Effects of spaceflight on Candida Albicans Conference Paper uri icon

abstract

  • Astronauts and their body microflora experience simultaneous exposure to both radiation and microgravity during space exploration missions. In this study, Candida albicans was used as a model organism for studying the effects of simultaneous exposure to both radiation and microgravity, because it constitutes part of the normal human microflora and was isolated following various STS missions. To expand our knowledge of space microbiology and microbial ecology, we are examining for the first time the simultaneous effects of microgravity and radiation on fungal cells. The C. albicans cells were cultured in Sabouraud Dextrose Broth inside a Slow Turning Lateral Vessel (STLV) to stimulate microgravity and were concurrently exposed to 42.5 mRad of gamma radiation per hour. . Candida albicans was cultivated under five different conditions. Group 1 (Control 1g) cultures were not exposed to microgravity or radiation. Group 2 (SMG) cultures were exposed to simulated microgravity only. Group 3, cultures were exposed to gamma only. Group 4 (SSF) cultures received simultaneous exposure to microgravity and gamma radiation over a four day period. Group 5 (ISSF) received simultaneous and intermittent exposure to microgravity with gamma radiation exposure. In which cells were exposed simultaneously to radiation and microgravity, but were interrupted after 24 hours by placing under 1g and no radiation for 24 hours. Data was collected on growth, morphology, bud formation, metabolic activity and nuclear staining. Metabolic activity for cells in the control increased from 0 at inoculation to 37.45 % one day after inoculation; 69.6% by day 2 and 93.05% by day 3. Metabolic activity was higher under SSF (55.7%) than control by one day after inoculation, increasing to 67.8% by day 2 and 89.7% by day 3. Metabolic activity was highest under ISSF (61.05%) one day after inoculation, increasing to 67.05% by day 2 and 87.4% by day 3. Thus SSF and ISSF caused increased metabolic activity especially during the first 24 hours of exposure resulting in the observed shorter lag phase and increased growth. The C. albicans cells under SSF and ISSF were clumped together compared to the control and yielded higher biomass as well as higher optical density readings. Under SSF and ISSF cells increased formations of germ tubes, hyphaes, and pseudohyphaes. It is suggested from the data that simulated spaceflight induces alterations to yeast cell function that results in phenotypical alterations of growth and morphology. The National Aeronautics and Space Administration (NASA) Office of Education under the University Research Centers (URC) project, (Cooperative Agreements NNX08B47A and NNX10AQ16A), provided funding.

author list (cited authors)

  • Nwaobasi, N. C., Mathew, A. M., Ullah, O., Ford, J., Alaniz, R., & Olufisayo, J.

publication date

  • December 2011