Sunday 18 July 2010

Aspergillus nidulans (Emericella nidulans)

Aspergillus nidulans
Filamentous Fungus

Ecology - Widespread, ubiquitous soil organism found most frequently in tropical and sub-tropical climates.

- Colonies rapidly growing, green to cream-buff.
- Dark green to orange and yellow in areas with Cleistiothecal production.

- Brown to purplish exudates. Purplish reverse.
- Moderate to rapidly growing.
- Colonies dense, velutinous with floccose surface.

- Conidial heads radiate to loosely columnar.
- Conidiphore stipes 60-130 X 2.5 -3.0 μm.
- Phialides biseriate, limited to upper surface of the vesicle.
- conidia round, smooth to rugulose, (3-4 μm dia.) in short chains
- Cleistothecia often numerous, reddish-brown in colour.
- Hülle cells (10 - 25 μm dia.) typically present. Thick walled, smooth, often surrounding Cleistothecia.
- lenticular ascospores (within Clesitothecium), typically reddish-purple with two equatorial crests. Ascospores (4-6 X 3-4 μm) mature within 2 weeks.

-Teleiomorph = Emericella nidulans (Cleistiothecium = sexual state)
- Mycotoxin produced = Sterigmatocystin

Conidiphores Bearing Conidiospore chains, Also Hülle Cells
(Tape Preparation, LPCB X250)

Smooth Round Hülle Cells (10 - 25 μm dia.)
(X400, LPCB)

Emericella nidulans - Split Cleistothecium Releasing Ascospores
(Tape preparation in KOH - natural purple colour due to reaction of Cleistothecium contents with KOH -X400)*

Ascospore Contents of Cleistothecium With Hülle cells Present
(natural brownish colour of Ascospores and purple colour of those reacting with KOH)

(Intended as 1024 X 768 Wallpaper - May be re-sized by Blogger)
Aspergillus nidulans/Emericella nidulans
(Cleistothecium surrounded by Hülle cells, expelling ascospores)

*Make an adhesive tape preparation of Emericella nidulans (Cleistothecia) substituting KOH for LPCB. Once clestothecia located under the microscope, swing objective out of the way and use the eraser end of a pencil to press down on the tape thereby breaking cleistothecia open. Purple colour develops immediately when contents (ascospores) come in contact with the KOH base. May take several attempts to 'squash' , locate and refocus.