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length of the alkyl chain. Hence, the length
of the alkyl chain is associated with elicit-
ing activity to a large extent.
The knowledge obtained may provide a
new insight into the bactericidal action of
2
E
-alkenals on a molecular basis, and allow
a more rational and scientific approach to the
design of efficient and safe anti-
Salmonella
agents. For example, a minute amount of
the medium-chain 2
E
-alkenals, such as
2
E
-dodecenal and 2
E
-undecenal, can be
added to the artificial fodder to control
Salmonella
bacteria. Thus, 2
E
-alkenals have
potential as a crop preservative to inhibit or
prevent the growth of
Salmonella
bacteria.
It should be noted, however, that 2
E
-alkenals
are highly reactive chemicals, which may
limit their practical application.
Lastly, it may be worthwhile to consider
the anti-
Salmonella
activity of rather com-
mon phytochemicals from an ecological
point of view. For example, green leaves
containing a variety of antibacterial agents
against
Salmonella
bacteria, especially those
known as green leaf alcohols and aldehydes
(Hatanaka, 1993), very likely to have con-
trolled
Salmonella
in nature when chickens
were continuously fed green-leaf-based
foods. In the Amazon basin,
Salmonella
con-
tamination of pepper has been increasingly
noted with increasing large-scale poultry
farms. This may be caused by shifting their
foods from plant-based natural foods to arti-
ficial fodders. Although it is not possible to
affirm that membrane damage is the only
cause of the lethal effect, it can be concluded
that the medium-chain alkanols target the
extracytoplasmic region as surfactants. This
is highly desirable because they do not need
to enter the cell, thus avoiding most cellular
pump-based resistance mechanisms. In
addition, primary alcohols are considered to
be chemically stable, colourless, inexpen-
sive, biodegradable and essentially non-
toxic to humans. Therefore, a minute amount
of the medium-chain alcohols can be added
to the artificial fodders to control
Salmonella
bacteria. Thus, alcohols have potential as
crop preservatives to inhibit or prevent the
growth of
Salmonella
bacteria.
Acknowledgements
The authors are indebted to ABEP, Pará,
Brazil, for the opportunity to explore this
interesting science, and Dr S.H. Lee and Dr
A. Kubo for in part performing antimicro-
bial assays.
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