曲霉属黄绿组的一个产毒新种

本文报道曲霉属黄绿组(通常称黄曲霉群)的一个产毒新种肇庆曲霉(Aspergillus zhaoqingensis sp.nov.)。该菌分离广东肇庆土壤,在形态上近于米曲霉(A.oryzae),但作为该组的关键分类特征分生孢子纹饰很不相同:本种的分生孢子明显的粗疏粗糙至具不规则的脊状突起而米曲霉则为光滑或稍粗糙。本种能产生黄曲霉毒素B_1而米曲霉则不产生。本菌亦不同于组内其它菌种。文中对与黄曲霉密切相关诸种也作了简短的讨论。

A NEW AFLATOXIN PRODUCING SPECIES OF SECT. FLAVI OF ASPERGILLUS

A new aflatoxin producing species, Aspergillus zhaoqingensis, is described. Colonies on Czapeks solution agar growing rapidly at 25℃, attaining a diam. of 65 mm in 12—14 days; deeply velvety to floccose, white; conidial structures developing later, sparse or unevenly distributed, at first Light Cress Green to Cress Green (R. xxx), shifting with age to Olive Ochre or Light Brownish Olive (R. xxx); occasionally developing white mycelial masses, becoming sclerotia in age, brownish black; exudate lacking or accompanied by sclerotia, uncoloured; reverse pale brown. Conidial heads globose to radiate, 300—600(—1000)μm, sometimes spliting into loose columns; conidiophores arising from substrate or aerial hyphae, variable in length, commonly 1000—3000(—5000)×10—22μm, much shorter when borne from aerial hyphae, smooth or slightly ronghened; vesicles thick walled, fertile over three fourth of the surface, subglobose or flask shaped, (16—)30—60(—80)μm, predominatly biseriate; metulae (8—)16—24×(3—)4.8—9.6μm; phialides (5—)8—14.4×3—4μm, rarely uniseriate on small vesicles; conidia globose to subglobose, (3—)4—5.6μin, or ovate to pyriform (6—)6.4—7.2(—9)×4—5.6μm, coarsely roughened or irregularly ridged; occasional production of sclerotia, globose 500—750(—1000)μm or vertically elongate, 750—1300×500—1000μm, blackish brown. This species, accarding to all its features, belongs to Sect. Flavi (=Aspergillus flavus group Raper & Fennell, 1965). It is closely related to Aspergillus oryzae (Ahlb.) Cohn, but differs markedly from the latter in conidial ornamentation, a key character used for separating related species. Moreover, it possesses strong aflatoxin producing ability on GAN (Glucose Ammonium Nitrate) and rice media (26,666.7 and 120,000 ppb respectively). This species is also different from other species of Sect. Flavi described so far, hence the establishment of a separate species. This fungus was isolated from soil collecteed in Zhaoqing, Guangdong Province, China. The type specimen HMAS 58980 and living culture AS 3.4626 have been deposited in the Institute of Microbiology, Academia Sinica, Beijing.