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Description of two morphotypes of Peptostreptococcus micros
P J van Dalen1, T J van Steenbergen, M M Cowan
1Department of Oral Microbiology, Academic Centre for Dentistry Amsterdam, The Netherlands.
International Journal of Systematic Bacteriology
|October 1, 1993
Summary
A newly identified rough morphotype of Peptostreptococcus micros, a periodontal pathogen, was discovered alongside the smooth type. Both morphotypes share genetic homology but exhibit distinct surface structures and cell surface properties.
Area of Science:
- Microbiology
- Oral Health
- Periodontology
Background:
- Peptostreptococcus micros is a known oral bacterium implicated in periodontal disease.
- This species is frequently isolated from human abscesses.
- A novel rough morphotype of P. micros was observed in periodontitis plaque samples.
Purpose of the Study:
- To describe and characterize the previously undescribed rough morphotype of P. micros.
- To compare the rough and smooth morphotypes of P. micros.
- To investigate the genetic and phenotypic differences between the two morphotypes.
Main Methods:
- Isolation and culturing of smooth and rough morphotypes.
- DNA-DNA reassociation studies for genetic homology.
- Physiological characterization using API-32A and API-ZYM kits.
- Electron microscopy for cell surface structure analysis.
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) for protein profiling.
- Xylene-water phase partition for cell surface hydrophilicity/hydrophobicity assessment.
Main Results:
- Both smooth and rough morphotypes showed high DNA-DNA homology, confirming they belong to the same species.
- Distinct colony morphologies were observed: smooth (small, dome-shaped, nonhemolytic) and rough (dry, hemolytic, wrinkled edges).
- Rough morphotype cells possessed external fibrillar structures, absent in the smooth morphotype.
- SDS-PAGE profiles differed between morphotypes.
- Smooth morphotype was hydrophobic, while the rough morphotype was relatively hydrophilic.
- Rough morphotype stability was observed on blood agar, but it transitioned to a smooth, nonfibrillar type upon repeated broth subculturing.
Conclusions:
- Peptostreptococcus micros exhibits distinct stable morphotypes (smooth and rough) with significant phenotypic differences.
- The rough morphotype is characterized by fibrillar surface structures and altered cell surface properties.
- These findings contribute to understanding the heterogeneity within P. micros populations and their role in periodontal disease.