Skin Microbiota of Desmognathus quadramaculatus as an Inhibitor of Fungal Growth
Claire M Lamberg
Committee: JJ Apodaca, Jeff Holmes, Steve Cartier
The objectives of this research were to study the antifungal properties of cutaneous microbiota from a plethodontid salamander, Desmognathus quadramaculatus, and to see if bacterial isolates varied in behavior between sexed adults and juveniles. Because D. quadramaculatus inhabits an aquatic environment, the culturing of its residential bacteria offers a look into the symbiotic micro-communities of the ecology of an aquatic amphibian. Swabs were taken of the skin from each captured salamander after rinsing off any transient growth, and residential bacteria were cultured and isolated in R2A-agar, a low nutrient agar used for culturing bacteria found in potable water. For two weeks the isolates were then grown against a pathogenic ascomycete fungus, Mariannaea elegans, known for parasitizing and killing the eggs of several species of salamanders. Of the two species of bacteria isolated from each salamander, only one produced a halo of inhibition in the growth of M. elegans. To determine if the inhibitory growth was due to the bacteria itself or a compound it was producing, the bacteria was grown in Tryptic Soy Broth (TSB), spun in a centrifuge and filtered to create a cell-free supernatant. That product was then grown against M. elegans and no change in growth was observed. Applied and tested results from studies such as these can contribute to advances in the medical field, conservation of biodiversity, research of two growing fungal species that are negatively impacting amphibian species worldwide – Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, and help in the understanding of ontogenetic shifts as it pertains to salamanders.