Interspecies modulation of bacterial development through iron competition and siderophore piracy

Abstract

Summary: While soil‐dwelling actinomycetes are renowned for secreting natural products, little is known about the roles of these molecules in mediating actinomycete interactions. In a previous co‐culture screen, we found that one actinomycete, A mycolatopsis sp. AA 4, inhibited aerial hyphae formation in adjacent colonies of S treptomyces coelicolor. A siderophore, amychelin, mediated this developmental arrest. Here we present genetic evidence that confirms the role of the amc locus in the production of amychelin and in the inhibition of S. coelicolor development. We further characterize the A mycolatopsis sp. AA 4 – S. coelicolor interaction by examining expression of developmental and iron acquisition genes over time in co‐culture. Manipulation of iron availability and/or growth near A mycolatopsis sp. AA 4 led to alterations in expression of the critical developmental gene bldN, and other key downstream genes in the S. coelicolor transcriptional cascade. In A mycolatopsis sp. AA 4, siderophore genes were downregulated when grown near S. coelicolor, leading us to find that deferrioxamine E, produced by S. coelicolor, could be readily utilized by A mycolatopsis sp. AA 4. Collectively these results suggest that competition for iron via siderophore piracy and species‐specific siderophores can alter patterns of gene expression and morphological differentiation during actinomycete interactions.