DNA deletions in spontaneous chloramphenicol-sensitive mutants of Streptomyces coelicolor A 3(2) and Streptomyces lividans 66.

A mutant of Streptomyces coelicolor A 3(2) highly resistant to chloramphenicol was selected. It had amplified some chromosomal DNA fragments to a copy number of 20-50. Some of the amplified fragments were cloned and used as hybridisation probes to investigate the spontaneous chloramphenicol-sensitive mutants which occur at high frequency in this species and the closely related species Streptomyces lividans 66. These investigations demonstrated that chloramphenicol sensitivity in both species is associated with large deletions that are at least 40 kb in length.