In situ activation and heterologous production of a cryptic lantibiotic from a plant-ant derived Saccharopolyspora species

Abstract Most clinical antibiotics are derived from actinomycete natural products (NPs) discovered at least 60 years ago. Repeated rediscovery of known compounds led the pharmaceutical industry to largely discard microbial NPs as a source of new chemical diversity but advances in genome sequencing revealed that these organisms have the potential to make many more NPs than previously thought. Approaches to unlock NP biosynthesis by genetic manipulation of the strain, by the application of chemical genetics, or by microbial co-cultivation have resulted in the identification of new antibacterial compounds. Concomitantly, intensive exploration of coevolved ecological niches, such as insect-microbe defensive symbioses, has revealed these to be a rich source of chemical novelty. Here we report the novel lanthipeptide antibiotic kyamicin generated through the activation of a cryptic biosynthetic gene cluster identified by genome mining Saccharopolyspora species found in the obligate domatia-dwelling ant Tetraponera penzigi of the ant plant Vachellia drepanolobium. Heterologous production and purification of kyamicin allowed its structural characterisation and bioactivity determination. Our activation strategy was also successful for the expression of lantibiotics from other genera, paving the way for a synthetic heterologous expression platform for the discovery of lanthipeptides that are not detected under laboratory conditions or that are new to nature. Importance The discovery of novel antibiotics to tackle the growing threat of antimicrobial resistance is impeded by difficulties in accessing the full biosynthetic potential of microorganisms. The development of new tools to unlock the biosynthesis of cryptic bacterial natural products will greatly increase the repertoire of natural product scaffolds. Here we report an activation strategy that can be rapidly applied to activate the biosynthesis of cryptic lanthipeptide biosynthetic gene clusters. This allowed the discovery of a new lanthipeptide antibiotic directly from the native host and via heterologous expression.