Ultrastructural characterization of stable L-form cells from Erysipelothrix rhusiopathiae and of accompanying artifacts.

The stable L-form of Erysipelothrix rhusiopathiae is a typical protoplast type L-form. Cells are surrounded by a trilamellar cytoplasmic membrane only. They grow in form of aggregations in liquid media and their diameters vary between 0.1 and 2 micrometer. Always a large portion of cells undergoes lysis. It seems to be characteristic for L-form cultures of E. rhusiopathiae that always many artifact structures are formed. The artifacts are spherical particles with diameters of 0.1 micrometer to more than 3 micrometer. They can be differentiated from L-form cells only by electron microscopy. The artifacts consist of electron dense amorphous material and their surface is irregular without a clear boundary line. Obviously, these artifacts are produced from protein components of the medium and from cytoplasmatic components of the lysing L-form cells.