Loss of Aerial Mycelium and other Changes in Streptomycete Development due to Physical Variations of Cultural Conditions

Abstract

SUMMARY : Several isolates of monosporous lines of Streptomyces coelicolor, both normally pigmented and colourless variants, were obtained by microdissection of young vegetative mycelia. In each case their properties largely resembled those of the parents. This material was studied together with three strains of Streptomyces scabies of varying degrees of virulence, which had been isolated from potato scab lesions. Modifications of growth were noted with respect to gross colonial morphology on agars containing detergents, structure of aerial mycelium arising from various types of surfaces, and development of germinating spores in liquids and in contact with non-nutritive plane surfaces. In both species-groups those organisms which produced least aerial mycelium on stock nutrient agar were most susceptible to the inhibitory influence of 0-01 yo Gemex 29 on the development of aerial mycelium in simpler media. Distorted aerial growths on detergent agar resembled irregular swollen sporogenous filaments produced in pectin + ammonium salt liquid media.These were also reminiscent of cases of sporogenesis in submerged cultures described by other workers. Apart from surface tensions operating at the air/medium interface, the relative degree of humidity in the culture vessel was found to have some effect upon variation of spore size. Germinating spores and young filaments growing in contact with plane surfaces were more prone to elongation than those growing in liquids. Branching was also influenced to a considerable extent by the nature of the physical environment.In a recent review Hendlin (1954) pointed out that inadequate attention has in the past been paid to the profound effect which the physical environment must have upon the nutrition of micro-organisms. Such a viewpoint, which was restricted by Hendlin mainly to a consideration of such physical factors as temperature, pH values, oxidation-reduction potential, and CO, tensions in so far as they cause perceptible nutritional differences, can almost certainly be extended to other aspects of microbiology. Thus the alteration of the energy relationships at interfaces which is brought about by the addition of surfaceactive agents to the media in which various acid-fast bacteria are grown is a recognized method of altering the character of the growth of the organisms (Alexander & Soltys, 1946). Increased cell division and smaller cells result from the incorporation of Tween 80 in the media in which the non-acid-fast Nocardia turbata (Erikson, 1954) is cultivated. A certain degree of correlation has been noted between decreased humidity on the one hand, and increased production of sporogenous aerial mycelium by streptomycetes on the other (von Plotho, 1940;Erikson, 1947), suggesting that important phases in the development of a complex organism may be favoured or completely suppressed by fluctuations in the physical environment.

The Life-cycle of <i>Streptomyces griseoflavus</i>

“…According to these authors, there are three types of organs which initiate new mycelial growth: 1) "segmentation spores" formed in a vegetative phase of mycelial growth; 2) long cylindrical structures termed "birches" which appear to be occasionally formed during a sporulation phase; and, 3) "conidia" arising from "elements speciforme" or "massues" which develop in the same sporulation phase. Erikson (1955) studied Streptomyces coelicolor and Streptomyces scabies and observed a variety of different cell types. She interpreted some to be the result of cultural conditions and some the artefacts of staining.…”

Forty years of genetics with Streptomyces: from in vivo through in vitro to in silico

“…However, it could not be substantiated. Erikson (1955) had found that aerial hyphae of the A3(2) strain arose as simple side-branches of vegetative hyphae anywhere over the colonies. I confirmed this (Fig.…”

Production of actinorhodin-related "blue pigments" by Streptomyces coelicolor A3(2)

“…1). S. coelicolor A3(2), a strain isolated independently (14) and the subject of most genetic work, was also found to produce actinorhodin (18,40), but related pigments were not sought. The pH-dependent color transition of actinorhodin, exploited to isolate mutants of S. coelicolor A3(2) impaired in actinorhodin biosynthesis (35), has been used extensively for cloning and mapping of the act gene cluster (16,29,30).…”