Biomedical Engineering Reference
In-Depth Information
contaminating bacteria, and (6) development of wort bioacidifi ying-LAB and/or
yeast starter cultures genetically modifi ed to produce bacteriocins. Although nisin
activity is limited to Gram-positive bacteria, the sensitivity of the Gram-negative
bacterium
Pectinatus frisingensis
to low nisin concentrations was reported in one
study (Chihib et al.
1999a
). However, selection of a strain resistant to high nisin
concentration was also described (Chihib et al.
1999b
). Nisin was reported to act
synergistically in combination with potassium metabisulphite against wine LAB,
and it was proposed that the addition of nisin could be applied in order to reduce the
concentrations of sulphur dioxide currently used in the wine industry (Bartowsky
2009
; Rojo-Bezares et al.
2007
).
Bacteriocins from strains of
Lactobacillus sakei
and
Ln. mesenteroides
isolated
from malted barley have been proposed as biological control agents in the brewing
industry (Vaughan et al.
2001
). Bacteriocins produced by bacterial strains from
other sources could also be useful, provided they inhibit target spoilage bacteria in
the brewing process. For example, application of thermophilin 110 from
Streptococcus thermophilus
in the brewing industry has been suggested based on its
high antimicrobial activity on pediococci (Gilbreth and Somkuti
2005
). Enterocins
have also been tested for biopreservation of beers. Enterocins L50A and L50B pro-
duced by strain
E. faecium
L50 were bactericidal against the most relevant beers
spoilage LAB (i.e.,
Lactobacillus brevis
and
Pediococcus damnosus
) in a dose- and
substrate-dependent manner when challenged in wort, alcoholic and non-alcoholic
lager beers at 32 °C. Enterocin addition achieved log reductions of ca 5 log cycles,
and no bacterial resistances were detected even after incubation for 6-15 days
(Basanta et al.
2008
).
Nisin addition is permitted in beer in certain countries, but not in wine. However,
nisin has been reported to act synergistically with sulphites against wine LAB
(Rojo-Bezares et al.
2007
). Nisin addition could aid to reduce the sulphite content
in musts before fermentation. One limitation of nisin addition in certain wines
would be inhibition of bacteria responsible for the malolactic fermentation. To solve
this shortcoming, nisin-resistant strains of
Oenococcus oeni
have been developed
that can grow and maintain malolactic wine fermentation in the presence of nisin.
Pediocins may also fi nd applications in wine. Pediocin N5p from
Pediococcus
pentosaceus
is resistant to the physico-chemical factors involved in vinifi cation i.e.
pH, temperature, ethanol and SO (Strasser de Saad et al.
1995
). Application of
pediocin PD-1 produced by
P. pentosaceus
isolated from beer, has been proposed in
removal of
O. oeni
biofi lms from stainless steel surfaces and also to control growth
of
O. oeni
in wine (Bauer et al.
2003
). PD-1 was the most effective bacteriocin in
removal of an established biofi lm from stainless steel surfaces in Chardonnay must
when compared with nisin and plantaricin 423 (Nel et al.
2002
).
Pediococcus acidi-
lactici
J347-29 produced pediocin PA-1 in presence of ethanol and grape must, sug-
gesting its potential biopreservative in winemaking (Díez et al.
2012
). The authors
tested the effect of pediocin PA-1 alone and in combination with sulphur dioxide
and ethanol on the growth of a collection of 53 oenological LAB, 18 acetic acid
bacteria and 16 yeast strains. Acetic acid bacteria and yeasts were not inhibited by
pediocin PA-1.
O. oeni
was the most sensitive bacterium compared with other wine
