Search on : Taxa descriptions


Page number:347 
Remarks (internal):Of many strains examined, the following cultures are considered as representative of the species in its different aspects : WB 303, from Professor Westerdijk in 1909 as A. candidus Link; WB 312, from Dr. Reis in 1939, Instituto Biologico, Brazil; WB 313, from Teizo Takahashi in 1919 as A. okazakii Okazaki; WB 4646, local isolate from barn litter; and WB 4809, from the Institute for Fermentation, Osaka, Japan, as No. 4319, A. albus var. 1 Yamazaki. 
Description type:Non-original description 
Description:Aspergillus candidus Link, in Observationes, p. 16, (1809). Thom and Church, The Aspergilli, p. 157, (1926); see also Thom and Raper, A Manual of the Aspergilli, pp. 207-210, Plate 6A, Figs. 59, 60 (1945).
Colonies on Czapek's solution agar usually slow growing reaching diameters of from 1.5 to 3.0 cm. in 2 weeks at room temperature (24-26°C), usually thin, with vegetative mycelium largely submerged and surface growth consisting only of fruiting structures borne directly from the substrate (Fig. 73A) or from a scanty aerial mycelium, but with occasional strains developing a dense basal felt (Fig. 73B) and a surface growth which may attain a depth of 2 mm., persistently white, or becoming cream to yellowish cream; purple to black sclerotia produced in occasional strains; reverse of thin colonies uncolored, in strains with more compact basal mycelium very pale yellow to faintly pink, in occasional strains producing a blackish purple halo in age; exudate lacking; odor not distinctive. Conidial heads white to cream, at first globose, with spore chains later adherent in loose divergent columns and reaching diameters of 600 to 800 µm (Figs. 72 and 73D) occasionally appearing loosely columnar in heads with incomplete development of sterigmatic surface, young heads varying in the same culture from globose masses 200 to 300 µm in diameter to small heads less than 100 µm in diameter; conidiophores varying with the strain from less than 500 µm long up to 1000 µm or longer, and from 5 µm to 10 or 20 µm in diameter, thick walled, smooth, occasionally septate, colorless or slightly yellowed in age in some strains; vesicles globose to subglobose, ranging from 40 µm or more in diameter in very large heads (Fig. 74A) to less than 10 µm in small heads (Fig. 74B), typically fertile over the whole surface, but small vesicles often bearing only a limited number of primary sterigmata and appearing almost penicillate (Fig. 74D); sterigmata occasionally uniseriate in young or small heads but typically in two series, colorless, primaries varying greatly in different strains, in different heads of the same strain, and occasionally in the same head (Fig. 74C), characteristically wedge shaped but with dimensions ranging from 5.0 to 8.0 µm by 2.5 to 3.5 µm to 25 to 30 µm by 10 to 12 µm, occasionally septate; secondaries usually more uniform in dimensions from 5.0 to 8.0 µm by 2.0 to 2.5 or 3.0 µm; conidia globose or subglobose in most strains to elliptical in others, thin walled, 2.5 to 3.5 µm or occasionally 4 µm smooth, colorless; sclerotia (Fig. 73C), when produced, at first white, quickly becoming reddish purple to black, consisting of thick-walled parenchyma-like cells.
Colonies on malt extract agar growing somewhat more rapidly, in some strains reaching a diameter of 5 cm. in 2 weeks at room temperature, usually plane, about 1 mm. deep and heavily sporulating, with conidal heads white to ivory; less frequently floccose, up to 5 mm. deep and almost nonsporulating; reverse uncolored to yellowish; exudate lacking; odor not distinctive. Conidial heads less variable in form than on. Czapek's agar, less frequently penicillate and with primary sterigmata showing fewer aberrancies, but with the range of dimensions of conidiophores, vesicles, and primary sterigmata unchanged.
Colonies on MY20 agar growing well, attaining diameters of from 4 to 7 cm. in 2 weeks at room temperature, occasionally floccose and up to 4 to 5 mm. deep but usually plane, velvety, heavily sporing throughout, white to cream or even pale pinkish cinnamon (R., Plate XXIX) at colony centers, where conidial heads absorb pigment from the reddish purple sclerotia, in some strains conspicuously zonate; reverse uncolored to slightly yellow in strains lacking sclerotia, dull red-brown to gray-drab shades under areas of heavy sclerotium development. Conidial heads show maximum development and least variability on this medium.
Taxon name: