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Genetic transformation of Streptococcus pneumoniae by heterologous plasmid deoxyribonucleic acid

F Barany, A Tomasz

    Journal of Bacteriology
    |November 1, 1980
    PubMed

    Insights

    Genetic transformation successfully introduced antibiotic resistance plasmids into Streptococcus pneumoniae. This process required specific cellular conditions and demonstrated effectiveness even with altered plasmid DNA structures.

    Area of Science:

    • Microbiology
    • Molecular Biology
    • Genetics

    Background:

    • Antibiotic resistance is a growing public health concern.
    • Understanding gene transfer mechanisms in bacteria is crucial for combating resistance.
    • Streptococcus pneumoniae is a significant human pathogen.

    Purpose of the Study:

    • To investigate the efficiency and requirements of introducing heterologous plasmid deoxyribonucleic acids (DNAs) into Streptococcus pneumoniae.
    • To characterize the properties of transformed plasmid DNA within the bacterial host.
    • To explore the impact of DNA structure on transformation efficiency.

    Main Methods:

    • Genetic transformation of Streptococcus pneumoniae with various antibiotic resistance plasmids.
    • Competence assays and competition experiments with chromosomal DNA.
    • Analysis of reisolated plasmid DNA using agarose gel electrophoresis and restriction enzyme digestion.
    • Assessment of transforming activity associated with different plasmid DNA forms (monomers, multimers, linearized).

    Main Results:

    • High transformation frequencies were observed for multiple antibiotic resistance plasmids (erythromycin, tylosin, lincomycin, tetracycline, chloramphenicol).
    • Transformation efficiency was dependent on bacterial competence and DNA concentration, with saturation observed.
    • A defective endonuclease mutant strain failed to undergo plasmid transformation.
    • Reisolated plasmids retained their structural integrity and transforming activity.
    • Linearized plasmid DNA also exhibited transforming activity, an unexpected finding.

    Conclusions:

    • Heterologous plasmid DNA can be efficiently introduced into Streptococcus pneumoniae via genetic transformation.
    • The process is dependent on specific physiological conditions and bacterial factors.
    • Plasmid DNA integrity is maintained post-transformation, and even linearized forms can mediate gene transfer.
    • These findings contribute to understanding horizontal gene transfer mechanisms in bacteria.

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