Isolation and characterization of plasmid DMA from Bacteroides strains isolated from the human oral cavity

A total of 134 Bacteroides strains isolated from the human oral cavity were examined for plasmid content. Plasmid DNA was isolated from 7 strains of black‐pigmented Bacteroides, including Bacteroides levii strains ATCC 29147 and JP2. All isolated Bacteroides plasmid DNA had a molecular mass of 5.9 M daltons and showed the same electrophoretic pattern when treated with restriction endonuclease. No positive correlation was found between plasmid DNA content and antibiotic resistance, bacteroiocinogenic activity or hemagglutinating activity.