Agriculture Reference
In-Depth Information
nanofiber showed bacteriostatic effect after 10 cycles against
S. aureus
,
Bacillus
cereus
,
Shigella flexneri
, and
Pseudomonas aeruginosa
, demonstrating that it is a
promising material for antimicrobial delivery (Park et al.
2013
). Bacteriocins have
been also incorporated into electrospun nanofibers. The bacteriocin plantaricin
423 was in PEO nanofiber and maintained its antimicrobial activity after
electrospinning inhibiting the growth of
Enterococcus faecium
and
Lactobacillus
sakei
(Heunis et al.
2010
).
Spasova et al. (
2011
) prepared nanofibrous mats containing chitosan and
T. viride
spores by electrospinning. It was observed that
T. viride
placed at 28
C
grows much faster and competes for space and nutrients against
Fusarium
sp. and
Alternaria
sp. In addition,
T. viride
produces extracellular hydrolytic enzymes,
which directly attack the pathogens and destroy their cell walls. The spores incor-
porated into the nanofibrous mats are viable, and
T. viride
maintained its ability to
inhibit the growth of phytopathogens tested.
6.3.6 Carbon Nanotubes
CNTs are a structure having potential for diffusion of antimicrobials. Two classes
of CNTs are described, namely, single-walled nanotubes (SWCNTs), which consist
of a single graphite sheet impeccably wrapped into a cylindrical tube with a
diameter between 0.4 and 2.5 nm, and multiwalled carbon nanotubes (MWCNTs),
which comprise more layers of graphite sheet with different diameters of up to
100 nm. The length of the tubes ranges from a few nanometers to a few microme-
ters. The unique structure of CNTs offers excellent physical and chemical proper-
ties that allow a wide range of applications (Zhang et al.
2010b
). Their elevated
loading capacity and ability to readily penetrate membranes represent a potential
for antimicrobial delivery.
In a recent study, Chen et al. (
2013
) suggested that CNTs may selectively lyse
the walls and membranes of human gut bacteria, depending not only on the length
and surface functional groups of CNTs but also the shapes of the bacteria. The
mechanism of antibacterial activity was associated with their diameter-dependent
penetrating and length-dependent enfolding on the lysis of microbial walls and
membranes, inducing release of intracellular components and loss of bacterial
membrane potential, resulting in a complete destruction of bacteria. Thin and
rigid SWCNTs show more effective wall/membrane penetration on spherical bac-
teria than MWCNTs. Long MWCNT may be covering around gut bacteria, increas-
ing the area making contact with the bacterial wall. Thus, CNTs may be broad-
spectrum antibacterial agents in the gut, and selective application of CNTs could
reduce the potential hazard to probiotic bacteria.
SWCNTs dispersed with surfactants like sodium cholate displayed an extended
antimicrobial effect and low toxicity to human cells (Dong et al.
2012
).
Nanocomposite films with embedded antimicrobial lysostaphin-carbon nanotube
conjugates are effective to combat methicillin-resistant
S. aureus
, reducing viable
