32
H. P. R. SEELIGER AND I<. HOHNE
by immune electron microscopy, Smith and Metzger (1962) demonstrated a
capsule-like structure on L. monocytogenes surrounding the bacterial cell
continuously in a regular size and shape. By histochemical stain techniques
this structure was found to consist of mucopolysaccharide material. These
“capsules” were demonstrated after cultivating organisms on media
enriched with serum and glucose (Smith and Metzger, 1962). The existence
of true capsules could, however, not be demonstrated by Seeliger and
Bockemuhl (1968).
All strains of L. monocytogenes hitherto isolated from natural sources have
been motile (Seeliger, 1961) in contrast to all species of Erysipelothrix and
most corynebacteria. Leifson and Palen (1955) stated after investigating
81 stock strains of L. monocytogenes that the flagellar arrangement is
always peritrichous with at most 4 flagella.
11. CHEMICAL COMPOSITION
A protein substance on the surface of L. monocytogenes has been demonstrated (Osebold et ul., 1965) by trypsinisation which increased the serologic sensitivity and explained the inagglutinability of some somatic
antigens. The material released showed an ultraviolet absorption peak at
200 nm and gave a spot on paper chromatograms compatible with polypeptide.
The cell walls of Listeriu contain about 20% hexose (glucose and
galactose), 5% hexosamine and 5% protein with alanine, glutamic acid,
diaminopimelic acid, aspartic acid as well as leucine and are easily broken
up by mechanical disintegration. Shaking the cells with glass beads longer
than 4 h extensively damages the cell walls. I n comparison with other
Gram-positive organisms listeriae are also more sensitive to trypsin and
nucleases. Roots (1958) obtained homogeneous cell wall preparations after
an initial extraction followed by 4 h agitation with glass beads and subsequent enzymatic treatment with trypsin, ribonuclease and deoxyribonuclease. It was concluded that the cell walls of Listeriu contain great
quantities of material specific for the enzymes employed.
All Listeriu strains freshly isolated from pathological material are capable
of lysing red blood cells from most mammalian animals (cf. Seeliger,
1961a; Gray and Killinger, 1966). Certain strains show a pronounced
/3-haemolysis on sheep blood agar plates thereby producing wide halos.
The haemolysing activity is most regularly demonstrated using horse
blood. Lysis of the red blood cells is effected by a filtrable haemolysin
which is also produced in blood-free substrates and which acts on erythrocytes after passage through bacteria-proof filters.
H. P. R. SEELIGER AND I<. HOHNE
by immune electron microscopy, Smith and Metzger (1962) demonstrated a
capsule-like structure on L. monocytogenes surrounding the bacterial cell
continuously in a regular size and shape. By histochemical stain techniques
this structure was found to consist of mucopolysaccharide material. These
“capsules” were demonstrated after cultivating organisms on media
enriched with serum and glucose (Smith and Metzger, 1962). The existence
of true capsules could, however, not be demonstrated by Seeliger and
Bockemuhl (1968).
All strains of L. monocytogenes hitherto isolated from natural sources have
been motile (Seeliger, 1961) in contrast to all species of Erysipelothrix and
most corynebacteria. Leifson and Palen (1955) stated after investigating
81 stock strains of L. monocytogenes that the flagellar arrangement is
always peritrichous with at most 4 flagella.
11. CHEMICAL COMPOSITION
A protein substance on the surface of L. monocytogenes has been demonstrated (Osebold et ul., 1965) by trypsinisation which increased the serologic sensitivity and explained the inagglutinability of some somatic
antigens. The material released showed an ultraviolet absorption peak at
200 nm and gave a spot on paper chromatograms compatible with polypeptide.
The cell walls of Listeriu contain about 20% hexose (glucose and
galactose), 5% hexosamine and 5% protein with alanine, glutamic acid,
diaminopimelic acid, aspartic acid as well as leucine and are easily broken
up by mechanical disintegration. Shaking the cells with glass beads longer
than 4 h extensively damages the cell walls. I n comparison with other
Gram-positive organisms listeriae are also more sensitive to trypsin and
nucleases. Roots (1958) obtained homogeneous cell wall preparations after
an initial extraction followed by 4 h agitation with glass beads and subsequent enzymatic treatment with trypsin, ribonuclease and deoxyribonuclease. It was concluded that the cell walls of Listeriu contain great
quantities of material specific for the enzymes employed.
All Listeriu strains freshly isolated from pathological material are capable
of lysing red blood cells from most mammalian animals (cf. Seeliger,
1961a; Gray and Killinger, 1966). Certain strains show a pronounced
/3-haemolysis on sheep blood agar plates thereby producing wide halos.
The haemolysing activity is most regularly demonstrated using horse
blood. Lysis of the red blood cells is effected by a filtrable haemolysin
which is also produced in blood-free substrates and which acts on erythrocytes after passage through bacteria-proof filters.