Optical mesoscopy of Streptomyces

The antimicrobial resistance crisis is currently one of the biggest threats to global human health. No new chemical classes of antibiotic have been brought to market in over twenty years and with the current trends in antimicrobial resistance, new approaches to natural product discovery must be explored. Around two-thirds of the antimicrobial compounds currently on the market are produced by the genus Streptomyces, a Gram-positive soil dwelling organism with a complex life cycle. Genomic studies have shown that Streptomyces have around thirty biosynthetic gene clusters that have the potential to produce specialised metabolites but few are expressed in laboratory culture. Here we will work to understand how antimicrobial compounds are used as a means of recognising kin and non-kin genotypes in mixed cultures of isogenic strains - this type of recognition has not previously been observed in Streptomyces. It has been postulated since Darwin that competition is often most intense between closely related species, and we hypothesise that this competition has been a driving factor in the evolution of a diverse range of biosynthetic gene clusters in streptomycetes. We hypothesise that competition between closely related genotypes will lead to the upregulation of previously silent biosynthetic gene clusters, potentially leading to the exploitation of previously untapped antimicrobial compounds. In order to create competitive conditions to test this hypothesis, we will develop novel methods of co-culture for the constructed isogenic strains. Moreover, we will observe competition optically using the Mesolens, a new giant lens developed by Prof McConnell and others. This system is capable of observing a volume of over 100mm3 with subcellular resolution. This unique combination of large volume of capture and high resolution will give previously unseen insight to the morphology of Streptomyces through the use of natively expressed fluorescent proteins. We will achieve this through the use of widefield and confocal mesoscopic imaging. Current imaging techniques are unable to study this genus with great detail due to the unique morphology and large colony size. By developing new imaging techniques using the Mesolens we aim to overcome this issue and give unprecedented insight to this complex organism that is not possible with current commercially available microscopes.