Phenotypical Changes in Escherichia coli from Chronic Exposure to Simulated Microgravity
- Paper number
IAC-22,A2,IP,3,x69081
- Author
Mr. Collin Topolski, United States, Embry-Riddle Aeronautical University
- Coauthor
Dr. Hugo Castillo, United States, Embry-Riddle Aeronautical University
- Year
2022
- Abstract
Humans have adapted alongside bacteria and will continue to do so while in space. However, the effects of chronic exposure to the space environment on bacteria are still being explored. This work uses a custom 2D clinostat that has been previously validated to simulate microgravity conditions, specifically for bacteria, that operates both the control and microgravity treatments simultaneously. The purpose of this research was to identify the effects of microgravity on Escherichia coli while specifically looking at changes in biofilm formation, antibiotic resistance, acidic pH, and osmotic stress. Preliminary data with simulated microgravity (SM) has demonstrated that E. coli exhibits permanent phenotypical changes after four days of exposure. To further analyze this trend, biofilm development was measured using two assays (i.e., Crystal Violet and XTT) on E. coli samples that were previously on the clinostat for 4 and 22 days. The cells were grown in 6-well plates for 24 hours before the assays were completed. Both assays showed a higher biofilm biomass and metabolic activity from cells grown in SM compared to gravity. Increased biofilm growth has been related to increases in antibiotic resistance. To explore this relationship, the Kirby-Bauer assay was performed with a set of eight antibiotics. Initial findings revealed a significant increase in the resistance to some antibiotics, in direct response to the SM environment. The third experiment, testing acidic pH and osmotic stress tolerance, consisted of growing E. coli in nutrient media acidified to pH 4 and with an NaCl concentration gradient ranging from zero to ten percent in one percent increments. Cells grown in SM demonstrated larger growth inhibition compared to control under acidic stress and became completely inhibited after 4% NaCl. This information could potentially be utilized to develop new methods for controlling pathogenic bacteria in space. These studies are novel as they explore chronic effects of SM and analyze multiple phenotypical changes that can impact missions in space. Expanding on this current work, additional models and research-driven hypotheses are being investigated, such as the cell-cell interaction of Vibrio fischeri in SM as well as chronic exposure to sub-lethal gamma irradiation both in combination with the clinostat and individually.
- Abstract document
- Manuscript document
(absent)