Using a ‘one strain-many compounds’ (OSMAC) approach to screen a collection of diverse fungi from Aotearoa New Zealand for antibacterial activity againstEscherichia coli

There is an urgent need to identify new chemical compounds with novel modes of action to help manage the antimicrobial resistance crisis. Fungi are prolific producers of secondary metabolites, including those with antimicrobial properties, and contain biosynthetic gene clusters that awaken only under certain growth conditions. In recent years, a wealth of novel fungal biosynthetic pathways and compounds have been identified, suggesting fungi remain a viable source for developing new antimicrobials. The International Collection of Microorganisms from Plants (ICMP) contains thousands of fungi and bacteria primarily sourced from Aotearoa New Zealand. Here, we report the results of our efforts to screen 32 fungal ICMP isolates for activity againstEscherichia coli, a leading cause of deaths attributable to antimicrobial resistance. We used a ‘one strain-many compounds’ (OSMAC) approach, growing the ICMP isolates on seven different media with different pH and various carbon and nitrogen sources. We also tested the isolates for activity at various ages. Our results indicate that several of the tested fungi possess anti-E. coliactivity and are suitable for further study, including the aero-aquatic AscomyceteHyaloscyphasp. ICMP 16864. Our results also provide further strong evidence for the impact of media on both fungal growth and bioactivity.