DNA amplification and an unstable arginine gene in Streptomyces lividans 66

Abstract
Summary Streptomyces lividans 66 produced spontaneous chloramphenicol-sensitive mutants (Cmls) at a frequency of about 1% of spores. The Cmls mutant strains were very unstable, giving Arg- mutants at frequencies of about 25% of spores. All the Arg- mutants had amplified a particular 5.75 kb DNA fragment into tandem repeats of 250–500 copies per chromosome.