Biomedical Engineering Reference
In-Depth Information
activities of ampicillin, kanamycin, erythromycin, and chloramphenicol were
increased in the presence of AgNPs against test strains, ampicillin showed the highest
enhancing effect.
Also food-storage possibilities of biofabricated NPs were examined using the
same organism (Fayaz et al.
2009
). Antibacterial activities of AgNP-incorporated
sodium alginate films were tested against
E. coli
ATCC 8739 and
S. aureus
ATCC
6538 strains - disk method exhibited antibacterial activity against both G+ and G−
bacteria. Antimicrobial coating was applied to carrot and pear surface and conser-
vation impact was examined compare to untreated samples.
3.4.2
Antifungal and Combined Activity
Although there are reports of biosynthesized NPs with antifungal activity, they usually
exhibit it only in combination with antibacterial activity. It is in this context, then,
that they will be mentioned in the following text.
Mycelia-free water extracts from
Amylomyces rouxii
facilitated the production of
stable, monodispersed and spherical AgNPs (size range of 5-27 nm). Biosynthesized
AgNPs exhibited antimicrobial activity against bacterial (
Shigella dysenteriae type I,
Staphylococcus aureus, Citrobacter sp., E. coli, Pseudomonas aeruginosa, Bacillus
subtilis
) as well as fungal (
Candida albicans, Fusarium oxysporum
) species.
Biological reduction of aqueous silver ions by extracellular components of
Streptomyces hygroscopicus
(Sadhasivam et al.
2010
) resulted in AgNPs which sig-
nificantly inhibited the growth of medically important pathogenic gram-positive
bacteria (
Bacillus subtilis, Enterococcus faecalis
), gram-negative bacteria (
Escherichia
coli
and
Salmonella typhimurium
) and yeast (
Candida albicans
). The colloidal
AgNPs biosynthesized with filtrate from
Aspergillus niger
inhibited the growth of the
fungus itself (seeded in the nutrient agar plate). Potential antifungal activity was due
to inactivation of sulfhydryl groups in the fungal cell wall and disruption of mem-
brane bound enzymes and lipids which causes the cell lysis (Jaidev and Narasimha
2010
). Antibacterial activity against both G+ (
Staphylococcus sp., Bacillus sp.
) and
G− (
E. coli
) bacterial species was observed. Similar results were obtained employing
Aspergillus clavatus
(against
Candida albicans, Pseudomonas fluorescens
and
Escherichia coli
) by Verma et al. (
2010
). Also, Govindaraju et al. (
2010
) published
study utilizing
Solanum torvum
as mediator for biosynthesis of AgNPs eliciting anti-
bacterial activity against pathogenic bacteria
Pseudomonas aeruginosa
,
Staphylococcus
aureus
, pathogenic fungi
Aspergillus flavus
and
Aspergillus niger
.
Interestingly, extracts from tissue culture-derived callus and leaf of the saltmarsh
plant
Sesuvium portulacastrum
were used for AgNPs growth (Nabikhan et al.
2010
). The antibacterial activity (
Pseudomonas aeruginosa, Staphylococcus
aureus, Listeria monocytogenes, Micrococcus luteus, Klebsiella pneumoniae
) was
more distinct compared to antifungal (
Alternaria alternata, Penicillium italicum,
Fusarium equisetii
,
Candida albicans
) activity. Moreover, antimicrobial activity
was enhanced when polyvinyl alcohol was added as a stabilizing agent (in compari-
son with samples prepared with distilled water).
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