334 A MANUAL OF THE PENICILLIA 



bers of the Divaricata leads us to believe that the true relationship of the 

 species is with the latter. The species can best be assigned to the P. 

 nigricans series, although it differs from the more representative members 

 of this series by its more rapid growth and by producing conidia with walls 

 smooth or nearly so. 



In many species and strains, the character of conidiophore walls has 

 been observed to vary upon different substrata. In no species have such 

 differences surpassed those seen in Penicillium racihorskii, strain NRRL 

 2150. Upon Czapek's solution agar conidiophores are smooth or nearly so 

 as reported by both Zaleski (1927) and Thom (1930). Upon malt agar, 

 however, conidiophores, branches, and metulae are all conspicuously 

 roughened. The importance of recording the substratum upon which 

 observations are made is thus re-emphasized. 



Occurrence and Significance 



Members of the Penicillium nigricans series typically represent soil 

 molds which are widely distributed in nature, but which seem to occur less 

 frequently than other divaricate forms such as P. janthinellum and P. 

 lilacinum. Comparatively little attention has been given to their possible 

 role in decomposition processes. Oilman and Werkman (193G) reported 

 P. echinulatum (= P. nigricans) to reduce the organic matter in steamed 

 ground corn stalks by 16.9 percent within 21 days, as compared to 17.7 

 percent for Trichoderma lignorum and 30.0 percent for Chaetomium funi- 

 colum. Semeniuk and Ball (1937) found P. meUnii to be one of several 

 Penicillia commonly isolated from meat in cold storage lockers, but no 

 special significance was attached to its presence. 



Acid production by Penicillum kapuscinskii, P. swiecickii (see p. 329), 

 and P. janczewskii was investigated by Chrzaszcz and Tiukow (1929). 

 In a subsequent study the nitrogen metabolism of P. janczewskii in rela- 

 tion to citric acid formation was investigated Using cane sugar (8%) 

 as a carbon source, acid production tended to increase when certain amino 

 acids were added to the medium. Penicillium jenseni was reported to 

 produce both citric and oxalic acids. 



Brian, Curtis, and Hemming (194G) reported the production by Peni- 

 cillium janczewskii of an antibiotic substance possessing fungistatic proper- 

 ties. The substance, termed "curling factor", was observed to cause 

 unusual stunting and distortion of the germ tubes and hyphae of Botrytis 

 aim and other fungi. The factor was produced in maximum amount in 

 media containing 75 percent glucose, and could be removed by extraction 

 with chloroform, ether, n-butyl alcohol, or adsorption on activated char- 

 coal. Upon further purification, colorless crystals were obtained. Yields 

 up to 150 mg./liter were reported. More detailed information regarding 



