Intraclonal polymorphism in the bacterium Streptomyces ambofaciens ATCC23877: evidence for a high degree of heterogeneity of the wild type clones

In Streptomyces ambofaciens a genetic instability generates a high degree o f polymorphism consisting of four main phenotypes: pigmented colonies (Pig( +) qualified as WT phenotype), pigment-defective colonies, pigmented coloni es with pigment-defective sector and pigmented colonies with pigment-defect ive papillae. Molecular analysis of Pig(col)(-) and Pig(sec)(-) (pigment-de fective mutant derived from a colony and a sector, respectively) produced b y genetic instability and isolated in five Pig(+) subclones progenies revea led a new aspect of polymorphism in S. ambofaciens ATCC23877. Frequencies o f Pig(col)(-) and Pig(sec)(-) mutants deleted at the chromosome ends varied from one WT progeny to another. Two main types of deleted mutants were obs erved: deleted for one or both chromosomal extremities. The relative propor tion of these two categories differed according to the WT progeny. These re sults argue for heterogeneity of the WT clones, i.e., Pig(+) colonies, orig inated from S. ambofaciens ATCC23877. (C) 1999 Elsevier Science B.V. All ri ghts reserved.