Morphology of spore-bearing structures in Streptomyces ipomoea.

Sporulating colonies of Streptomyces ipomoea were observed using light and scanning electron microscopy. In addition to the open loops and spiral chains of spores characteristic of S. ipomoea, globose structures resembling sporangia of the genus Streptosporangium were found. The "sporangia" had a smooth surface, were 5-6 micrometers in diameter, and consisted of an unbranched coiled hypha within an enveloping sheath. As the sporangia matured, septa formed in the internal sporogenous hypha forming coiled chains of spores morphologically similar to those formed on the typical spore chains. The sporangia germinated on agar, without releasing the nonmotile spores, by formation of several germ tubes at several locations on the sporangia.