Chapter XX 

 THE ASPERGILLUS FLAVUS-ORYZAE GROUP 



Outstanding Characters 



Colonies varying from very light greenish-yellow to deep yellow-green 



(Ivy Green). 

 Conidiophores rough or pitted, colorless. 

 Heads hemispherical to columnar to subglobosc. 

 Sterigmata in one or two series, often varying in the same head. 

 Vesicles variable in form, from hemispherical to dome-shaped in small 



heads to globose in large heads. 

 Conidia more or less roughened, varying in color as the colony. 

 Sclerotia characteristic of many strains, generally grayish-brown to 



black, entirely lacking in others. 



Two species names are widely used for members of this cosmopolitan 

 group. Aspergillus oryzae is applied quite generally, without regard to 

 morphology, to the strains used by the Japanese and Chinese in the fermen- 

 tation of rice and soy products. Although purified cultures are used in 

 many places, the nomenclature is based more upon utilization than upon 

 morphology. There appears, however, in these industries, a series of strains 

 with long conidiophores, radiate heads, mostly greenish-yellow, with the 

 green often fading completely in old cultures. These strains appear to be 

 most commonly used in the production of the diastatic type of ferments and 

 to be distributed in the great culture collections as Aspergillus oryzae 

 (Ahlb.) Cohn. Such strains seem to be mostly oriental or tropical in origin. 

 Strains with shorter conidiophores and yellowish-green heads, on the other 

 hand, appear wherever fermenting or decaying materials are examined 

 microscopically, or by culture. Aspergillus flavus Link has been accepted 

 as a species aggregate for this second array of forms from which the segrega- 

 tion of sections for description as separate species has been found difficult, 

 if not almost impossible. If one wishes to perpetuate species names as 

 roughly covering aggregates of closely related but varying strains, bearing 

 always in mind that no sharp lines of differentiation exist, certain applica- 

 tions of names may be made arbitrarily about as follows: 



Group Key 



I. Sterigmata mostly in one series, double sterigmata also present. 



A. Conidiophores long, 1-several mm., heads radiate, greenish-yellow; conidia 

 pyriform, more or less roughened, variable in size up to 6, 8, or even 10ju 

 in long axis A . oryzae ( Ahlburg) Cohn 



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