Function and location of a "germination enzyme" in spores of Bacillus cereus.

An enzyme extracted from Bacillus cereus spores caused to germinate spores of this organism which had been sensitized by reagents which rupture disulphide bonds. Inactivation of the enzyme by thiol-blocking agents and by oxidation, and reactivation by reduction suggested that the enzyme’s ability to germinate spores depended on thiol groups. No evidence was obtained to support the hypothesis that the enzyme was present in dormant spores in the oxidized inactive form and became reduced and active during germination. When spores were disrupted at pH 3 the enzyme was found to be bound to debris; probably on or within the central core of the spore. At pH 5.8 or below the enzyme remained bound to the debris, but a t pH 7.0 the enzyme was irreversibly released when the ionic strength of the medium was high. In solutions of sodium phosphate less than 0.05 M, the enzyme remained mostly bound even at pH 7-0. It was largely released when the concentration of sodium phosphate was increased to 0.2 M. Extracts of germinated spores contained more unbound and less bound enzyme than extracts of ungerminated spores, suggesting that release of enzyme from a bound form occurred during germination of the spores.