THE INHIBITORY EFFECTS OF SOIL BACTERIA ON BATRACHOCHYTRIUM DENDROBATIDIS

Emily Yalda, Northeastern Illinois University

Emily Booms is the faculty sponsor of this poster.

Description

Recent amphibian extinctions and population declines are due to the sudden appearance of chytridiomycosis, an infectious disease in amphibians, caused by the parasitic chytrid fungus Batrachochytrium dendrobatidis or Bd. Parasites do not usually cause extinction of their hosts, or they, too, would go extinct, but in the case of Bd, it is killing frog hosts at an unexpectedly high rate. Bd is a parasite that requires a host for survival and reproduction. During Bd reproduction, zoospores are released from mature zoosporangia of the fungi which then target the skin of larval and adult amphibians. Once these spores invade the amphibian, they thicken the outer layer of epithelial cells, making it difficult for gas exchange to occur which is essential for breathing. Initial data from a 2010 study shows that Illinois amphibians may be in trouble and the percent of amphibians carrying this fungus is surprisingly high. Recently, research conducted in 2018 reveals that while the fungus persists as virulent as ever, the surviving amphibian species and populations are less susceptible, allowing them to resist the effects of the fungus. Our question is to identify what factors are contributing to this resistance in the Midwest. One determinant suggested in the literature is that soil composition in the surrounding ecosystem inhibits the effects of the fungus. In our study, we collected soil samples from three aquatic suburban locations in Illinois and isolated bacteria from them. We then exposed two different strains of Bd zoospores (JEL213 and JSOH1) to the different bacteria-conditioned media and counted live versus dead zoospores using Trypan blue staining under a hemocytometer 1, 4, 6, and 11 days post-exposure. We hypothesize that over time, the survival of the zoospores will be inhibited by the antifungal peptide(s) in the conditioned media, having been secreted by the soil bacteria. If zoospore survival decreases over time, it suggests that the amphibians that pick up these soil-dwelling species of bacteria could be protected from Bd zoospore exposure. If zoospores are inhibited, the soil bacteria-conditioned media will be analyzed to identify what compound(s) is/are responsible for the inhibitory effects. In addition, the species of bacteria that secreted these inhibitory compounds will be determined.

 
Apr 19th, 11:00 AM

THE INHIBITORY EFFECTS OF SOIL BACTERIA ON BATRACHOCHYTRIUM DENDROBATIDIS

Recent amphibian extinctions and population declines are due to the sudden appearance of chytridiomycosis, an infectious disease in amphibians, caused by the parasitic chytrid fungus Batrachochytrium dendrobatidis or Bd. Parasites do not usually cause extinction of their hosts, or they, too, would go extinct, but in the case of Bd, it is killing frog hosts at an unexpectedly high rate. Bd is a parasite that requires a host for survival and reproduction. During Bd reproduction, zoospores are released from mature zoosporangia of the fungi which then target the skin of larval and adult amphibians. Once these spores invade the amphibian, they thicken the outer layer of epithelial cells, making it difficult for gas exchange to occur which is essential for breathing. Initial data from a 2010 study shows that Illinois amphibians may be in trouble and the percent of amphibians carrying this fungus is surprisingly high. Recently, research conducted in 2018 reveals that while the fungus persists as virulent as ever, the surviving amphibian species and populations are less susceptible, allowing them to resist the effects of the fungus. Our question is to identify what factors are contributing to this resistance in the Midwest. One determinant suggested in the literature is that soil composition in the surrounding ecosystem inhibits the effects of the fungus. In our study, we collected soil samples from three aquatic suburban locations in Illinois and isolated bacteria from them. We then exposed two different strains of Bd zoospores (JEL213 and JSOH1) to the different bacteria-conditioned media and counted live versus dead zoospores using Trypan blue staining under a hemocytometer 1, 4, 6, and 11 days post-exposure. We hypothesize that over time, the survival of the zoospores will be inhibited by the antifungal peptide(s) in the conditioned media, having been secreted by the soil bacteria. If zoospore survival decreases over time, it suggests that the amphibians that pick up these soil-dwelling species of bacteria could be protected from Bd zoospore exposure. If zoospores are inhibited, the soil bacteria-conditioned media will be analyzed to identify what compound(s) is/are responsible for the inhibitory effects. In addition, the species of bacteria that secreted these inhibitory compounds will be determined.