The E. coli AntiMicrobial Satellite (EcAMSat) mission investigated space microgravity effects on the antibiotic resistance of E. coli, a bacterial pathogen responsible for urinary tract infection in humans and animals. EcAMSat was being developed through a partnership between NASA’s Ames Research Center and the Stanford University Department of Microbiology and Immunology.
EcAMSat investigated spaceflight effects on bacterial antibiotic resistance and its genetic basis. Bacterial antibiotic resistance may pose a danger to astronauts in microgravity, where the immune response is weakened. Scientists believe that the results of this experiment could help design effective countermeasures to protect astronauts’ health during long-duration human space missions.
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The fundamental scenario of the experiment protocol started four days after deployment of the EcAMSat satellite from the International Space Station by allowing an initial growth and then starvation period for E. coli bacteria contained in 48 microfluidic wells. Both the wild type (occurring in nature) and a mutant strain lacking the rpoS gene (responsible for activating the general stress response) were used. This growth phase lasted 48 hours and provided enough time for the bacteria to reach and remain in stationary phase ~24 hours. After this period, a buffer-solution-plus-antibiotic mixture was dispensed into 3 sets of 12-well banks at three different antibiotic concentrations and was left to incubate for 48 hours. A fourth 12-well set was the control and received no antibiotic agent, only buffer solution. After 48 hours a fluid exchange occurred and alamarBlue®, a dye used as a metabolic indicator, was then introduced to all wells. Cellular metabolic processes reduce the dye and change the color from blue to pink, which was monitored in real time by a 3 color LED and detector optical measurement system for each well. The change in color was tracked for more than 48 hours. EcAMSat was capable of autonomous operation and stored all optics data for download during daily contacts with the ground system. Control experiments were performed on the ground to isolate the effects of microgravity from those of other stresses to which the cells were exposed, such as the chemical environment within the payload hermetic container. Overall, the experiment is helping us to understand the role of the rpoS gene in antibiotic resistance in microgravity, and may be useful for developing more effective treatments for future space travelers.
EcAMSat achieved full mission success on December 12, 2017, following the successful execution of the flight and ground control experiments. Publications are in progress. Results will be available upon publicationses.
Matin AC, Wang JH, Keyhan M, Singh R, Benoit M, Parra MP, Padgen MR, Ricco AJ, Chin M, Friedericks CR, Chinn TN, Cohen A, Henschke MB, Snyder TV, Lera MP, Ross SS, Mayberry CM, Choi S, Wu DT, Tan MX, Boone TD, Beasley CC, Spremo SM. Payload hardware and experimental protocol development to enable future testing of the effect of space microgravity on the resistance to gentamicin of uropathogenic Escherichia coli and its ss-deficient mutant. Life Sci Space Res. 2017 May 10. [DOI]
Padgen MR, Lera MP, Parra MP, Ricco AJ, Chin M, Chinn TN, Cohen A, Friedericks CR, Henschke MB, Snyder TV, Spremo SM, Wang J-H, Matin AC. EcAMSat spaceflight measurements of the role of ss in antibiotic resistance of stationary phase Escherichia coli in microgravity. Life Sci Space Res. 2019 Oct 31. [DOI]
Padgen MR, Chinn TN, Friedericks CR, Lera MP, Chin M, Parra MP, Piccini ME, Ricco AJ, Spremo SM. The EcAMSat fluidic system to study antibiotic resistance in low Earth orbit: Development and lessons learned from space flight. [DOI]