Analysis of Large Deletions and Characterization of the Deletion Endpoints Associated with an Amplifiable DNA Region in Streptomyces Lividans

Abstract

The phenomenon, that Streptomyces species can lose spontaneously certain phenotypes at frequenzies between 10–3 and 10–1 has been recognized since at least 1913 (Beijerinck 1913). This genetic instability is very common in many Streptomyces species and can affect a variety of genes; however, only specific genes are affected in any one strain (reviewed by Cullum et al., 1986; Hutter and Eckhardt, 1988). Frequently antibiotic producing strains, including some of commercial importance, are subject to genetic instability: they lose the ability to produce antibiotics (e.g. tetracyclines), i.e. they “degenerate”. As plasmid-curing agents such as acriflavine and ethidium bromide or UV-irradiation increased the frequency of mutation drastically, several authors suggested that the loss of a plasmid caused the loss of antibiotic production and they concluded that genes (or regulatory genes) for antibiotic production are coded on plasmids.