The emergent properties of streptomyces observed during co-culture and the genomic and morphological characterisation of a Streptomyces lydicus strain

Antimicrobial resistance is one of the biggest global threats to human health in the modern day. No new classes of antibiotics have been approved for clinical use in over 20 years, and so called resistant ‘superbugs’ – such as Pseudomonas aeruginosa are becoming more resistant to even last resort antibiotics. Streptomyces spp. are the most valuable source of antibiotics to date, and genetic analyses has suggested that each strain is capable of producing upwards of thirty secondary metabolites. However, these genes are not all expressed in laboratory monoculture. In this study, four strains of Streptomyces were co-cultured in pairs on five different agar media. It was found that out of 108 conditions, 17 were capable of producing antimicrobial compounds that were bioactive against the ATCC ESKAPE pathogens that neither strain was capable of producing alone. Interestingly, instances of loss of phenotype were also observed, where isolates capable of bioactivity had this activity reversed when in co-culture with another streptomycete. A wild isolate of Streptomyces lydicus was also the subject of genomic and morphological characterisation in this study. Next-Generation Sequencing (NGS) of this strain was carried out using Ion Torrent, and after assembly was composed of 380 scaffolds. AntiSMASH analysis of this strain predicted 27 secondary metabolite gene clusters within the genome. Furthermore, CARD predicted 23 genes associated with antimicrobial resistance. Also presented here is a novel approach to liquid co-culture, in which modified glassware allows for the chemical interactions of two strains across a membrane, while the bacteria themselves are segregated.