Whole-genome sequencing of the Streptomyces coelicolor bldA39 mutant (J1700) reveals hundreds of previously unknown mutations.

We report the genome sequence of the bldA39 (J1700) mutant of Streptomyces coelicolor, a historically important strain that is deficient in sporulation and antimicrobial production. The S. coelicolor J1700 strain was used extensively from the 1980s onwards to underpin important discoveries in development and antibiotic production in Streptomyces. The bldA gene encodes a leucyl tRNA, required for the translation of the rare TTA codon found in ~2% of genes in Streptomyces. The whole genome of S. coelicolor J1700 was obtained via Illumina sequencing and mapped to the S. coelicolor M145 reference genome. Analysis of the genome sequence compared to S. coelicolor M145 identified the known bldA39 mutation (T>C) and revealed more than 300 further mutations, likely associated with the S. coelicolor J1501 genetic background the strain was created in, including the nature of the hisA1 and uraA1 alleles used extensively in genetic mapping experiments and several mutations in natural product biosynthetic gene clusters. This work highlights the importance of whole-genome sequencing of historically important strains.