EFFECT OF SPORULATION MEDIUM ON HEAT RESISTANCE, CHEMICAL COMPOSITION, AND GERMINATION OF BACILLUS MEGATERIUM SPORES1

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Levinson, Hillel S. (U.S. Army Natick Laboratories, Natick, Mass.), and Mildred T. Hyatt. Effect of sporulation medium on heat resistance, chemical composition, and germination of Bacillus megaterium spores. J. Bacteriol. 87:876–886. 1964.—Bacillus megaterium spores, grown on variously supplemented media, had varying concentrations of P, Ca, Mn, or dipicolinic acid. Supplementation with CaCl2 yielded spores with increased heat resistance; addition of l-glutamate, l-proline, or increase of the phosphate concentration yielded spores with reduced heat resistance. Germination characteristics depended on both the sporulation medium and the germinant (glucose, l-alanine, l-leucine, or KNO3); pronounced differences were demonstrable with glucose and l-alanine, which trigger germination via different metabolic pathways. An increase in CaCl2 during sporulation yielded spores with increased germination in glucose but not in l-alanine. Germination in l-alanine was optimal with spores produced on media containing 0.1 mm MnCl2, but germination of such spores was minimal in glucose. An increase in the sporulation medium phosphate decreased the initial germination rate in glucose, but not in l-alanine. Spores produced in CaCl2-supplemented media had increased heat-activation requirements (increased dormancy) for germination induced by l-alanine, and decreased heat-shock requirements for glucose-induced germination. An increase of sporulation phosphate yielded spores with reduced dormancy for germination induced by l-alanine, but with unchanged dormancy on the other germinants. Spores produced with added l-glutamate had reduced dormancy for glucose-induced germination, and increased dormancy for germination induced by l-alanine. Addition of CaCl2 or l-glutamate to the sporulation medium yielded spores with increased sensitivity to “ionic germination” (with KI). Spores from synthetic medium were incapacitated for full postgerminative development, as shown by repression of the changes in oxygen-uptake rate which accompany normal cell division.

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