Abstract
Reproducible colony counts of spore suspensions of Rhizopus nigricans and Penicillium digitatum have been obtained on a malt medium containing 0.02 per cent rose bengal. Spores of these organisms suspended in different strengths of Ringer's solution and stored at 1.4° lost viability after a lag of up to 2 days. A spray-dried peptone powder containing evenly distributed R. nigricans spores has been prepared without loss of viability of the spores.