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Fine structure of the cell envelope layers of Flexibacter polymorphus
Canadian Journal of Microbiology
|November 1, 1975
Summary
The marine bacterium Flexibacter polymorphus has a unique cell envelope with an outer membrane, inner membrane, and an intermediate layer. Macromolecular
Area of Science:
- Microbiology
- Cell Biology
- Bacterial Ultrastructure
Background:
- Flexibacter polymorphus is a filamentous gliding marine bacterium.
- Understanding bacterial cell envelope structure is crucial for microbiology.
- Previous knowledge on F. polymorphus cell envelope composition was limited.
Purpose of the Study:
- To elucidate the detailed structure of the Flexibacter polymorphus cell envelope using electron microscopy.
- To investigate the arrangement and potential function of surface-associated macromolecular structures.
- To describe the process of cell division and filament formation in F. polymorphus.
Main Methods:
- Transmission electron microscopy (TEM) of intact cells and isolated envelope fragments.
- Lysozyme treatment to induce cell separation and investigate cell wall components.
- Sonication and negative staining for high-resolution analysis of surface structures.
Main Results:
- The cell envelope comprises an outer membrane (lipopolysaccharide), an inner cytoplasmic membrane, and an intermediate electron-dense layer, possibly peptidoglycan.
- A hexagonal array of cup-shaped macromolecular elements ('goblets') is attached to the outer membrane.
- Goblets appear to penetrate the outer membrane, with connections to the intermediate layer or cytoplasmic membrane.
- Cell division involves septum formation, but cells typically fail to separate, remaining enclosed by a common outer membrane.
- Autolysis releases goblet-coated outer membrane vesicles.
Conclusions:
- Flexibacter polymorphus possesses a complex cell envelope with unique surface structures (goblets).
- The arrangement and potential membrane penetration of goblets suggest a role in cell adhesion or interaction.
- The failure of cell separation after division is attributed to the persistent common outer membrane.
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