Using CRISPR/Cas9 genome editing to facilitate antibiotic discovery in novel Streptomyces species

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Antibiotics are some of our most important medicines; they treat a range of infectious diseases and are also used to prevent infections in immunocompromised patients such as those undergoing chemotherapy or organ transplant surgery. Unfortunately, microorganisms are increasingly developing resistance to our current antibiotics, meaning the antibiotics no longer work as effectively. New antibiotics that have activity against resistant microorganisms are urgently needed. Around two-thirds of currently used antibiotics were developed from compounds made naturally by soil-dwelling bacteria like Streptomyces. Streptomyces are thought to produce many antimicrobial compounds in the environment, but in the lab, they only usually make a few. This means many more antimicrobial molecules remain to be discovered from Streptomyces if we can find ways to switch on these 'silent' pathways in the lab.This project will use genetic engineering to switch on the production of antibiotics in Streptomyces formicae, a new strain isolated from the nests of Tetraponera penzigi plant-ants. S. formicae is a talented strain, with the potential to produce many antimicrobial molecules. So far, only one has been characterised; a new family of antibiotics called the formicamycins which are potent inhibitors of resistant microorganisms. By deleting the genes responsible for formicamycin production, we have shown that S. formicae starts to produce previously 'silent' compounds, including more new antimicrobials that have activity against resistant microorganisms. In this fellowship, I will seek to characterise these new antimicrobials and determine their clinical potential. I also aim to understand how the antimicrobial molecules are made by S. formicae and why deletion of the formicamycin pathway induces the production of these previously silent molecules. By understanding how these silent pathways are switched on, we can determine whether the same approach could be used in the many hundreds of other Streptomyces strains isolated across the globe, facilitating the discovery of many new antimicrobial molecules.