Science into Practice
Jackie Linden
Limited control
of salmonella by
bacteriophages
Researchers at the University
of Arkansas have concluded that
bacteriophages vary in their
efficacy in reducing colonisation
by Salmonella enteritidis (SE) in
poultry, and that the effect was only
short-term.
Bacteriophages are viruses that
have the ability to kill specific
types of bacteria. Salmonella
enterica serovar Enteritidis-lysing
bacteriophages were isolated from
poultry or human sewage sources,
and tested in their ability to reduce
SE in vitro (crop assay) and in
experimentally infected chickens.
All of the treatments significantly
reduced SE recovered from the
caecal tonsils of the infected chicks
at 24 hours but no differences were
observed after 48 hours.
Andreatti Filho R.L. et al.,
2007. Ability of bacteriophages
isolated from different sources to
reduce Salmonella enterica serovar
enteritidis in vitro and in vivo.
Poultry Science, 86:1904-1909
Irradiation of
poultrymeat
A group of Korean researchers
has compared irradition and
organic acid treatment of raw
chicken meat to control pathogenic
organisms. They found that
irradiation was an excellent
method for controlling inoculated
micro-organisms but that the
content of biogenic amines was
similar to that found with the
organic acid treatment.
Bacillus cereus, Enterobacter
cloacae and Alcaligenes faecalis were
inoculated into raw chicken breast
and thigh meat. The samples were
irradiated at 0, 0.5, 1.0 and 2.0kGy
or mixed with a 0.2 molar solution
of acetic, citric or lactic acid for
24 hours at 4°C. Irradiation was
effective in reducing the inoculated
bacterial count: 0.5kGy achieved
a 2-log reduction and no viable
cells were detected following 2kGy.
Generally, organic acid treatment
produced a 1-log reduction in
bacterial cell count. The reduction
in biogenic amine level caused by
the treatments was inconsistent.
Min J.S. et al., 2007. Control of
microorganisms and reduction of
biogenic amines in chicken breast
and thigh by irradiation and organic
acids. Poultry Science, 86: 2034-2041
Dioxin levels in
free-range eggs
Dioxins have adverse effects on
human health, resulting in limits
being set for foods in the European
Union (EU). Eggs from free-range
hens have been found to contain
higher levels of dioxins than from
birds that are confined, and a group
from Wageningen University in the
Netherlands has looked into this
difference further with a study of 34
organic egg farms. Eggs from 10 of these
farms exceeded the limits for dioxins
or toxic equivalents (TEQ; includes
polychlorinated biphenyls.) set by the
EU (3pg TEQ per gramme of egg fat).
There was an interesting
relationship between flock size
and egg dioxin levels. Previous
research indicates that the larger
the flock, the greater the proportion
of hens that choose to remain
inside. The Wageningen researchers
hypothesised that the dioxin level in
eggs could be reduced to acceptable
levels by restricting the time that
the birds are allowed access to the
