186 A MANUAL OF THE PENICILLIA 



Occurrence and Significance 



Pennicillum frequentans Westling and P. spinulosum Thorn are two of 

 the most abvmdant and widely distributed members of the monoverti- 

 cillate PenicilHa. Penicillium purpurrescens (Sopp) n. comb, is somewhat 

 less common. Members of this series typically represent soil fungi and in 

 our experience constitute a normal component of the mycoflora of all 

 soils examined. Like many other soil fungi, and in greater abundance 

 than most, they occur in nature under a wide range of conditions and upon 

 a great diversity of substrata. They may be found upon almost any 

 type of organic material which is undergoing slow aerobic decomposition. 

 A few references will serve to illustrate this range. Penicilliurn spinulo- 

 sum was one of the species most commonly isolated by Snow (1945) from 

 oats, linseed cake, and palm kernel cake stored at 75 percent to 100 per- 

 cent R.H. Gopp, Christ, and Reich (1937) reported Citromyces pfefferi- 

 anus Wehmer (= P. spinulosum Thom of this Manual) as one of a group 

 of fungi causing extensive mold growth and impairment of aroma in stored 

 hops. Ullscheck (1928) reported P. spinulosum to represent one of nine 

 types of Penicillium commonly encountered in the cheese cellar. Grimes, 

 et al. (1930) found P. spinulosum to be generally present in butter although 

 no special significance was attributed to it. In testing various fungicides 

 for their efficacy in "tropic-proofing" optical instruments. Turner, et al. 

 (1946) cited P. spinulosum as one of the molds commonly isolated from 

 such instruments in New Guinea, and in our experience it was commonly 

 encountered among cultures isolated from materiel and submitted to us 

 for identification. Richter (1931) reported species of Citromyces without 

 further identification, but probably belonging to this series, to be re- 

 sponsible for mustiness in seed grain. James, Wilson, and Stark (1946) 

 reported P. spinulosum as one of the molds commonly identified in the 

 flora of stored wheat. Passmore (1931) identified P. candido-fulvum 

 Dierckx (= P. frequentans Westling of this Manual) among the molds 

 isolated from, and responsible for, the spoilage of prepared copra. Peni- 

 cillium frequentans was used by Hoffman, et al. (1940) to assay the fungi- 

 static properties of acetic and proprionic acids in which chlorine substitu- 

 tions had been made. 



A possible role of the above forms in decay processes in nature is indi- 

 cated by their ability to decompose tannin. Rippel and Keseling (1941) 

 reported species of Penicillium, Citromyces, and Aspergillus to be able to 

 utilize tannin as a source of carbon. Tannase was produced only in the 

 presence of tannin but was not associated with the ability of the mold to 

 utilize this substance. Stapp and Bortels (1935) found a number of molds 

 belonging to the present series to be capable of growing in concentrated 

 tannin hquors. Two new species, Penicillium tannophagum and P. 



