Improving Conditions for Gliotoxin Production by Local Isolates of Aspergillus fumigatus

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).