Development and Evaluation of a Microbial Natural Product Prefractionation Library

Abstract

Ongoing antibiotic drug discovery is vital as antimicrobial resistance continues to be a significant issue faced in the clinic. Natural products have long been a highly productive source to mine for new antimicrobials. While it has been challenging to discover new and unique antimicrobial natural products, numerous drugs have been derived from studying how natural products function as secondary metabolites. Previous studies suggested that screening natural product extract fraction libraries for antimicrobials can be more productive than screening crude extracts alone. These studies from large industrial enterprises are generally not directly portable to an academic setting due to significant infrastructure costs. We developed a screening platform consisting of low pressure reversed-phase chromatographic separation of methanolic extracts of bacteria and fungi to generate a prefractionated natural product library. This platform is suitable for academic labs to screen for antimicrobial compounds. A large growth inhibitor screen against multiple pathogens and lab strains of microbes was conducted to assess the validity of the advantages of screening fraction libraries versus crude extract libraries and to search for potential new drug-like compounds. Hits were investigated for reproducibility, isolated, and purified. One compound was discovered in an antifungal screen which may be a novel lipopeptide.