Peptidoglycan .Types of Bacterial Cell Walls and their Taxonomic ...

446
depicted in Fig. 24b. The interpeptide bridge
consists of fl-D-Asp-L-Ala.
Strain ATCC 11859, called B. pasteurii,
shows the same peptidoglycan type as B.
sphaericus and is most likely a urease-producing
B. sphaericus. A third strain (own isolate)
contains a fl-DAsp-L-Ser interpeptide bridge.
Some of the L-Ser residues are replaced by
L-Ala. Although more strains of both species
need to be investigated, the peptidoglycan
type is most likely a good criterion to distinguish
B. pasteurii from B. sphaericus.
Genus Clostridium. The cell wall composition
of these anaerobic spore-forming organisms
of the genus Clostridium was studied primarily
by Cummins and co-workers (61, 73, 77). They
determined qualitatively the sugar and amino
acid composition of the cell walls of various
clostridia. There are also a few studies on the
quantitative amino acid composition (221, 296,
376). All the available data on the amino acid
composition of the cell walls of clostridia are
compiled in Table 30.
Most of the species investigated contain only
m-Dpm, Ala, and Glu. Unpublished studies
from our laboratory on cell walls of C. butyricum
have shown that the peptidoglycan of this
organism belongs to the directly cross-linked,
m-Dpm-containing type (Aly). The other m-
Dpm-containing peptidoglycans of the genus
Clostridium presumably show the same type.
Four different species reveal (instead of m-
Dpm) L, L-Dpm and, in addition, Gly in their
cell walls. The primary structure of the peptidoglycan
of C. perfringens was established by
Leyh-Bouille et al. (221). This species shows
the same peptidoglycan type as that described
before for Propionibacterium petersonii and
some Streptomyces sp. (Fig. 15a). The three
other species C. fallax, C. pectinovorum, and C.
pseudofallax probably belong to the same type.
The species C. innocuum, C. paraputrificum,
and C. tertium contain L-Lys instead of Dpm
in their vegetative cell walls. Since no detailed
studies are available, the peptidoglycan type of
these species is unknown. C. innocuum has
probably been misclassified in the genus Clostridium,
since it differs not only in the amino
acid composition of its cell walls but also in its
GC content (43%) from the other strains of
clostridia (GC content, 22-28%) (77).
The status of the other clostridia which
contain no Dpm is uncertain despite their
rather low GC content (24-27%) which is in
good agreement with that of the other members
of the genus clostridia. Further studies are
necessary to clarify the taxonomic position of
these organisms.
SCHLEIFER ANJD
KANDLER BACTERIOL REV.
The peptidoglycans within the genus Clostridium,
as in the genus Bacillus, are rather
uniform. Most of the clostridia contain the
directly cross-linked m-Dpm peptidoglycan
type (variation Aly), but a few species are
distinguished by the occurrence of the
L, L-Dpm-Gly type. The occurrence of other
peptidoglycan types in strains called Clostridium
can be taken as an indication that these
organisms may be improperly classified.
The determination of the structure of the
polysaccharides of the cell walls of clostridia
may be a useful tool for characterization of
species and infraspecific taxa within the genus.
Cummins and Johnson (77) had already
achieved some separation by means of a qualitative
determination of the sugar composition
in the cell walls.
Family Corynebacteriaceae. The family
Corynebacteriaceae is characterized by irregular
rod-shaped cells which usually occur in
angular or palisade formation due to snapping
division. Moreover, a marked diversity in morphology
and a vegetative life cycle are often
found. According to the 7th edition of Bergey's
Manual (49), the family Corynebacteriaceae
comprises six different genera: Corynebacterium,
Arthrobacter, Microbacterium, Cellulomonas,
Listeria, and Erysipelothrix. More
recent studies have shown that almost all of the
organisms included in the family Brevibacteriaceae
are also typical coryneform bacteria
(161, 264, 332; Cziharz, Diplom Thesis, Technical
University, Munich, 1969). Therefore, the
organisms classified in the family Brevibacteriaceae
(genera Brevibacterium and Kurthia)
will be discussed together with the Corynebacteriaceae.
The lack of proper criteria for differentiation
makes the classification of most of the coryneform
organisms rather unsatisfactory. In the
-G-M-G-
L- Ala
D-Glu NH2
I Y E T
L-Lys e D-Asp - a
4 - E L-Ala--- D-Asp- b
D- Ala
D-Ata
I L-Lys
FIG. 24. Fragments of the primary structures of
uncommon peptidoglycans in the genus Bacillus. (a)
L-Lys-D-Asp, B. sphaericus; (b) L-Lys-L-Ala-D-Asp,
B. pasteurii.
I
Downloaded from
http://mmbr.asm.org/
on December 3, 2012 by guest