Abstract
Thirty two isolates of Aspergillus fumigatus were obtained from a total of 44 samples of sputum, nose swab and tracheal aspirate from suspected patient with aspergillosis were also collected from February 2014 to June 2014. A morphological examination of A. fumigatus was first made with naked eye and at low magnification power of microscope after that detailed examination was done by measuring the dimensions of the microscopic structures, photographing the microscopic structures and using relevant literature. Results appeared conical-shaped terminal vesicles, uniseriate row of phialides on the upper two thirds of the vesicle, conidiophore stipes were short, phialides arrange uniseriate upper vesicle conidia and parallel to axis of conidiophore, produced in chains of spore basipetally from phialides, the chains of spore were borne directly in the absence of metulae and represented by septet and branching hyphae. The ability of A. fumigatus for GT production was investigated using thin layer Chromatography (TLC) and High Performance Liquid Chromatography (HPLC) techniques and results showed that GT was produced by 81.25% of A. fumigatus isolates. Optimum conditions for GT production by A. fumigatus 16 (AF-16) isolate were determined by submerged fermentation using Yeast extract sucrose medium. Results indicated that AF-16 isolate was the highest GT producer on Yeast Exract Sucrose medium with inoculum size 2×107 conidium and incubation at 32ºC for 15 days and the concentration of gliotoxin was (4511µg mL-1).
Highlights
Gliotoxin is produced by number of fungi including: Aspergillus, Penicillium spp. by some species of Gliocladium, Thermoascus and Candida [1]
Screening of A .fumigatus isolates for gliotoxin production Inoculum Preparation Gliotoxin production on Yeast Extract Sucrose (YES) medium was achieved according to Kosalec [12] with some modifications, Each of 32 A. fumigatus isolates were grown on Sabouraud Dextrose Agar (SDA) plates for 2 days at 37°C and the conidia were harvested with sterile saline with 0.1% polysorbate 80
Upon culturing on Sabouraud dextrose agar SDA, colonies of A. fumigatus appear fast grower; the colony size reach 7cm within a week when grown on SDA at 37°C, the colony seems powdery, the color at the first seems to be white turning to dark greenish and changed to gray, reversed side of the colonies appeared pale yellow to tan Figure (1) which were in agreement with [14,15,16]
Summary
Gliotoxin is produced by number of fungi including: Aspergillus, Penicillium spp. by some species of Gliocladium, Thermoascus and Candida [1]. Gliotoxin (GT) primarily has immunosuppressive activity [2], and is considered as a virulence factor in human and animal aspergillosis and has immunosuppressive properties and inhibits mammalian cell proliferation [3]. It is capable of inhibiting function and inducing apoptotic cell death in macrophages and may alter the immune response [4], GT has been detected in lung tissue samples of poultry [5], and from aspergillosis human sputum [6] where it may facilitate fungal persistence and colonization of tissue. Separation and partial purification of GT produced in optimal conditions and detection it by TLC and HPLC techniques
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