404 A MANUAL OF THE PENICILLTA 



cillium roqueforti upon moist bran, -vyhich was then dried after the enzyme 

 content reached a maximum. 



Irvine and Sproule (1940) and Willingham (1941) reported propionic 

 acid to be an effective inhibitor of molds in dairy products, including cheese. 

 Salts of this acid were less effective. 



Penicillium brevi-compactum Series 

 Outstanding Characters 



Colonies usually restricted, typically consisting of a close-textured felt, 

 with surface growth velvety to almost lanose, often conspicuously fur- 

 rowed, heavy sporing, in dull yellow-green to gray-green shades, reverse 

 usually in dull yellow, greenish gray, or brownish shades. 



Conidiophores variable in length, with longer individuals borne from the 

 substratum and shorter stalks borne as branches from aerial hyphae, 

 smooth or somewhat roughened. 



Marginal stolons typically produced in all members of the series, especially 

 when cultivated upon moist substrata or under very humid conditions. 



Penicilli asymmetric, typically branched, short and compact with branches 

 appressed, metulae and sterigmata numerous and closely crowded; in 

 some strains unbranched, consisting of a compact terminal cluster of 

 metulae bearing crowded sterigmata. 



Conidia subglobose to more or less pyriform or elliptical, smooth or deli- 

 cately roughened, borne in fairly long tangled chains. 



Series Key 



B. Penicilli comparatively short, compact, with all elements closely appressed. 



P. hrevi-com/pactuyn series 



1. Penicillus typically showing one or more side branches below the level of 



metulae. 



a. Conidiophores coarse, with branches and metulae commonly inflated. 



P. hrevi -com pactum Dierckx 



b. Conidiophores thinner, flexuous, with branches and metulae not inflated. 



P. stoloniferum Thorn 



2. Penicillus typically consisting of a single, crowded terminal verticil of 5 to 8 



metulae P- paxilli Bainier 



Members of this series are encountered among isolates from all soils 

 examined. While comparatively abundant, they do not, because of their 

 slow and limited growth, attract the immediate attention commanded by 

 more rapidly growing and more highly colored members of other series. 

 They commonly occur upon decaying vegetation, nuts, fruit, paper stocks, 

 etc. , and seem to be somewhat selective of fleshy fungi as habitats. Thom's 

 type of Penicillium stoloniferum was isolated from such a source; Bainier's 

 P. paxilli was based upon an isolate from a moldy Paxillus, hence the name; 



