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Plasmid loss and changes within the chromosomal DNA of Streptomyces reticuli

H Schrempf

    Journal of Bacteriology
    |August 1, 1982
    PubMed

    Insights

    Streptomyces reticuli plasmid DNA influences secondary metabolism and antibiotic resistance. Amplified chromosomal sequences in plasmidless variants suggest complex genetic regulation of these traits.

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Genetics

    Background:

    • The wild-type Streptomyces reticuli strain produces melanin and leucomycin, associated with 48-49 megadalton plasmid DNA.
    • Plasmidless variants exhibit altered secondary metabolism and antibiotic resistance profiles.

    Purpose of the Study:

    • To investigate the role of plasmid DNA and chromosomal alterations in the secondary metabolism and antibiotic resistance of Streptomyces reticuli.
    • To characterize the genetic basis of phenotypic changes in plasmidless variants.

    Main Methods:

    • Colony hybridization technique for streptomycetes.
    • Plasmid DNA transformation and analysis.
    • Chromosomal DNA hybridization studies.

    Main Results:

    • Plasmidless variants showed altered secondary metabolism and antibiotic resistance.
    • Wild-type plasmid DNA transformation was unstable in regenerated mycelium.
    • Plasmidless variants contained amplified chromosomal nucleotide sequences, distinct from ribosomal or plasmid genes.
    • These amplified sequences exhibited homologies and varied in number and size across strains.

    Conclusions:

    • Alterations in secondary metabolism in S. reticuli are linked to changes in both chromosomal and extrachromosomal DNA.
    • Amplified chromosomal sequences in plasmidless variants play a role in phenotypic changes.
    • Further research is needed to elucidate the precise mechanisms of genetic regulation.

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