Slide Culture Observations of Two Freshwater Actinomycetes

The complete life cycle of two odoriferous aquatic actinomycetes was observed in slide cultures. Branching of the vegetative mycelium yielded sporogenous hyphae. Frequent intimate contacts were observed between vegetative hyphae produced by the same or by different spores. No "initial cells" were detected. Contrary to previous reports, these aquatic actinomycetes appeared to be true streptomycetes and lacked an isogamous reproductive pattern. Vegetative mycelium developed pigments, sporogenous hyphae and odor under aerobic conditions, but not when grown under an atmosphere of inert gases or in the presence of 300 ppm malonate. Only small amounts of sporogenous hyphae could be produced by washed vegetative mycelium suspended in a balanced salt solution.