Preliminary Studies on a Hyphaforming Mutant of Cryptococcus Neoformans

SUMMARY

In the Coward strain of Cryptococcus neoformans, a stable mutant was found which repeatedly produced true hyphae and verticil-like groups of blastospores when inoculated into modified Sabouraud's agar by the cut-streak method or when cultured subsurface in pour plates. On the surface of agar this mutant produced yeast-like colonies and had biochemical and mouse pathogenicity characteristics typical of C. neoformans.

Preliminary studies of 34 other clinical isolates of C. neoformans indicated that at least two additional strains have the potential for hyphal production.

Therefore, we believe that mutation leading to hyphal formation does occur rarely in C. neoformans. However, because C. neoformans is rarely cultured under conditions ideal for its immergence in agar, this phenomenon is not often seen or correctly interpreted.