Related Experiment Video
Updated: Aug 18, 2026
In Situ Detection of Bacteria within Paraffin-embedded Tissues Using a Digoxin-labeled DNA Probe Targeting 16S rRNA
Published on: May 21, 2015
Isolation and characterization of a plasmid DNA from periodontopathogenic bacterium, Eikenella corrodens 1073, which
Hiroyuki Azakami1, Hiromi Akimichi, Masakatsu Usui
1Department of Biological Chemistry, Yamaguchi University, Japan. azakami@yamaguchi-u.ac.jp
Abstract:
Eikenella corrodens (Ec) is one of a group of periodontopathogenic bacteria. A plasmid DNA (8.7 kb) isolated from Ec 1073 was designated pMU1. Agarose gel electrophoresis and Southern analysis suggested that pMU1-like plasmids were carried in 2 Ec strains, including 1073, with higher hemagglutination (HA) activity than other strains. We determined the nucleotide sequence of this plasmid and identified 7 ORFs. A homology search revealed that 4 ORFs of pMU1 were homologous to ORFs in pJTPS1, found in a spontaneous avirulent mutant of the phytopathogenic bacterium, Ralstonia solanacearum. pJTPS1 is a putative hypovirulent plasmid, which is thought to control the virulence of R. solanacearum. We also found the ORF to be homologous to the recombinase specific to the type IV pilin gene. We introduced a part of pMU1 into the Ec 23834 strain, which has a pilus structure on its cell surface and forms corroding colonies on solid medium. No pilus structure was observed on the surface of transformants, most of which formed non-corroding colonies. When such transformants (or Ec 1073) were cured of pMU1 with acridine orange, they remained non-foliated and non-corroding. The results suggest that pMU1 might irreversibly affect pilus formation and colony morphology, and might be involved in the pathogenicity and virulence of Ec.
Insights
The Eikenella corrodens plasmid pMU1 may irreversibly impact pilus formation and colony morphology. This suggests pMU1 plays a role in the pathogenicity and virulence of this periodontopathogenic bacterium.
Area of Science:
- Microbiology
- Bacterial Genetics
- Molecular Biology
Background:
- Eikenella corrodens (Ec) is a periodontopathogenic bacterium.
- Plasmids are known to influence bacterial virulence and morphology.
Purpose of the Study:
- To investigate the role of the plasmid pMU1 from Eikenella corrodens in bacterial pathogenicity and virulence.
- To determine the genetic elements and functions encoded by the pMU1 plasmid.
Main Methods:
- Plasmid DNA isolation and characterization (agarose gel electrophoresis, Southern analysis).
- Nucleotide sequencing of the pMU1 plasmid and ORF identification.
- Homology searches against known plasmid sequences.
- Genetic manipulation of Ec strains by introducing pMU1 fragments.
- Phenotypic analysis of transformants (pilus structure, colony morphology, hemagglutination activity).
- Curing of plasmid DNA using acridine orange.
Main Results:
- A 8.7 kb plasmid, pMU1, was isolated from Ec 1073 and found in other high hemagglutination (HA) activity strains.
- Sequence analysis revealed 7 ORFs, with 4 homologous to those in Ralstonia solanacearum's hypovirulent plasmid pJTPS1.
- One ORF showed homology to a type IV pilin gene recombinase.
- Introduction of pMU1 fragments into Ec 23834 abolished pilus formation and resulted in non-corroding colonies.
- Plasmid curing experiments indicated an irreversible effect of pMU1 on pilus formation and colony morphology.
Conclusions:
- The pMU1 plasmid appears to be involved in the pathogenicity and virulence of Eikenella corrodens.
- pMU1 may irreversibly affect pilus formation and colony morphology in Ec.
- The findings provide insights into the genetic basis of Ec virulence and potential therapeutic targets.
