204 A MANUAL OF THE ASPERGILLI 



ing groups. One basic character separating the two is the production of 

 sclerotia. Characteristic reddish-purple to black sclerotia are commonly 

 found in white-spored strains producing wholly or in part large globose 

 heads (A . candidus) ; they have never been seen in white-spored strains pro- 

 ducing only loose columnar heads (A . niveus). Until additional intermediate 

 forms are isolated and studied, the relationship between these white-spored 

 forms must remain a matter of conjecture, although in this manual they 

 are placed adjacent in what we believe to represent a natural placement of 

 the different groups. 



Pathogenesis 



Strains of A. terreus grow under a wide range of temperature, including 

 37° C. It is not surprising, therefore, that an occasional member of the 

 series is reported as a human parasite. One of these was re-described as 

 Stcrigmatocystis hortai by Langeron (1922). This culture, NRRL No. 274 

 (Thorn No. 5071.1), received from France, was originally isolated from a 

 human ear in Brazil. It is believed to be type and represents a characteris- 

 tic strain of A. terreus. Another was found in metastatic lesions on a corn- 

 husker's hand and forearm in Nebraska. Recently a strain was isolated 

 from an aborted fetus from a cow in Maryland; the culture was entirely 

 typical of A. terreus. 



Occurrence and Economic Importance 



Members of the Aspergillus terreus group are typically soil organisms, 

 hence are most abundant in soil and upon decaying vegetation. They 

 frequently occur, however, upon a great variety of materials useful to man, 

 including grains in storage, straw and forage products, cotton and other 

 fibrous materials not adequately protected from excessive moisture, etc. 

 Aspergillus terreus and Aspergillus carneus are especially widespread in warm 

 arable soils, and have been isolated in great abundance from soils collected 

 in southern and southwestern United States. They are generally less com- 

 mon in forest than in cultivated soils, and are rarely found in acid forest 

 soils from the colder temperate zone. There is little evidence that these 

 forms are especially active agents of decay, but their great abundance in 

 nature indicates that they undoubtedly play a significant role in the slow 

 decomposition of organic materials. Aspergillus terreus and A. carneus 

 grow well at temperatures of 35 to 37° C, a character which possibly 

 accounts for their great abundance in southern soils and their relative scar- 

 city in soils from northern areas. 



Aspergillus terreus has become of special biochemical interest since the 

 discovery in 1939 by Calam, Oxford, and Raistrick that certain strains of 

 this species are capable of producing itaconic acid from sugars. Extensive 



