Purification and characterisation of antimicrobial agents isolated from a member of the Paenibacillus genus

Antimicrobial resistance (AMR) poses an ever-increasing threat to public health; the prevalence of resistant bacterial strains has reduced the clinical efficacy of many existing therapeutics and is therefore contributing to rising mortality rates due to difficult to treat bacterial infections. Two key approaches used to mitigate the threat of AMR are the discovery of novel therapeutics with activity against these resistant strains, and educating the wider public about the impact of AMR, and steps that can be taken to reduce the development of resistance. We are combining both approaches to enhance the impact of our public engagement activities. During a recent event at the University of Plymouth, a member of the public isolated the bacterial strain ‘36A’ from the button of a lift control panel. Simultaneous antagonistic screening identified antimicrobial activity against a range of both Gram-positive and Gram-negative bacteria. 36A was then subjected to draft genome sequence determination via the MinION platform (Oxford Nanopore). Growth media were optimised to enhance antimicrobial activity, with fermentation in LB broth and subsequent purification of the culture supernatant via multi-stage column chromatography resulting in the isolation of four putative antimicrobial compounds. Initial characterisation has shown that each compound has a peptidic component, all showing stability and potency at a relatively low concentration against MRSA, E. coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. Structural characterisation has been carried out using mass spectrometry, with further characterisation and cell toxicity studies ongoing. The producing strain has been identified as a member of the Paenibacillus genus.