Future directions for the discovery of antibiotics from actinomycete bacteria.

Antimicrobial resistance (AMR) is a growing societal problem, and without new anti-infective drugs, the UK government-commissioned O'Neil report has predicted that infectious disease will claim the lives of an additional 10 million people a year worldwide by 2050. Almost all the antibiotics currently in clinical use are derived from the secondary metabolites of a group of filamentous soil bacteria called actinomycetes, most notably in the genus Streptomyces. Unfortunately, the discovery of these strains and their natural products (NPs) peaked in the 1950s and was then largely abandoned, partly due to the repeated rediscovery of known strains and compounds. Attention turned instead to rational target-based drug design, but this was largely unsuccessful and few new antibiotics have made it to clinic in the last 60 years. In the early 2000s, however, genome sequencing of the first Streptomyces species reinvigorated interest in NP discovery because it revealed the presence of numerous cryptic NP biosynthetic gene clusters that are not expressed in the laboratory. Here, we describe how the use of new technologies, including improved culture-dependent and -independent techniques, combined with searching underexplored environments, promises to identify a new generation of NP antibiotics from actinomycete bacteria.