Ultrastruktur der stabilen L‐Formen von Escherichia coli B und W 1655 F⁺

Abstract

In broth cultures thp stabje L-forms of E. coli B and TV 1655 F+ grow as spherical elements with diameters of 0.05 , u up to more than 2 p. Particles below 0.3 p in diameter are probably not, able t o propagate. L-form cells, growing in agar media, are highly pleomorph.Ultrathin sections through L-form cells show that there are no ce!l wall structures. The cells are always surrounded only by the cytoplasmic membrane. Therefore, the L-forms of the two E. coli strains under study may be designa+ed as stable L-forms of the protophst type-UnIike normal rods t h e nucleoids of L-form cells are not marked off clearly from the cytoplasm. There are often vacuoles in the elements, which are surrounded by a typically triple layered membrane. The cytoplasmic membrane may produce local outgrowths of different size. Frequently, intracellular membranes are present in L-form cells. They may be seen as triple layered unit membranes or as st.ructures with 5 and more lagers. With il centre to centre distance of the dark layers of 41 A they are similar t o myelin structures.The quintuple layered structures, which can be found also extracellular, are probably produced by a close contact between the cytoplasmic membrane and the membrane of vacuoles. Formation and function of the intracellular membranes are discussed.Wabxend der Iet,zten Jahre konnten wir mittels Penicillin stabile L-Formen einiger E. coli-Starnme gewinnen (TAUBENECK u. SCHUHMANN 1966, SCHUHMANN u. TAUBENECK 1969. Die L-Form-Stamme wachsen als pleomorphe Zellen in Agarnahrboden oder als kugelige Elemente unterschiedlicher Grofie in fliissigen Medien. Im folgenden wird anhand von zwei Stammen iiber die Ultrastruktur dieser stabilen L-Formen berichtet. Material und MethodenOrganismen: Zunachst wurden die stabilen L-Formen von E. coli B und W 1655 F+ fur die elektronenmikroskopischen Unt,ersuchungen ausgewahlt. Uber Induktion und Ziichtung der stabilen L-Fornien wurde bereits ausfuhrlich berichtet (TAUBENECK u. SCHUHMANN 1966, SCKUHMANN u. TAUBENECR 1969).') Herrn Prof. Dr. H. WARTENBERG zum 70. Gebiirtstag gewidmet. 2'

The analysis of cell division and cell wall synthesis genes reveals mutationally inactivatedftsQandmraYin a protoplast-type L-form ofEscherichia coli

“…Electron microscopical studies have shown spherical cells, lacking the typical components of the Gram‐negative envelope, e.g. flagellae and fimbriae, the OM, the murein layer, and the periplasmic space (Schuhmann & Taubeneck, 1969; Gumpert et al , 1971). The lacking envelope components account for osmotic fragility, for resistance against cell wall‐active antibiotics (e.g.…”

“…The lacking envelope components account for osmotic fragility, for resistance against cell wall‐active antibiotics (e.g. ampicillin), for sensitivity towards inhibitors which cannot pass the OM, for resistance to coliphage infection, and for the inability of the L‐form to mobilize genetic material via conjugation (Schuhmann & Taubeneck, 1969; Gumpert et al , 1971, 2002). Growth of the L‐form is confined to complex media, indicating strict dependency on rich nutrient supply.…”

Theoretical study of lipid biosynthesis in wild‐type Escherichia coli and in a protoplast‐type L‐form using elementary flux mode analysis

“…Interestingly, however, experimental findings have shown that several other bacterial species can grow without a protecting cell wall, and these have been collectively termed ‘stable L‐forms’ [7–9]. Such L‐form mutants are also known from a Gram‐negative E. coli laboratory strain showing no outer membrane structures (strain LW1655F+ [10]), which are typical for this model bacterium [11–13]. In particular, it has remained elusive how E. coli may have been able to shut off the biosynthesis of this essential cell structure.…”