Ultrastructural studies of sporulation in Streptomyces

Abstract

This is the first study of sporogenesis in Streptomyces carried out on a relatively high number of species (seven) which allows us, using also previously published results, to establish a general picture of this process. In the sporogenesis of Streptomyces two basic stages can be considered: the sporulation septum synthesis and the arthrospore maturation. Our ultrastructural study of the sporulation septum formation suggests the existence within this genus of three basic types. Type I is distinguished because the septum is formed from the beginning by two separate cross walls. Within this type we include Streptomyces erythraeus, Streptomyces albus, and Streptomyces aureofaciens and also include Streptomyces venezuelae, Streptomyces griseus, and Streptomyces osteogriseus. Type II is distinguished because there is a deposit of material previous to the synthesis of the double annulus which completes the septum. This type can be divided into two subtypes. In the first the deposits are wedge-shaped and the double annulus is clearly visible, and to this group belong Streptomyces flaveolus, Streptomyces ambofaciens, and Streptomyces coelicolor. In the second the deposits, which have a different shape and are very well developed, constitute almost entirely the sporulation septum in which the double annulus is barely visible; Streptomyces antibioticus and also Streptomyces viridochromogenes belong to this group. Type III, represented by Streptomyces cinnamonensis, is distinguished because the septum is formed by a single cross wall.The genus Streptomyces belonging to the order Actinomycetales shows a comparatively complex development cycle in which from a branched vegetative mycelium submerged in the substrate is formed an aerial mycelium with hyphae of greater diameter. Through the sporulation process these aerial hyphae give rise to chains of arthrospores, which placed under favorable conditions germinate and repeat the cycle.The term arthrospores has been proposed by Cross (5) to refer to the asexual spores produced by Streptomyces that are formed by the annular ingrowth of specialized, regularly spaced cross walls in existing hyphae enclosed in a fibrQus sheath. The arthrospores are differentiated from bacterial endospores both by the sporogenesis process and by their properties.In recent years great interest has been shown in the study of sporulation processes in bacteria, because they constitute a simple, and therefore an attractive, model for the study of a process of cellular differentiation. Although most of these studies are performed on species of two genera Bacillus and Clostridium, several works have been published on the different processes of sporulation within the Actinomycetes, particularly in the genera Streptomyces and Thermoactinomyces (6).In this paper we present the results of the ultrastructural study of the sporulation in seven species of Streptomyces. We compare these results with those obtained previously by other authors and make a tentative classification of the genus Streptomyces according to ...

Bacterial pro‐transglutaminase from Streptoverticillium mobaraense

“…Streptomyces species possess multicellular differentiation mechanisms unusual among procaryotes [30]. Cell development, especially metamorphosis of aerial hyphae to chains of spores, is accompanied with changes in shape and thickness to their walls [31,32]. Further, sporulation is associated with the expression of extracellular proteins for example sapA and sapB [33].…”

A note on the determination of the sporulation septum type in Streptomyces

“…With respect to the variation in width found within Type I1 it is important to underline the fact that we have previously reported the existence of two subgroups (Hardisson & Manzanal 1976). In some instances the deposits have the form of a wedge and the two annuli which complete the septum are clearly visible [ S .…”

“…In previous studies (Hardisson & Manzanal 1976;Manzanal & Hardisson 1978) the existence of three morphological types of sporulation septum within the genus Streptomyces has been described. These three types were characterized on the basis of the formation of the sporulation septum and its modification during spore maturation.…”

Structural changes induced by glycine on Streptomyces antibioticus

“…In this work we studied the effect of glycine on the filamentous bacterium Streptomyces antibioticus ATCC 11891. This strain, which produces the macrolide antibiotic oleandomycin, has been the subject of many physiological and morphological studies [4][5][6][7][8]. The pathway of biosynthesis of oleandomycin and the mechanism of resistance of the strain to the antibiotic it produces are also under investigation [9][10][11].…”