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Evidence for a disseminated plasmid in Streptococcus mutans.
Infection and Immunity
|April 1, 1978
Summary
A 3.6-megadalton plasmid is found in about 5% of Streptococcus mutans strains. This common plasmid, present in unique strains, is a disseminated extrachromosomal element in S. mutans.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Naturally occurring strains of Streptococcus mutans are a focus of oral microbiome research.
- Extrachromosomal elements like plasmids can influence bacterial physiology and adaptation.
Purpose of the Study:
- To investigate the presence and characteristics of a specific multicopy plasmid in Streptococcus mutans.
- To determine if this plasmid is a common feature across different S. mutans strains.
Main Methods:
- Survey of 86 Streptococcus mutans isolates to identify plasmid presence.
- Analysis of plasmid deoxyribonucleic acid (DNA) quantity relative to chromosomal DNA.
- Restriction endonuclease digestion to characterize plasmid structure.
Main Results:
- Approximately 5% of S. mutans isolates contained a 3.6-megadalton multicopy plasmid.
- Plasmid DNA constituted 2-6% of total DNA per cell, varying by host strain.
- Restriction enzyme analysis revealed identical digestion patterns for the plasmid across four different strains, indicating a conserved structure.
Conclusions:
- The 3.6-megadalton plasmid is a disseminated extrachromosomal element in Streptococcus mutans.
- Despite occurring in physiologically unique strains, the plasmid's conserved structure suggests widespread distribution.