Mycelentwicklung und Sporenbildung von Streptomyces ramulosus Ettlinger et al.

Abstract

The type-strain of Streptomyces ramuloses Ettlinger et al. ETH 17653 (= ATCC 19802) was studied by phase contrast microscopy, scanning electron microscopy and transmission electron microscopy. During germination the spores may pass through three stages: darkening, swelling and emergence of the germ tube. In poor media swelling is not always essential for the development of germ tubes. The hyphae of primary mycelium are phase dark. Sporulating hyphae of aerial mycelium are phase bright, relatively thick and show in scanning electron microscopy a slightly roughened surface due to the surrounding sheath.

The spores develop in short, straight or slightly curved chains forming a monopodially branched system. Sporulation starts with the formation of simple, solid septa dividing the sporogenous hyphae into compartments of spore size. The spore wall is formed de novo. At first a thin but electron-dense layer is deposited to which a more electron-transparent layer is added. During spore wall formation the material of the septa and the parent hyphal wall begins to autolyze. Mature spores evidence only slight remnants of septa forming connections from spore to spore.

The morphology of the spore chains and the fine structure of the sporulation process confirms the exceptional position of Streptomyces ramulosus.