DORMANCY OF BACTERIAL ENDOSPORES: REGULATION OF ELECTRON TRANSPORT BY DIPICOLINIC ACID

Calcium dipicolinic acid-induced germination of Bacillus cereus spores

Keynan, A. (University of Wisconsin, Madison) and H. O. Halvorson. Calcium dipicolinic acid-induced germination of Bacillus cereus spores. J. Bacteriol. 83:100-105. 1962.-The germination of spores of Bacillus cereus strain T can be initiated by calcium dipicolinic acid. The kinetics of germination are characterized by a long lag period followed by a rapid loss of refractility. The lag period displays the temperature dependence of a metabolic reaction, whereas the rate of germination is relatively independent of temperature. Germination induced by calcium dipicolinic acid is insensitive to l-alanine analogues, is sensitive to metabolic poisons, and proceeds without a detectable activation stage. It was concluded that calcium dipicolinic acid-induced germination has a metabolic basis and differs, at least in its initial phases, from l-alanine-induced germination.

Morphogenesis of the membrane-bound electron-transport system in sporulating Bacillus megaterium KM

The properties of electron transport systems present in soluble and particulate fractions of spores of Bacillus megaterium KM?HAVE BEEN COMPARED WIth those of similar fractions prepared from exponential-phase vegetative cells of this organism. The timing and localization of modifications of the electron transport system occurring during sporulation have been investigated by using a system for separating forespores from mother cells at all stages during development [8]. Spore membranes contained cytochromes a + a3, and o at lower concentrations than in vegetative membranes, and in addition cytochrome c, which was not found in exponential-phase vegetative membranes. An NADH oxidase activity of similar specific activity was found in both spore and vegetative membranes but DL-glycerol 3-phosphate and L-malate oxidase activities were found only in vegetative membranes. A soluble NADH oxidase of low specific activity was found in spores and vegetative cells which probably involves a flavoprotein reaction with oxygen because the activity was stimulated by FAD or FMN and difference spectra of concentrated soluble fractions showed spectra typical of a flavoprotein. Particulate NADH oxidase was sensitive to all classical inhibitors of electron transport tested whereas soluble NADH oxidase was insensitive to many of these inhibitors. Cytochrome c was formed between stage I and II of sporulation and this coincided with a five-fold increase in NADH-cytochrome c reductase activity. Forespore membranes had lower contents of cytochromes than sporangial cell membranes but similar levels of NADH and L-malate oxidases; DL-glycerol 3-phosphate oxidase activity could not be detected in either membranes by stage III of sporulation. This characterization of spore electron transport systems provides a basis for suggestions concerning initial metabolic events during spore germination and the effect of a number of germination inhibitors.

Alpha-alpha'-dipyridyl or ortho-phenanthroline stimulation of the soluble reduced nicotinamide adenine dinucleotide oxidase from Bacillus subtilis spores and dipicolinic acid inhibition of the stimulated enzymes

Soluble reduced nicotinamide adenine dinucleotide oxidase activity in extracts of Bacillus subtilis spores was stimulated by the addition of not only flavine mononucleotide (FMN) or flavine adenine dinucleotide (FAD) but also alpha-alpha'-dipyridyl or o-phenanthroline. These chelating agents showed stronger effect on the enzyme from spores than on that from vegetative cells. Activity stimulated by alpha-alpha'-dipyridyl or o-phenanthroline was inhibited by atabrine or dipicolinic acid, whereas FMN or FAD stimulation was inhibited only by atabrine.