Archives of Microbiology

, Volume 145, Issue 2, pp 126–135

Physiology and ultrastructure of Leptothrix discophora SS-1

  • Lee F. Adams
  • William C. Ghiorse
Original Papers

DOI: 10.1007/BF00446769

Cite this article as:
Adams, L.F. & Ghiorse, W.C. Arch. Microbiol. (1986) 145: 126. doi:10.1007/BF00446769

Abstract

Leptothrix discophora strain SS-1 (ATCC 43182) is a Gram-negative, Mn2+-oxidizing, aerobic heterotroph which lost its sheath-forming ability after 18 months of cultivation on laboratory media. SS-1 possesses high 6-phosphogluconate dehydratase and KDPG aldolase activities, and a very low level of phosphofructokinase, indicating carbohydrate catabolism by the Entner-Doudoroff pathway. The strain is polarly flagellated, accumulates PHB up to 67% of its dry weight when grown in pyruvate-containing medium, and has a G+C content of 69.8 mol%. These properties indicate that L. discophora is essentially a pseudomonad which can form a sheath and oxidize Mn2+. Ultrastructural observations made before SS-1 lost its sheath-forming ability indicated two cell types. Short, flagellated, non-sheathed cells seen under the electron microscope probably corresponded to swarmer cells observed under phase-contrast microscopy. These cells contained plate organelles and PHB granules, and produced extracellular blebs approx. 25–50 nm in diameter. Larger sheathed cells also contained plate organelles, PHB granules, and blebs that were often sandwiched between the outer membrane and the sheath. Cells grown in the presence of added Mn2+ were surrounded by an extensive fibrillar matrix, rendered electron dense by precipitation of manganic oxide. The matrix was connected to various points of the cell by outer membrane evaginations or electron dense threads. We propose that the outer membrane blebs represent vehicles for excretion of unorganized sheath material and/or Mn2+-oxidizing protein produced by L. discophora.

Key words

Leptothrix discophora Mn2+-oxidation Enter-Doudoroff pathway Plate organelles PHB granules Outer membrane evaginations Blebs Extracellular polymers Fibrillar matrix 

Copyright information

© Springer-Verlag 1986

Authors and Affiliations

  • Lee F. Adams
    • 1
  • William C. Ghiorse
    • 1
  1. 1.Department of MicrobiologyNew York State College of Agriculture and Life Sciences, Cornell UniversityIthacaUSA
  2. 2.Department of Microbiology and Immunology, SC-42University of WashingtonSeattleUSA

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