Archives of Microbiology

, Volume 113, Issue 3, pp 197–204

Dorsal-ventral differentiation in Simonsiella and other aspects of its morphology and ultrastructure

  • Jack Pangborn
  • Daisy A. Kuhn
  • Janie R. Woods

DOI: 10.1007/BF00492025

Cite this article as:
Pangborn, J., Kuhn, D.A. & Woods, J.R. Arch. Microbiol. (1977) 113: 197. doi:10.1007/BF00492025


The morphology and ultrastructure of the aerobic, Gram-negative multicellular-filamentous bacteria of the genus Simonsiella were investigated by scanning and transmission electron microscopy. The flat, ribbon-shaped, multicellular filaments show dorsal-ventral differentiation with respect to their orientations to solid substrata. The dorsal surface, orientated away from the substrate, is convex and possesses an unstructured capsule. The ventral surface, on which the organisms adhere and glide, is concave and has an extracellular layer with fibrils extending at right angles from the cell wall. The cytoplasm in the ventral region contains a proliferation of intracytoplasmic membranes and few ribosomes in comparison to the cytoplasm in other parts of the cell. Centripetal cell wall formation is asymmetrical and commences preferentially in the ventral region. Quantitative differences in morphology and cytology exist among selected Simonsiella strains. Functional aspects of this dorsalventral differentiation are discussed with respect to the colonization and adherence of Simonsiella to mucosal squamous epithelial cells in its ecological habitat, the oral cavities of warm-blooded vertebrates.

Key words

Gliding bacterium Simonsiella Oral cavity Electron microscopy Morphology Dorsal-ventral differentiation Ultrastructure 

List of Abbreviations


scanning electron microscope


transmission electron microscope

Copyright information

© Springer-Verlag 1977

Authors and Affiliations

  • Jack Pangborn
    • 1
  • Daisy A. Kuhn
    • 2
  • Janie R. Woods
    • 1
  1. 1.Facility for Advanced InstrumentationUniversity of CaliforniaDavisUSA
  2. 2.Department of BiologyCalifornia State UniversityNorthridgeUSA

Personalised recommendations