Aspergillus flavus Link

SRRC 1304

Macroscopic characters

Colony diameter after seven days on CYA at 25°C 50-70 mm; conidia olive green (1-3C-E4-7) to parrot green (3OE8); exudate absent; reverse uncolored to pale buff; soluble pigment absent. Colonies on MEA 50-70 mm in diameter; conidia olive; no exudate or soluble pigment; reverse uncolored to pale buff. Colonies on CY20S 50-70 mm in diameter; conidia olive to yellow-green; exudate and soluble pigment absent; reverse uncolored. Colonies on CZ 40-52 mm in diameter; conidia yellow green; exudate and soluble pigment absent; reverse uncolored. Colonies on CYA at 37°C 45-70 mm in diameter. Black sclerotia usually present on at least one medium.

Microscopic characters

Stipes 450-1000 um long, hyaline, walls finely rough to rough. Vesicles 30-35 um wide, hyaline, globose, subglobose to pyriform in shape. Aspergilli uniseriate or biseriate. Conidia 3.8-5 um in diameter, globose to subglobose, surface texture finely rough to rough at 1OOX.

Note

This common species is of great economic importance because many isolates produce the potent carcinogen aflatoxin in foods and feeds. Several detection media have been developed (see Samson 1992, 1994). There are several species that are morphologically very similar to A. flavus. Great care should be taken in separating them (see Klich and Pitt 1988b, Klich and Mullaney 1987, 1989).

Plate 3. Aspergillus flavus Link SRRC 1304

A. Colony on CYA, 7 days at 25°C.
B. Macrograph of the conidial heads showing radiate and columnar heads.
C-D. Conidiophores: C. 250x; D. 900x.
E. Conidia 1470x.

Aspergillus Reference Cultures