Germination of Bacillus stearothermophilus Spores1

FIELDS, AI. L. (University of MIissouri, Columbia), AND N. FINLEY. Effect of carbohydrates in phosphate buffer on germination of Bacillus stearothermophilus spores. Appl. l\Iicrobiol. 11: 453-457. 1963.-Among strains, and among spore suspensions of the same strain, different spore-germination responses were observed when spores were heated in monosaccharides, disaccharides, and polysaccharides in 0.0083 M phosphate buffer (pH 7.1). It was hypothesized that these differences were due to rough and smooth variants in the spore population and to variation in the osmosensitivity of spores of variants within the population when subjected to a heat shock of 110 C. Various workers have listed an energy source (glucose) and phosphate ions, singly or in combination, as being necessary for, or having an influence on, spore germination in certain species of the genus Bacillus (Heiligman, Desrosier, and Bromand, 1956; Desrosier and Heiligman, 1956; Knaysi, 1948; Powell, 1951; Church, Halvorson, and Halvorson, 1954; Curran and Knaysi, 1961). The influence of the combination of an energy source, phosphate, and heat on spore germination has not been reported for temperatures of 110 C. Previous studies in our laboratory indicated that 0.0083 M phosphate buffer had a suppressing effect on spore germination when the spores of Bacillus stearothe-mophilus were heated, at 110 C, at the maximal activation time in distilled water (Finley and Fields, 1962). Other research indicated that heating spores of B. stearothermophilus in carbohydrate solutions alone might produce inhibition or stimulation at 110 C (Fields and Finley, Food Technol., in press; unpublished data). Our particular interest in this research was to determine whether the inhibitory effect of phosphate on spore germination could be decreased by the presence of carbohydrates in the heating menstruum. Therefore, experiments were designed to determine whether the inhibitory effect of phosphate could be influenced by increased carbohydrate concentration, and to measure the influence of selected monosaccharides, disaccharides, and polysaccharides in phosphate buffer on heat-activation re-