Genomics and Cellular Biology of Endospore Formation
from: Bacillus: Cellular and Molecular Biology (Edited by: Peter Graumann). Caister Academic Press, U.K. (2007)
Bacteria of the genera Bacillus and Clostridium can be found in two distinct states. In the vegetative state, the bacterium is metabolically active and uses available nutrients to grow and divide by binary fission, a process that generates two identical daughter cells. By contrast, when nutrients are scarce, a developmental program of endospore formation (sporulation) is initiated, resulting in the production of a highly resistant spore. In the spore state, the bacterium is metabolically dormant, and its genetic material, protected in the core of the spore, can endure a variety of challenges, including radiation, heat and chemicals. Sporulation is a complex process, which requires the generation of two distinct cell types: a forespore and a larger mother cell. The progression of the developmental program is controlled by two exquisitely regulated cell type-specific lines of gene expression that run in parallel and are connected at the post-transcriptional level. Various genetic screens and genome-wide transcriptional analyses have identified more than 600 genes that are expressed in the course of sporulation. The function of several of these genes has been characterized in detail and subcellular localization data are available for more than 70 sporulation proteins. Thus, sporulation constitutes one of the best characterized developmental programs at the molecular and cellular levels read more ...