الفهرس 
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Abstract
The area of fungal biosynthesis of AgNPs is a relatively new area being reported in the literature; however it has great advantages over bacterial synthesis. The mechanism of fungal biosynthesis has not been fully elucidated in the literature. The main purpose of this thesis was to the following:
1. Evaluate the potential of Fusarium isolates from a different
location of field soil samples to tolerate different concentrations of
silver metal ion.
2. Isolates of Fusarium spp. were resistances to silver nitrate were
screening for their ability to synthesize silver nanoparticles from
silver nitrate (AgNO3).
3. The biomedical applications of silver nanoparticles in respect to
their antimicrobial activity.
Evaluate the potential of Fusarium isolates to tolerate different
concentrations of silver ion
1. A number of 22 Fusarium isolates were obtained from the soil
samples on plating the sample on Potato Dextrose Agar medium.
2. Twenty two isolates tested for their growth in Czapek-Dox Agar
medium supplemented with 1mM silver nitrate in order to further
determine the most efficient tolerate strains to silver nitrate. Based
on it’s tolerate to silver nitrate, fifteen fungal isolates collection
from different field soil samples were selected for further study.
3. After tolerance test the results showed that out of the fifteen
isolates from 4 different sites namely T18, T22, TA, MB, KHG and
KhD were tolerant when grown on Czapek-Dox Agar media supplemented with 2.5 mM of silver nitrate. These isolates were selected for further study.
4. Optimization of cultural parameters of six Fusarium isolates was
investigated. In physiological studies, the Fusarium isolates grew
best on Czapex Dox Agar medium, glucose was found to be the
best carbon source, sodium nitrate (NaNO3) was the best nitrogen
source, best pH was at 7 and 0.2 % NaCl was the best salinity level.
Screening Fusarium resistances to silver nitrate for their ability to synthesize silver nanoparticles
1. Six isolates of Fusarium. (T18, T22, TA, MB, KHG and KHD)
were resistant to silver nitrate (up to 2 mM). These isolates were
screening for their ability to synthesize silver nanoparticles from
silver nitrate (AgNO3). from the results of colour change and UVVisible, only three isolates T18, TA, and KHG showed brown
colour and strong surface plasmon resonance centered at around ca.
420 nm, is characteristic of colloidal silver.
2. Based on the morphological characteristics and sequence analysis
of 18S rRNA, Fusarium strains capable of synthesize silver
nanoparticles were belonged to the general F. oxysporum,
F.graminearum and F. solani.
3. Parametric optimization studies revealed that temperature of 25oC,
pH 6, substrate concentration of 1.5 mM, salinity concentration of 0.1 % NaCl and incubation time 72 hrs were favorable for the production of silver nanoparticles by three Fusarium isolates.
Characterization of silver nanoparticles
1. Fungal cell filtrate treated with silver nitrate (1.5 mM) showed the
sharp peak at around ca. 420 nm with high absorbance (F. oxysporum at 4.43 nm, F. graminearum at 3.67 nm and F. Solani
nm at 3.38) which is very specific for silver nanoparticles which increased in absorbance with increasing time of incubation.
2. from the TEM microscopy, the particles obtained exhibited a
regular spherical shape with smooth surfaces and the size was
distributed in a range of about 5-80 nm.
3. The XRD pattern of the as-prepared Ag nanoparticles shows that
they held a cubic crystal structure. The major strong characteristic
peaks of silver nanoparticles are at 2θ =38.5°, 40.185°, 77.74°
which were corresponding to crystal faces of (111), (111) and (311)
of silver nanoparticles.
4. The protein fraction clearly showed absence of bands in the cell
filtrate treated with silver nitrate (1.5 mM) compared to untreated
filtrate.
5. The FTIR showed the presence of two bands at 1636, 1542 and
1514 cm-1 are identified as the amide I and amide II arises due to
carbonyl stretch and -N-H stretch vibrations in the amide linkages
of the proteins, respectively.
6. The antibacterial activity for the silver nanoparticles was carried
out using five different human pathogenic bacteria strains. All the
five microbes that were tested were inhibited at low concentrations
of nanoparticles. In addition, inhibition zone caused by silver
nanoparticles gradually increased with S. aureus and MRSA (Gram
positive), compared with E. coli, K. pneumonia and A. hydrophi
(Gram negative). However, no inhibition zones were visible in the
cell-free water extract alone.