Sporulation and Germination

Abstract

Since the 1950s bacterial sporulation in Bacillus has been recognized as a model system for analyzing differentiation in a prokaryotic organism. Earlier studies focused on the physiological and morphological changes which occurred during conversion of the vegetative cell into a heat-resistant, dormant spore. The physiological and morphological studies were complemented by the isolation of mutants which developed up to specific recognizable stages and were blocked in further development. However, the nature of spore-forming bacteria and the absence of suitable genetic and technical approaches precluded the precise analysis of the regulatory mechanisms which controlled sporulation. It was not possible to determine (1) which events regulated the initiation of sporulation, (2) what products were encoded by the sporulation and germination genes, (3) how genes were expressed in a temporally regulated fashion, (4) what the relationship was between catabolite repression and the initiation of sporulation, (5) what temporally regulated genes were essential for sporulation, (6) what transcriptional mechanism was required for the expression of sporulation genes, and (7) how the morphologically complex spore structure was assembled.