Biomedical Engineering Reference
In-Depth Information
2.2
Antimicrobials from Animal Sources
Antimicrobial proteins and peptides
are naturally found as part of the defense sys-
tem of living organisms (including humans, animals, plants, insects…). Lysozyme,
lactoferrin and ovotransferrin are illustrative examples. Lysozyme from different
sources is commercialized as a natural preservative for food applications, either
singly or in combination with other antimicrobials. Lysozyme is generally recog-
nized as safe (GRAS) for direct addition to foods (FDA
1998
). Lactoferrin (and its
partial hydrolysis derivative lactoferricin) is another natural protein (which is found
in milk and other secretions) with antimicrobial activity due to its iron-binding
capacity and polycationic nature (Ellison
1994
). Lactoferrin shows antimicrobial
activity against a wide range of bacteria (including foodbone pathogens like
Carnobacterium, L. monocytogenes, E. coli
, and
Klebsiella
) and viruses (Lönnerdal
2011
; Gyawali and Ibrahim
2014
), and has been approved for application on beef in
the United States and has been applied as an antimicrobial in a variety of meat prod-
ucts (Juneja et al.
2012
; USDA-FSIS
2010
).
Lactoperoxidase is another antimicrobial system that originated from milk and is
reported to be effective against gram-negative bacteria (de Wir and van Hooydonk
1996
). Ovotransferrin has a high affi nity for iron, and inhibits bacterial growth due
to iron deprivation (Valenti et al.
1987
). Interestingly, hydrolysis of natural proteins
may yield peptide fragments with diverse biological activities, including antimicro-
bial activity (Möller et al.
2008
). Following a strategy of “tailoring and modelling,”
a number of short peptides with high bactericidal activity have been developed from
the bactericidal domain of lysozyme. Ovotransferrin, alpha-lactalbumin and beta-
lactoglobulin have also been investigated as sources of antimicrobial peptides
(Pellegrini
2003
).
Protamine
is composed of cationic antimicrobial peptides naturally present in
spermatic cells of fi sh, birds and mammals (Rodman et al.
1984
) and is commer-
cially recovered from herring (clupeine) and salmon (salmine) milt. With a MW of
4,112 Da and a pI of 11-13, protamine is the most cationic naturally occurring cat-
ionic antimicrobial peptide described to date (Potter et al.
2005
). It shows broad
antimicrobial activity against gram-positive bacteria, gram-negative bacteria, and
fungi (Uyttendaele and Debevere
1994
). Protamine has been used to preserve a
wide variety of foods ranging from confection items to fruits and rice.
Pleurocidin
is present in myeloid cells and mucosal tissues of many vertebrates
and Invertebrates (Jia et al.
2000
). It shows antimicrobial activity against several
foodborne bacteria, such as
L. monocytogenes
and
E. coli
O157:H7, and pathogenic
fungi (Burrowes et al.
2004
; Jung et al.
2007
).
Chitosan
is a polycationic biopolymer naturally present in the exoskeletons of
crustaceans and arthropods (Tikhonov et al.
2006
). Partially and fully deacetylated
chitosan derivatives of low molecular weight are available, with broad antibacte-
rial and antifungal activity (Franklin and Snow
1981
; Kong et al.
2010
). Chitosan
is considered a safe food additive. Reported antibacterial activity for chitosan
