Antimicrobial activity of the endophytic fungus Neofusicoccum australe

To perform zone of inhibition (ZOI) testing, potato dextrose agar (PDA) plates were inoculated with a lawn of either antibiotic-sensitive Escherichia coli (ATCC 25922) or resistant clinical isolates (CTX-M-9, CTX-M-14, CTX-M-15, NDM-1) or antibiotic-resistant Klebsiella pneumoniae (ATCC 700603). Similarly, Mueller-Hinton agar plates were inoculated with a lawn of either antibiotic-sensitive Staphylococcus aureus (ATCC 29213) or antibiotic-resistant S. aureus (ATCC 33593). Neofusicoccum australe was grown on PDA plates and fungal plugs removed using a 6 mm punch biopsy tool (Catalogue number: SH241, Amtech Medical, New Zealand). Fungal plugs were placed onto the bacterial lawns, alongside PDA plugs containing no fungus. Plates were incubated inverted at 37°C for 24 h before measuring any zones of inhibition (in mm) produced.