Abstract:
Antibiotic resistance has become a global public health threat and current action plans in place worldwide are mainly focused on preventing the development of resistance to current antibiotics. The discovery of novel antibiotic classes is crucial to solve this crisis. In this project, I have explored New Zealand fungi as a potential source of new antibiotic. New Zealand has a very isolated geography in the world and is home to many unique species, including flightless birds like the kiwi. I hypothesise that New Zealand may also be home to fungal species producing unknown secondary metabolites with antibiotic properties. As standard pure culture techniques may not trigger the production of such secondary metabolites, I have co-cultured fungal isolates with three bacterial species (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa) to encourage competition during growth to increase the probability of locating an antimicrobial compound. I have also used bioluminescently-tagged bacteria, so that I can use bacterial light production as a surrogate for bacterial viability. Reduction in bioluminescence indicates inhibitory activity from the fungi as dead or metabolically inactive bacteria no longer produce light. I complemented this assay by also testing fungal isolates for the ability to produce zones of inhibition when grown with the bacteria. Of the 143 fungal isolates I have screened in triplicates, I have identified 37 with activity against S. aureus, 5 with activity against E. coli, and 6 with activity against P. aeruginosa. I prepared extracts using reverse chromatography from 12 of the fungal isolates that affected light production and showed excellent bacterial inhibition in the zone of inhibition tests. Overall, I did not discover any new types of antibiotics over the course of my project. However, my results show that our screening method is effective and can facilitate the future discovery of novel antibiotics from New Zealand fungi.