Dr. Patrice Bouyer
C. albicans is a commensal fungus which under certain environmental cues (e.g., pH, oxidative stress) shifts morphology from spores to filamentous and becomes invasive within the human body. This work aims to identify the environmental gut cues responsible for this morphological shift. Estrogen (E2) becomes elevated during sepsis, thus the guiding hypothesis states that E2 may represent a factor responsible for the morphological change in C. albicans.
A calibration curve of growth of C. albicans in liquid minimal media (MM) was established using a spectrophotometer and correlating optical density with cell counts measured with a hematocyter. Liquid MM was inoculated in quadruplets of three different amounts of C. albicans. To test the effect of estrogen at 1nM concentration, E2 was added at the time of inoculation to one of each tube set, and fetal bovine serum was the positive control in another tube. All tubes were anaerobically grown over 3 nights in a shaking incubator at 30℃. Morphological changes were assayed using bright-field microscopy.
C. albicans was inoculated in amounts of 1, 2, and 4 million cells into sets of 4 tubes each based on the established growth curve. The MM relationship between OD and number of cells is described by the following equation: 1.06×106 + 1.83×10 7x + 1.68×10 7x 2 , R 2= 0.867. Adding E2 at 1 nM to the liquid media appeared to induce filamentous growth and budding, as with positive control 10% FBS.
Our preliminary experiments indicate that regardless of initial cell amount, tubes containing E2 seem to induce more filamentous growth in MM, as observed with FBS (positive control). Further experiments to determine effects of E2 at other concentrations would bring more insight, as well as trials combining E2 and FBS to explore if there is an additive or inhibitory effect on filamentation.
Zachara, Idalia Z.; Camp, Paige M.; Bouyer, Patrice; and Watters, Michael, "Testing Environmental Cues on Candida albicans Morphology" (2021). Symposium on Undergraduate Research and Creative Expression (SOURCE). 948.