Secondary Metabolite Production from Industrially Relevant Bacteria is Enhanced by Organic Nanofibers

Streptomycetes are exploited for the production of a wide range of secondary metabolites, including antibiotics. Therefore, both academic and industrial research efforts are focused on enhancing production of these precious metabolites. So far, this has been mostly achieved by classical or recombinant genetic techniques, in association with process optimization for either submerged or solid state fermentation. New cultivation approaches addressing the natural mycelial growth and life cycle would allow the biosynthetic potential of filamentous strains to be much better exploited. We developed a cultivation system for antibiotic-producing microorganisms which involves electrospun organic nanofibers deposited onto agar plates or immersed in liquid media. Dense filamentous networks of branched hyphae formed by bacterial colonies were found to wrapped around the fibers. We analyzed the effects of fibers on growth and antibiotic production in Streptomyces lividans, and found that the actinorhodin, undecylprodigiosin and calcium dependent antibiotic productions were positively modulated, with a two-to sixfold enhancement compared to standard culture conditions. Highlighting the secondary metabolism-promoting role of nanofibers in bacterial cultures, these results open a route to the design of improved culture systems for microorganisms based on organic nanostructures.