Phosphoroclastic Reactions of Clostridium Nigrificans.

Emmons (B2318), C. W. Hesseltine (Emmons A1238), and A. M. M. Wilson (B37). Replicate Sabouraud's dextrose agar plates were inoculated at five evenly dispersed sites with growth from 7-day-old Sabouraud's agar slants grown at 22 to 25 C. Each site was approximately 1 mm2. Duplicate plates of each strain were incubated at 15, 25, and 37 C. Through 48 hr, colonies were discrete and circular, and growth could easily be measured by diameter; but by 72 hr the colonies often were contiguous, and growth was recorded as maximal width. Table 1 shows the difference in the ability of B. ranarum, isolated from various sources, to grow at the temperature of the human body. Those isolated from subcutaneous phycomycosis grew well at 37 C, whereas those cultured from nature grew either poorly or not at all. Other species of Basidiobolus (B. meristosporus and B. microsporus), however, possessed the ability to grow at 37 C, although clearly not so well as the strains pathogenic for man (Table 2). These observations suggest that species of Basidiobolus isolated from natural habitats may not be pathogenic for man, inasmuch as they are unable to grow at temperatures of the human body. The possibility that the pathogenic phycomycete may represent a new species of Basidiobolus is under investigation by others (Emmons, personal communication).