ACTIVATION OF BACTERIAL ENDOSPORES

Abstract

Heat activation of bacterial endospores was imitated by suspending spores in reducing agents (mercaptoethanol or thioglycolate) or in a pH less than 4.5. Urea (6 M) had no effect on spores. In addition to the well-known activation at 65 C for 45 min. spores were also activated by exposure to 34 C for 48 hr. The activation by heat and by reducing agents was reversible; the reverse reaction was temperature-dependent. No reversion occurred at -20 C, whereas at 28 C the spores reversed to their original dormant state within 72 hr. It is suggested that the heat-activation phenomenon could be explained by assuming that heat or reducing agents change the tertiary structure of a protein responsible for the maintenance of the dormant state by reducing the disulfide linkages which stabilize the protein in a specific configuration. The partial denaturation of this protein is reversible by reoxidation of the reduced disulfide-bonds.