Streptomyces coelicolor is a soil-dwelling, filamentous bacterium responsible for producing most of the natural antibiotics used in human and veterinary medicine. In May 9 Nature, Stephen Bentley and colleagues from The Wellcome Trust Sanger Institute, Cambridge, UK and the John Innes Centre, Norwich, UK, report the complete genome sequence of the model actinomycete S. coelicolor A3(2).

Bentley et al. used an ordered cosmid library to sequence the S. coelicolor genome. They observed that at 8,667,507 base pairs the linear chromosome of this organism has the largest number of genes so far discovered in a bacterium — 7,825 — many located in 20 gene clusters coding for known or predicted secondary metabolites.

"The genome contains an unprecedented proportion of regulatory genes, predominantly those likely to be involved in responses to external stimuli and stresses, and many duplicated gene sets that may represent 'tissue-specific' isoforms operating in different...