الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
 |  | from | 174 |  |  |
| | | from | 174 | | |
Abstract
NPs having a size of 1-100 nm in one dimension could be used in many fields, such as medicine, chemistry, atomic physics, and all other known fields, which can be used immensely due to their small size, as they showed new or improved properties, in the distribution, size, and morphology of the particles. One type of those NPs is AgNPs could be synthesized using various approaches including physical, chemical, and biological methods. Among all of the NPs synthesis methods, biosynthesis method is the safest, cheapest, and produces large quantities. Those NPs could be used as antimicrobial agents as they could strongly interact with thiol groups of vital enzymes and inactivates them. In addition, DNA loses its replication ability once the bacteria have been treated with silver ions, and other studies have shown evidence of changes in the structure of cell membrane, so these NPs could be used as a treatment for infection of dermatophyte fungi and MDRB that are a big problem that people faces.
For that, this study aimed to biosynthesizing the AgNPs and using them as antimicrobial agents against dermatophyte
fungi and MDRB. The results can be summarized in the following paragraphs.
Microbial load of samples were 24 isolate. Fourteen bacterial isolates, three fungal isolates and seven actinobacterial isolates.
Screening of microorganisms that were isolated from the manure of poultry was done to test their ability to biosynthesis NPs, then AgNPs biosynthesis was detected by visual observation of turning of the solution color from yellow to brown color. Uv-Visible spectrophotometer, which showed spectra between 400-420 nm, was used to confirm the presence of AgNPs. Then, particle size of biosynthesized AgNPs was measured by DLS.
After that, the microbial isolates that synthesized the smallest NPs (36.78 nm), was identified using biochemical tests, and 16S rRNA, then was identified as Bacillus mansourensis sp., and has the accession number of KT982274.
The parameters of biosynthesis of the smallest size of AgNPs by using cell free filtrate of Bacillus mansourensis sp. KT982274 were tested. These were: Culture age, which resulted in AgNPs biosynthesis at the smallest size 34.01nm after 96h. Then, AgNO3 to bacterial filtrate volume ratio 1:1
resulted in 31.03 nm AgNPs size. Then, reaction temperature at
40 C allowed biosynthesis of the smallest size 30.79 nm. After that, reaction incubation time at 18 h allowed biosynthesis of AgNPs 28.27 nm. Finally, pH of the reaction at
7, resulted in biosynthesis of the smallest AgNPs size (4.86
nm).
DLS, HR-TEM, EDAX, FT-IR, and atomic absorption spectrophotometer was used to characterize NPs.
The biosynthesized AgNPs was characterized by DLS as a spherical shape with ~ 4 nm. TEM examination of the solution containing AgNPs demonstrated spherical particles within nano range from 4 nm. EDX spectrum recorded showed sharp peak between 2.5 and 5 keV. XRD peaks were at 38.4°,
44.7°, 64.1° and 77.1°. Absorbance bands of FT-IR seen at
3458.6, 1631.2 and 1442.2 cm-1, which were assigned to the NH stretching vibrations of free NH group, C=C stretching vibrations of non-conjugated group and CH bending vibrations of CH3 group respectively. Then concentration of AgNPs was assessed by atomic absorption spectrophotometry, which found
530 ppm, to use this concentration to calculate the MIC of AgNPs on some dermatophyte fungal strains and MDRB strains.
At the final, antimicrobial effect of the final synthesized NPs showed that MIC of each pathogenic microorganism was detected as following: After 3 h, it was 2 μg/ml for Pseudomonas aeruginosae, 265 μg/ml for Klebsiella pneumoniae, and 8 μg/ml for Acinetobacter baumannii. While after 6 h, it was 1 μg/ml for Pseudomonas aeruginosae, 33 μg/ml for Klebsiella pneumoniae, and 2 μg/ml for Acinetobacter baumannii. With respect to deratophytes, after 3 h it was 132 μg/ml, and 265 μg/ml for Microsporum audouinii, and Tricoptyton violaceum, respectively. While after 6 h, it was 8 μg/ml, 66 μg/ml, and 33 μg/ml for Microsporum audouinii, Tricoptyton violaceum and Candida albicans, respectively.
TEM studies proved that sublethal dose of AgNPs affect viability of MDRB and dermatophytes. The effects were cell wall rupture, rupture of the organelles, and cytoplasm aggregation. After 6 h, it was more efficient than 3 h.
So the synthesized AgNPs were proved to have antimicrobial activity against all the tested microorganisms.