Daniel, John W. (University of Wisconsin, Madison), Karlee L. Babcock, Alice H. Sievert, and Harold P. Rusch. Organic requirements and synthetic media for growth of the myxomycete Physarum polycephalum. J. Bacteriol. 86:324-331. 1963.-An isolate of Physarum polycephalum was maintained in submersed pure culture in a completely defined medium, giving cell yields approximately 70% of those obtained in a partially defined medium. Optimal concentrations of the absolute organic requirements, identified as d- or l-methionine, biotin, thiamine, and hematin as previously reported, were established. Glycine was highly stimulatory. In a minimal medium, alanine or glutamine, not required in the complete medium, stimulated growth and appeared to function as sources for transamination. Arginine was also required in the minimal medium. The cell yield in a simplified medium containing the absolute requirements plus glycine, alanine, and arginine was approximately the same as that in the complete medium, but the growth rate was about 25% lower.