MULTIPLICATION OF DNA FRAGMENTS IN STREPTOMYCES ANTIBIOTICUS PRODUCING OLEANDOMYCIN

  • 1 January 1983
    • journal article
    • research article
    • Vol. 28  (3) , 163-167
Abstract
Two strains of S. antibioticus producing oleandomycin were studied. Strain 326 was obtained from the initial laboratory strain and strain 1607 from strain 326 as a result of multistage selection aimed at increasing the antibiotic production capacity. Extra chromosomal ring DNA could be identified in strain 1607. The identified DNA was designated as eSA1 or extrachromosomal element of S. antiobiticus 1. The MW of this DNA is 21.3 Md [megadaltons]. It is represented by 1 copy/chromosome. No eSA1 was isolated from strain 326 at CsCl-EtBr gradient. Hybridization studies according to Southern with the use as a probe of 32-eSA1 DNA showed that strain 326 contained 1 copy of eSA1/chromosome in the integrated state. The hybridization studies, EM and analysis of the total DNA in CsCl-EtBr gradient showed that eSA1 in strain 1607 was tandemly multireplicated in the chromosome content. In the autonomous state its number was approximately equal to 1 copy/chromosome. The presence of eSA1 in strain 1607 in the autonomous state probably results from its segregation during homologous recombination due to tandem multireplication. The data are indicative of multiplication in strain 1607 of the chromosome fragment 23.3 Md in size. It is suggested that an increase in the oleandomycin production capacity of strain 1607 is associated with multiplication of the DNA fragment (eSA1) containing the genes determining production of the antibiotic.