302 A MANUAL OF THE PENICILLIA 



ber4789 as listed in his IMonograph (1930, p. 341), NRRL 904 isolated from 

 Virginia soil in 1928, NRRL 2016 isolated from Nicaragua soil in 1945, 

 and numerous other strains now in our possession or examined in previous 

 years. 



This species is probably the most abundant Penicillium found in soils, 

 having been isolated from samples world-wide in origin. It is also 

 commonly isolated from decaying vegetation undergoing final stages of 

 decomposition. While not so frequently isolated from fabrics or other 

 military equipment as members of the Penicillium citrinum series or the 

 P. luteum series, these forms are commonly obtained from these and re- 

 lated sources. 



In soil dilution plates, Penicillium. janthinellum characteristically appears 

 as a rapidly spreading, medium to light sporulating form with colony 

 surface often orange to vinaceous in color and with reverse typically in 

 bright orange-red to purple-red shades. When first isolated and grown 

 in laboratory culture, individual strains usually produce this characteristic 

 picture but, upon continued cultivation, tend to become less highly colored 

 and to produce fewer conidial structures. After 10 or more years of con- 

 tinuous laboratory cultivation many strains become essentially sterile 

 and fail to produce characteristic colors either in their vegetative mycelium 

 or the colony reverse. NRRL 904 represents such a strain. When 

 isolated in 1928 this strain was highly colored and was considered repre- 

 sentative of the species; today it is almost sterile, produces colonies with 

 vegetative hyphae cream to flesh-colored and with colony reverse ranging 

 from peach to pale orange. However, the penicilli produced, and par- 

 ticularly the sterigmata, remain wholly characteristic of the species. A 

 culture received from the Centraalbureau under this name is comparatively 

 heavy sporing, develops a minimum of colored vegetative hyphae, and 

 produces colonies with reverse in peach shades. The penicilli produced by 

 it are likewise characteristic of the species. Strain NRRL 2016, noted 

 above, is regarded as entirely typical of the species as it is understood by 

 us. It sporulates fairly abundantly and produces colonies on Czapek and 

 steep agars in which both the vegetative mycelium and the colony reverse 

 are highly colored. By relying upon the lyophil technique for culture 

 preservation (see p. 79) it is hoped that this culture may be kept in an 

 unaltered form for many years. 



Penicillium guttulosum Gilman and Abbott (Iowa State College, Jour. Sci. 1: 298, 

 fig. 33. 1927) was described to cover some member of the P. janthinellum series char- 

 acterized by the production of an excessive amount of exudate. The original descrip- 

 tion was written in terms which clearly ally it with P. janthinellum. Since exudate 

 production is an extremely variable character in the latter species, we regard P. guttu- 

 losum as representing merely an extreme variant in this abundant and diverse series. 



