A technique for the rapid selection of drug-sensitive and auxotrophic mutants of Phycomyces blakesleeanus.

An auxotroph enrichment procedure has been developed for Phycomyces blakesleeanus which has proven useful in obtaining both auxotrophs and drug-sensitive mutants. The technique is based on the differential heat sensitivity between ungerminated auxotrophic spores and germinated prototrophic spores. Germinated spores and mycelia die when left at temperatures higher than about 35 degrees C for 16 to 24 h but ungerminated spores survive this treatment and subsequently germinate if transferred to complete medium. With the dwarf colonial strain, replica plating permits the rapid characterization of these newly selected auxotrophs.