Spore Germination in the Genus Bacillus: the Modification of Germination Requirements as a Result of Preheating

Abstract

SUMMARY : Spore suspensions of Bacillus megaterium germinated spontaneously after heat treatment. The extent of germination depended on the degree of close packing of the suspension, the temperature and duration of heating, and on the presence of water. Spontaneous germination was not inhibited by heating with cyanide, azide, 2 : 4-dinitrophenol or sodium iodoacetate, but was significantly inhibited by sodium fluoride.Freshly harvested spores of a laboratory strain of Bacillus cereus required either inosine or a mixture of alanine + tyrosine + adenosine for optimal germination.After prolonged storage or a short heat treatment, adenosine alone stimulated rapid and complete germination. Heat activation did not occur in the absence of water. It was inhibited to some extent by sodium fluoride. Similar results were obtained with B. cereus, NCTC 8035. After preheating, spores of a virulent and an avirulent strain of Bacitlus anthracis germinated more rapidly and completely in a mixture of adenosine + tyrosine + alanine, but not in adenosine alone. Inoaine stimulated rapid and complete germination of heated suspensions, and was consistently more effective than adenosine. Adenosine deaminase activity has been found in extracts from resting spores of the laboratory B. cereus and the avirulent strain of B. anthracis but not in B. rnegaterium.As in previous studies, the criterion of germination was loss of heat resistance accompanied by a change in staining properties, decrease of refractive index and decrease in dry weight (Powell & Strange, 1953). A laboratory strain of Bacillus megaterium which required glucose specifically for spore germination was described by Powell (1951). Some freshly harvested spore suspensions of this organism germinated very poorly in glucose solution but were activated by heating at 60" for 30 min. Other suspensions, grown on the same medium germinated completely in glucose solution without heat activation. It was later accidentally discovered that when thick spore suspensions (2 x 1010 spores/ml.) were heated at 60" for 1 to 2 hr., then centrifuged and resuspended in water, spontaneous and complete germination occurred without loss of viability. This behaviour provided a means of obtaining concentrated germination exudate (Powell & Strange, 1953). In suspensions thicker than 1 x 1O1O spores/ml. the amount of calcium dipicolinate excreted (Powell, 1953) was actually greater than the saturation concentration, and the substance appeared as a heavy white granular deposit. We have now studied this heat-activated germination in some detail. The modification of germination requirements as a result of preheating has also been studied in two strains of B. cereus and in a virulent and an avirulent strain of B. anthracis. Freshly harvested, unheated spore suspensions of these organisms germinated in a mixture of L-alanine+ tyrosine + adenosine (Hills, 1949).

Use of a lacZ Gene Fusion to Determine the Dependence Pattern and the Spore Compartment Expression of Sporulation Operon spoVA in spo Mutants of Bacillus subtilis

“…The frequency of germination was much lower in the t z z spores than in the 16 spores. This was understandable because cold-shocked spores at 16 respond well to germinants (Dion & Mandelstam, 1980), whereas more mature spores germinate efficiently only after heat shock (Powell & Hunter, 1955). Heat-shock treatment was avoided since this might have caused inactivation of P-galactosidase.…”

Bacteria and Actinomycetes Antogonistic to Fungal Root Pathogens in Australian Soils

“…For this reason, a simplified soil flora still exhibiting antagonistic qualities may be obtained by treatment of the soil at 60°C for 30 min. In addition, treatments at 60°C for 30 min also cause the spores of Bacillus to break dormancy (Powell and Hunter 1955).…”

Structural and stereospecific requirements for the nucleoside-triggered germination of Bacillus cereus spores

“…Purine nucleosides induce germination of spores of several bacterial species (Hills, 1949a;Lawrence, 19556;Powell & Hunter, 1955, 1956), but the mechanism of t Permanent address: Department of Food Microbiology, School of Medicine, University of Tokushima, Tokushima 770, Japan.…”