Biomedical Engineering Reference
In-Depth Information
below the detectable limit after 15 days of drying, but it had no effect on the viabil-
ity of the listeria during sausage fermentation. By comparison, the results obtained
with the Bac + strain
L. curvatus
LBPE were superior, with highly signifi cant reduc-
tions during fermentation and ripening (Benkerroum et al.
2005
).
Several LAB strains may antagonise growth o
E. coli
O157:H7 in fermented sau-
sages. This inhibitory effect has been attributed to the production of small antimicro-
bial compounds (such as reuterin, 3-hydroxy fatty acids, phenyllactic acid, and
4-hydroxyphenyllactic acid and novel bacteriocins; Leroy et al.
2006
). It was shown
that inoculation of salami with strains of
Lactobacillus
spp. as well as bifi dobacteria
reduced the levels of
L. monocytogenes
and
E. coli
O111 during fermentation of
sausage batter (Pidcock et al.
2002
). Similar results were reported for
Lactobacillus
reuteri
and
Bifi dobacterium longum
in dry fermented sausages. In the treatment con-
taining
L. reuteri
(producer of reuterin), a 3 log CFU/g reduction in
E. coli
O157:H7
numbers was found at the end of drying, while
B. longun
was reported to have lower
effects (1.9 log CFU/g reduction) (Muthukumarasamy and Holley
2007
).
Staphylococci and micrococci may also be exploited as sources for antibacterial
substances applicable in sausage fermentations. The introduction of the lysostaphin
gene (an endopeptidase that specifi cally cleaves the glycine-glycine bonds unique
to the interpeptide cross-bridge of the
S. aureus
cell wall) into meat starter lactoba-
cilli (Cavadini et al.
1998
) is an interesting approach to prevent the growth of
S.
aureus
. Furthermore, one
Staphylococcus xylosus
sausage isolate that produces an
antilisterial substance increased the microbial inactivation of
L. monocytogenes
in
Naples-type sausage (Villani et al.
1997
).
Kocuria varians
(formerly
Micrococcus
varians
) produces the lantibiotic variacin (Pridmore et al.
1996
). Strains producing
this lantibiotic were isolated form Italian-type raw salami fermentations.
Bacteriocinogenic
Kocuria
strains could be very interesting as adjunct protective
cultures in meat fermentations.
References
Amezquita A, Brashears MM (2002) Competitive inhibition of
Listeria monocytogenes
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Ananou S, Garriga M, Hugas M et al (2005a) Control of
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Ananou S, Maqueda M, MartÃnez-Bueno M et al (2005b) Control of
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in
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Antara NS, Sujaya IN, Yokota A et al (2004) Effects of indigenous starter cultures on the microbial
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