How do spores germinate?

Abstract

Spore germination, as defined as those events that result in the loss of the spore‐specific properties, is an essentially biophysical process. It occurs without any need for new macromolecular synthesis, so the apparatus required is already present in the mature dormant spore. Germination in response to specific chemical nutrients requires specific receptor proteins, located at the inner membrane of the spore. After penetrating the outer layers of spore coat and cortex, germinant interacts with its receptor: one early consequence of this binding is the movement of monovalent cations from the spore core, followed by Ca2+ and dipicolinic acid (DPA). In some species, an ion transport protein is also required for these early stages. Early events – including loss of heat resistance, ion movements and partial rehydration of the spore core – can occur without cortex hydrolysis, although the latter is required for complete core rehydration and colony formation from a spore. In Bacillus subtilis two crucial cortex lytic enzymes have been identified: one is CwlJ, which is DPA‐responsive and is located at the cortex‐coat junction. The second, SleB, is present both in outer layers and at the inner spore membrane, and is more resistant to wet heat than is CwlJ. Cortex hydrolysis leads to the complete rehydration of the spore core, and then enzyme activity within the spore protoplast resumes. We do not yet know what activates SleB activity in the spore, and neither do we have any information at all on how the spore coat is degraded.

The Ger Receptor Family from Sporulating Bacteria

“…The spore's durability is even more remarkable considering that dormant spores revert back to actively growing cells almost immediately after nutrients return to the environment (Moir, 2006). The intrinsic resistance and the ability to remain dormant for long periods make spores the perfect delivery vehicle for infectious diseases.…”

“…This ultimately results in the loss of typical dormant spore properties . The mechanism of spore germination has been reviewed in detail elsewhere (Moir, 2006;Moir et al, 2002;Setlow, 2003).…”

“…In most cases, Ger receptor activation is the first committed step in the germination process (Moir, 2006;Moir et al, 2002). Ger receptors are encoded, in general, as tricistronic operons containing three protein-coding genes, the A-, B-, and C-subunits ( Figure 1) Setlow, 2003).…”

Coherent X-ray diffractive imaging on the single-cell-level of microbial samples

“…The full process ending in a free endospore takes about 7-8 hours in case of B. subtilis [180,229]. Vegetative growth is continued after germination of the endospore [205,230,272].…”

Quantitative Analysis of Spatial-Temporal Correlations during Germination of Spores of Bacillus Species

“…However, the dormant spores continually monitor their environment and can resume vegetative growth once the environment becomes suitable. The first step in a spore's return to growth is germination, which can be initiated by some specific nutrient germinant molecules, including amino acids, nucleosides, and sugars (16,27). A key early step in germination is the release of the spores' large pool (ϳ20% of the dry weight of spores' central region or core) of dipicolinic acid (DPA) that is chelated to divalent metal ions, predominantly Ca 2ϩ (Ca-DPA) (12,25,27).…”