Explain some Features of Aspergillus?
The identifying features include:
1. Macroscopically Aspergillus colonies are powdery and are of different colours like green, blue, black, yellow, brown etc.
2. Microscopically mycelium consists of branched, bright or pale coloured hyphae some of which grow within the substrate while others grow on the substrate.
3. From these vegetative hyphae, long, unbranched, nonseptate erect hyphae arise called conidiophores. The cell from which conidiophore arise is called foot cell. It is thick walled and T-shaped and one conidiophore arises from each foot cell.
4. Conidiophores terminate into a globular structure called vesicle
5. Around the vesicle, there are 1-2 layers of flask shaped structures called phialides or sterigmata.
6. At the tip of the sterigmata, a chain of small unicellular spores called conidia arises. These conidia are formed in basipetal manner (oldest is at the top). These are arranged compactly side by side. The whole structure consisting of the foot cell, the upright hypha, the vesicle, the metullae and the phialides constitutes the conidiophore.
7. Sexual Reproduction occurs by formation of ascus and ascospores.