomeres. The observed changes in growth dynamics, including increased sensitivity and extended lag phase, highlight the potential impact of microgravity on cellular stress responses. Further research is needed to explore the molecular mechanisms underlying these effects and to determine whether similar responses occur in other eukaryotic models. Understanding these interactions could provide valuable insights for both space biology and the development of biotechnological applications in microgravity environments.