الفهرس 
Literature reviewOnly 14 pages are availabe for public view
 |  | from | 234 |  |  |
| | | from | 234 | | |
Abstract
I- Abstract
Chitin is one of the most widely distributed biopolymers on Earth, however its low solubility restricts its use and applications. Chitosan which is produced by deacetylation of chitin exhibits a wide range of applications due to its bioactivity, and biodegradability. Fungal chitosan has better physico-chemical properties than the chitosan extracted from crustaceans, and so it is in high demand. In the current study, marine derived fungal isolates have been subjected to chitosan extraction (crude chitosan and total chitosan). The fungus giving the maximum chitosan yield was identified according to morphological and molecular characteristics. Statistical optimization of fungal growth conditions for maximum chitosan yield was done using Plackett Burman design (PBD) and central composite design (CCD). The produced chitosan was afterwards characterized by Fourier transform infrared spectroscopy (FTIR), deacetylation degree (DD%), X-ray diffraction (XRD), and solubility. Ultrasonication method was applied to produce nanosized chitosan nanoparticles. Chitosan nanoparticles (CSNPs) were characterized by different methods as FTIR, XRD, transmission electron microscope (TEM), and zeta potential by dynamic light scattering (DLS). CSNPs were applied as an antimicrobial agent and in water treatment for removal of dyes. Results have shown that maximum crude and total chitosan
was produced from Penicillium sp. which was later identified molecularly as Penicillium chrysogenum and was deposited in GenBank with accession number MZ723110. The statistical optimization revealed that fungal culture method, peptone concentration, and incubation period were the most significant factors. The chitosan yield after optimization reached 7.5% with DD% equal to 94% and 70% solubility. FTIR analysis and XRD pattern confirmed the formation of chitosan nanoparticles using ultrasonication method. The resulting TEM pictures showed that the produced nanoparticles size ranged from 6 to 24 nm. Zeta potential value of chitosan nanoparticles obtained from P. chrysogenum MZ723110 was +25.6 mV at pH 4 with low polydispersity index (PDI) values of 0.553. Chitosan nanoparticles had antimicrobial activity against gram positive bacteria Staphylococcus aureus ATCC 29213 with MIC equal to 78 μg/ml and an antifungal activity against yeast fungi (Candida albicans) at a dosage of only 20 mg/mL. Also, the mycelial growth of Alternaria solani EMCC-756 after 7 days was inhibited by 30% using CSNPs. For the treatment of water from dyes, CSNPs were not active in the removal of rhodamine B and fluorescein dye by adsorption method but were active in the removal of methylene blue dye at concentration equal to 0.75, 1×10-5 mole/L where the removal efficiency reached 77%. The results of this study confirmed the importance of optimizing fungal growth conditions
for the maximum yield of chitosan and the efficiency of using ultrasonication method in the production of CSNPs with applications in the medical field as an antimicrobial agent and in the environmental field for the treatment of water in the removal of dyes.