Date of Award

8-9-2014

Document Type

Open Access Thesis

Department

Environmental Health Sciences

First Advisor

Anindya Chanda

Abstract

A large number of facultative marine fungi are unexplored (Lai et al., 2007). They exist in the hypersaline environment with reduced growth and metabolism for an indeterminable period of time and are believed to have no ecological role. Here we report the discovery of one novel facultative Penicillium species that we named Penicillium virginium. We show that when transferred from its native ecosystem, a salt pond in San Salvador, Bahamas, to a laboratory fungal growth medium, Penicillium virginium demonstrates a higher growth rate in absence of salt than in presence of salt confirming that it is a facultative marine fungus. In an interaction experiment when Penicillium virginium was grown in a salt-free environment together with a known terrestrial saprophytic fungal pathogen model Aspergillus parasiticus, Penicillium virginium inhibited Aspergillus’ growth and metabolism. We show that this inhibition was caused by bioactive compounds released into the growth medium that were not only inhibitory to Aspergillus’ growth and metabolism, but also prevented growth of gram-positive bacteria including the methicillin resistant Staphylococcus aureus (MRSA). Our results therefore refute the current notion on the ecological role of the facultative marine fungi and implicate that in the current context of global climate change and severe weather events that can result in drastic drops in salinity of coastal waters and redistribution of marine microbes to habitats that support fungal growth, the bioactive potential of these fungi need to be thoroughly investigated.

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