Method for inducing sporulation of pure cultures of the myxomycete Physarum polycephalum.

Daniel, John W. (University of Wisconsin, Madison) and Harold P. Rusch. Method for inducing sporulation of pure cultures of the myxomycete Physarum polycephalum. J. Bacteriol. 83:234-240. 1962.-Techniques for inducing sporulation of pure cultures of Physarum polycephalum are described. Small plasmodia grown in agitated culture were harvested, allowed to fuse into large plasmodia (1.3 g wet weight each), and, after incubation in the dark on a salts medium, exposed to light for 2 hr. The ensuing formation of sporangia containing spores was complete after 12 to 16 hr. The obligatory conditions for sporulation are: (i) an optimal growth age occurring just prior to the maximal growth of the organism and at a time when nutrients in the medium are exhausted; (ii) 4 days of incubation on a medium containing only inorganic salts and niacin or tryptophan; and (iii) subsequent illumination with light of wavelengths between 350 and 500 mmu.