6
D. E. MAHONY
existence of a new third class of welchicin which was active on C. perfringens
and Streptococcus, but not on many strains of the other genera listed
above.
A perfringocin active on C . pasteurianum has been described by Clarke
et al. (1975).
Resistance of the producing strain to its own bacteriocin is a usual
characteristic of bacteriocinogenic organisms, although one of the five
bacteriocins studied by Tubylewicz (1966a), bacteriocin d, was found to be
weakly active against the strain 496 from which it was derived, and one of the
strains reported by Sasarman and Antohi (1968), strain 1241, type E, produced a welchicin A active against all the strains tested, including the
producer organism.
4. Chemical nature and antigenicity
Most bacteriocins have been thermolabile (Tubylewicz and Uchiyama,
1966b; Mahony and Butler, 1971). Temperature sensitivity of the welchicins has been variable (Sasarman and Antohi, 1971). The bacteriocins
active only against C. perfringens and Streptococcus showed reduced activity
or complete inactivation above 50°C, while the activity of those inhibitory
only to C. perfringens or to Clostridium, Bacillus, and Streptococcus was not
reduced by temperatures up to and including 90°C for a period of 2 h.
Hirano and Imamura (1972~) reported two types of C. perfringens bacteriocin-one heat stable (type S) and the other thermolabile (type L). The
perfringocin described by Clarke et al. (1975) is heat stable (lOO°C, 10 min).
We currently have two bacteriocins which are similarly heat stable (Mahony,
unpublished data).
The sensitivity of bacteriocin to proteolytic enzymes was tested by
Tubylewicz (1966b). Both trypsin and papain completely inactivated perfringocin. Sasarman and Antohi (1971), Mahony and Butler (1971) and
Clarke (1975) reported similar results. The L type of Hirano and Imamura
(1972a, b, c) was trypsin sensitive, but the S type was not affected by
trypsin. Recently, we have observed two trypsin-resistant bacteriocins
of C. perfringens (Mahony, unpublished data).
Tubylewicz (1966b) studied the influence of UV rays on bacteriocins.
He found that, within a range of 537-12,888 erg/mm2, UV light did not
bring about any detectable change in the activity of bacteriocins a and b.
Similar findings were reported by Hirano and Imamura (1972) for both
their types of bacteriocins.
The influence of p H on bacteriocin activity was studied by Tubylewicz
(1966b) who noted stability over a pH range of 4-10. Uchiyama (1966b)
reported that their bacteriocins were inactivated below pH 3 and over
pH 9. The S type bacteriocin of Hirano and Imamura (1972a, b, c) was
D. E. MAHONY
existence of a new third class of welchicin which was active on C. perfringens
and Streptococcus, but not on many strains of the other genera listed
above.
A perfringocin active on C . pasteurianum has been described by Clarke
et al. (1975).
Resistance of the producing strain to its own bacteriocin is a usual
characteristic of bacteriocinogenic organisms, although one of the five
bacteriocins studied by Tubylewicz (1966a), bacteriocin d, was found to be
weakly active against the strain 496 from which it was derived, and one of the
strains reported by Sasarman and Antohi (1968), strain 1241, type E, produced a welchicin A active against all the strains tested, including the
producer organism.
4. Chemical nature and antigenicity
Most bacteriocins have been thermolabile (Tubylewicz and Uchiyama,
1966b; Mahony and Butler, 1971). Temperature sensitivity of the welchicins has been variable (Sasarman and Antohi, 1971). The bacteriocins
active only against C. perfringens and Streptococcus showed reduced activity
or complete inactivation above 50°C, while the activity of those inhibitory
only to C. perfringens or to Clostridium, Bacillus, and Streptococcus was not
reduced by temperatures up to and including 90°C for a period of 2 h.
Hirano and Imamura (1972~) reported two types of C. perfringens bacteriocin-one heat stable (type S) and the other thermolabile (type L). The
perfringocin described by Clarke et al. (1975) is heat stable (lOO°C, 10 min).
We currently have two bacteriocins which are similarly heat stable (Mahony,
unpublished data).
The sensitivity of bacteriocin to proteolytic enzymes was tested by
Tubylewicz (1966b). Both trypsin and papain completely inactivated perfringocin. Sasarman and Antohi (1971), Mahony and Butler (1971) and
Clarke (1975) reported similar results. The L type of Hirano and Imamura
(1972a, b, c) was trypsin sensitive, but the S type was not affected by
trypsin. Recently, we have observed two trypsin-resistant bacteriocins
of C. perfringens (Mahony, unpublished data).
Tubylewicz (1966b) studied the influence of UV rays on bacteriocins.
He found that, within a range of 537-12,888 erg/mm2, UV light did not
bring about any detectable change in the activity of bacteriocins a and b.
Similar findings were reported by Hirano and Imamura (1972) for both
their types of bacteriocins.
The influence of p H on bacteriocin activity was studied by Tubylewicz
(1966b) who noted stability over a pH range of 4-10. Uchiyama (1966b)
reported that their bacteriocins were inactivated below pH 3 and over
pH 9. The S type bacteriocin of Hirano and Imamura (1972a, b, c) was