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Extrachromosomal deoxyribonucleic acid in R factor-harboring Enterobacteriaceae
Journal of Bacteriology
|February 1, 1976
Summary
This study characterized extrachromosomal deoxyribonucleic acid (DNA) from R factor-harboring Enterobacteriaceae, revealing extensive variability in plasmid DNA physical characteristics. The findings highlight diverse circular DNA molecules and densities within these drug-resistant bacteria.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- R factors confer transferable drug resistance in Enterobacteriaceae.
- Understanding the physical characteristics of R factors is crucial for combating antibiotic resistance.
Purpose of the Study:
- To isolate and characterize extrachromosomal deoxyribonucleic acid (DNA) from R factor-harboring Enterobacteriaceae.
- To investigate the physical properties, including size and density, of plasmid DNA associated with transferable drug resistance.
Main Methods:
- Isolation of extrachromosomal DNA from 24 Enterobacteriaceae strains.
- Characterization using analytical ultracentrifugation and electron microscopy.
- Analysis of R factor patterns and plasmid DNA size and density.
Main Results:
- Extrachromosomal, circular DNA molecules ranging from 0.4 to 52 µm were identified in all strains.
- Multiple size classes of circular DNA were observed in most preparations.
- Buoyant density of extrachromosomal DNA varied between 1.700 and 1.720 g/cm³.
- Three-fourths of R factors were classified as fi+.
Conclusions:
- Significant variability exists in the physical characteristics of plasmid DNA from R factor-harboring strains.
- The findings provide insights into the structural diversity of plasmids mediating drug resistance in Enterobacteriaceae.