8
D. E. MAHONY
bacteriocin produced by strain 28. The degree of bacterial inhibition was
dependent on the concentration of the bacteriocin, and the growth phase of
the indicator. There was an apparent lag in action when the bacteriocin
was added to a young 30 min culture, but when the bacteriocin was added
to a culture at 120 min or later, growth was halted much more quickly.
Broth cultures treated with bacteriocin continued to produce gas, although
there was marked inhibition of growth as measured by viable count and
optical density. There was no complete clearing of the treated culture.
Bacteriocin 28 appears to act on sensitive indicator strains of C. perfringens
through inhibition of cell wall synthesis or removal of the pre-existing cell
wall. This is suggested by the development of spheroplasts from bacteriocin-treated cells in liquid media, and of L-form-type colonies on solid
media (Mahony et al., 1971). Other bacteriocins which we have studied
inhibit protein, DNA or RNA synthesis or a combination thereof (Mahony,
unpublished data).
In studying the mode of action of their lytic type of bacteriocin, Hirano
and Imamura (1972a, c) compared it to that of lysozyme, since the lytic factor
caused a loss of the Gram-staining property and disintegration of sensitive
cells. However, it differed from lysozyme in being active only on strains of
C. perfringens and not on any other Gram-positive species tested. Both living
and dead cells were affected by the bacteriocin with cells killed by chloroform
treatment lysing more rapidly, possibly due to loss of some protective
mechanism found on the outside of the cell wall of the living bacteria.
Clarke et al. (1975) indicated a lytic action of their perfringocin on cells of
C. pasteurianum.
Ionesco and Bouanchaud (1973) and Ionesco et al. (1976) have provided
evidence that bacteriocin production in C. perfringens type A (strain
BP6K-Ns) is controlled by a plasmid with a molecular weight of 5.7 x 106
daltons (Ionesco et al., 1976). Sebald and Ionesco (1974) showed that the
initiation of spore germination in this strain was inhibited by the N5
bacteriocin and subsequently Wolff and Ionesco (1975) purified the bacteriocin by ion exchange and Sephadex chromatography. The protein of
82,000 molecular weight ran as a single band in polyacrylamide gels.
Ionesco and Wolff (1975) describe the mode of action of bacteriocin N5.
Simultaneous inhibition of DNA, RNA and protein synthesis occurred in
sensitive cells treated with this bacteriocin.
To summarise published results to date on the bacteriocins of C. perfringens we may say: some are spontaneously produced while others can
be induced by UV light or Mitomycin C. No bacteriophage-like particles
have been reported with bacteriocin activity. Bacteriocins showing various
host ranges have been demonstrated ; some intraspecies specific ; some
intrageneric ; and others intergeneric. Two of 25 bacteriocins described are
D. E. MAHONY
bacteriocin produced by strain 28. The degree of bacterial inhibition was
dependent on the concentration of the bacteriocin, and the growth phase of
the indicator. There was an apparent lag in action when the bacteriocin
was added to a young 30 min culture, but when the bacteriocin was added
to a culture at 120 min or later, growth was halted much more quickly.
Broth cultures treated with bacteriocin continued to produce gas, although
there was marked inhibition of growth as measured by viable count and
optical density. There was no complete clearing of the treated culture.
Bacteriocin 28 appears to act on sensitive indicator strains of C. perfringens
through inhibition of cell wall synthesis or removal of the pre-existing cell
wall. This is suggested by the development of spheroplasts from bacteriocin-treated cells in liquid media, and of L-form-type colonies on solid
media (Mahony et al., 1971). Other bacteriocins which we have studied
inhibit protein, DNA or RNA synthesis or a combination thereof (Mahony,
unpublished data).
In studying the mode of action of their lytic type of bacteriocin, Hirano
and Imamura (1972a, c) compared it to that of lysozyme, since the lytic factor
caused a loss of the Gram-staining property and disintegration of sensitive
cells. However, it differed from lysozyme in being active only on strains of
C. perfringens and not on any other Gram-positive species tested. Both living
and dead cells were affected by the bacteriocin with cells killed by chloroform
treatment lysing more rapidly, possibly due to loss of some protective
mechanism found on the outside of the cell wall of the living bacteria.
Clarke et al. (1975) indicated a lytic action of their perfringocin on cells of
C. pasteurianum.
Ionesco and Bouanchaud (1973) and Ionesco et al. (1976) have provided
evidence that bacteriocin production in C. perfringens type A (strain
BP6K-Ns) is controlled by a plasmid with a molecular weight of 5.7 x 106
daltons (Ionesco et al., 1976). Sebald and Ionesco (1974) showed that the
initiation of spore germination in this strain was inhibited by the N5
bacteriocin and subsequently Wolff and Ionesco (1975) purified the bacteriocin by ion exchange and Sephadex chromatography. The protein of
82,000 molecular weight ran as a single band in polyacrylamide gels.
Ionesco and Wolff (1975) describe the mode of action of bacteriocin N5.
Simultaneous inhibition of DNA, RNA and protein synthesis occurred in
sensitive cells treated with this bacteriocin.
To summarise published results to date on the bacteriocins of C. perfringens we may say: some are spontaneously produced while others can
be induced by UV light or Mitomycin C. No bacteriophage-like particles
have been reported with bacteriocin activity. Bacteriocins showing various
host ranges have been demonstrated ; some intraspecies specific ; some
intrageneric ; and others intergeneric. Two of 25 bacteriocins described are