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Site-specific Bacterial Chromosome Engineering: ΦC31 Integrase Mediated Cassette Exchange (IMCE)
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Published on: March 16, 2012

Integration of plasmid DNA coding for beta-lactamase production in the Haemophilus influenzae chromosome

M Murphey-Corb, M Nolan-Willard, R S Daum

    Journal of Bacteriology
    |November 1, 1984
    PubMed

    Insights

    Most beta-lactamase-producing Haemophilus influenzae strains lack plasmids but can transfer this trait. This occurs through chromosomal integration of plasmid DNA, enabling conjugation to recipient strains.

    Area of Science:

    • Microbiology
    • Genetics

    Background:

    • Beta-lactamase production in Haemophilus influenzae confers antibiotic resistance.
    • Extrachromosomal plasmid DNA is often associated with beta-lactamase production.

    Purpose of the Study:

    • To investigate the mechanism of beta-lactamase gene transfer in Haemophilus influenzae strains lacking extrachromosomal DNA.
    • To determine if chromosomal integration plays a role in this transfer.

    Main Methods:

    • Conjugal transfer experiments were performed using beta-lactamase-producing donor strains and a recipient strain.
    • Restriction enzyme analysis was used to examine DNA from donor and recipient strains.
    • Southern transfer hybridization was employed to analyze DNA integration.

    Main Results:

    • 65% of beta-lactamase-producing Haemophilus influenzae strains examined lacked extrachromosomal plasmid DNA.
    • These strains successfully transferred beta-lactamase production to a recipient strain, yielding a 30-megadalton plasmid.
    • Analysis revealed chromosomal integration of plasmid sequences in all donor strains studied.

    Conclusions:

    • Chromosomal integration of plasmid DNA is a mechanism for beta-lactamase gene transfer in Haemophilus influenzae.
    • This integration allows antibiotic resistance traits to be shared even in the absence of extrachromosomal plasmids.

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