The soil-dwelling, filamentous bacteria of the genus Streptomyces are renowned for their production of useful secondary metabolites including antibiotics. The work described in this thesis provides... Show moreThe soil-dwelling, filamentous bacteria of the genus Streptomyces are renowned for their production of useful secondary metabolites including antibiotics. The work described in this thesis provides new insights on the role and regulation of antibiotic production and resistance in these bacteria. It shows that antibiotic resistance is already beneficial at sub-inhibitory antibiotic concentrations. Resistance can even readily evolve at such low concentrations, thereby possibly explaining the level of resistance seen in pristine environments. Antibiotic producers can benefit from spatial structure, as present in the soil, through the preferential allocation of resources and this enables invasion from low frequencies. Streptomyces do not produce all antibiotics continuously, but antibiotic production is instead tightly regulated in response to environmental cues, including those produced by competitors. Streptomyces are most likely to induce antibiotic production in response to a competitor that shares similar secondary metabolite clusters, indicating a possible role for shared signalling. Besides changes in antibiotic production, other responses to competition are revealed on a transcriptomic level, including an increased expression of developmental genes, suggesting earlier sporulation. Show less
