Ergosterol Levels and Antifungal Resistance in Candida albicans Grown in Microgravity

Kenna White and Dr. Sheila Nielsen, Department of Microbiology and Immunology, Montana State University, Culbertson Hall, 100, Bozeman, MT 59717, United States

Candida albicans is a commensal, yet opportunistic fungal pathogen responsible for common human infections such as thrush and athletes’ foot. C. albicans undergoes a series of phenotypic and genotypic changes when exposed to high stress environments, and increased antifungal resistance has been observed after exposure to such conditions. In these studies, we are exploring adaptation of this yeast to the extreme/high stress environment of spaceflight microgravity. The proposed primary target for the antifungal drug Amphotericin B is ergosterol, a lipid found in the cell membrane. The expression of genes associated with the ergosterol biosynthetic pathway fluctuated over time in microgravity analog bioreactors as well as in spaceflight microgravity. Therefore, we quantified ergosterol levels in the context of antifungal resistance of C. albicans cultured in Amphotericin B (AmB) and the lipid sequestering agent Methyl-beta-cyclodextrin (MbCD) in microgravity conditions on the International Space Station. The C. albicans cells grown in spaceflight conditions reached a higher density than the terrestrial controls in both sham medium and in the presence of AmB. Ergosterol levels were also consistently higher in cells cultured in sham medium in flight than in those cultured as terrestrial controls.  Yet, cells cultured in spaceflight have diminished ergosterol levels when cultured in the presence of AmB, MbCD, or the combination thereof as compared to the similarly treated terrestrial controls. Consistent with the increased antifungal resistance, cells cultured in spaceflight reached a higher density in Amphotericin B and Methyl-beta-cyclodextrin conditions compared to the terrestrial controls. Together, these data suggest that differences in drug sensitivity are due to changes in ergosterol levels and C. albicans adapts to microgravity by demonstrating an upregulation of isolatable ergosterol.  

Additional Abstract Information

Presenter: Kenna White

Institution: Montana State University

Type: Oral

Subject: Microbiology

Status: Approved

Time and Location

Session: Oral 3
Date/Time: Mon 4:30pm-5:30pm
Session Number: 331
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