![]() Notably, under suitable environmental conditions, primarily the presence of nutrients, spores germinate and then outgrow into vegetative bacteria which are capable of reproduction 5. These features are all major reasons for spore’s dormancy and extreme resistance 3. Unique features of the central core and the core membrane (CM) include: i) a low water content, as low as 25% of wet weight for spores in water ii) high core levels, ~25% of core dry weight, of a 1:1 chelate of Ca 2+ and dipicolinic acid (CaDPA) iii) DNA stabilisation by novel spore-specific proteins and iv) a relatively impermeable CM. During sporulation an outer membrane is formed and localized between the developing cortex and coat, but it is unclear if it persists in the mature spore 1. 1), which contains spore DNA, RNA and most spore enzymes 3. A multi-layered coat and a cortex layer surround the membrane-bound core 4 (Fig. The novel architecture and molecular composition of the spore provides resistance against extreme stresses (e.g. In pathogenic species, like Bacillus anthracis or Clostridioides difficile, the spore stage often plays a major role in transmission, infection or outbreak of the associated disease 2. Investigations of spores from different species suggest that these intracellular membrane structures below the core membrane are a general feature of endospore forming bacteria.īacteria of the classes Bacilli and Clostridia form endospores to survive harsh environmental conditions such as lack of nutrients 1. These intracellular membranes are most probably present as more or less compressed vesicles or tubules within the dormant spore core. During spore germination these internal core membranes disappear when the core size increases, suggesting that they are integrated into the core membrane to allow core expansion. In the current work, we demonstrate the presence of intracellular membrane structures in spores located just below the core membrane. ![]() To date, it has been unclear how the ~1.3- to 1.6-fold expansion of the core membrane surface area that accompanies core expansion takes place, since this occurs in the absence of significant if any ATP synthesis. One of these events is the expansion of the central spore core, which contains the DNA, RNA and most spore enzymes. ![]() The underlying processes of this latter physiological and morphological transformation involve a number of different events, some of which are mechanistically not entirely understood. Another remarkable spore feature is their rapid return to vegetative growth during spore germination and outgrowth. The spores possess a particular architecture and molecular inventory which endow them with a remarkable resistance against desiccation, heat and radiation. Bacterial endospores are formed by certain bacteria, such as Bacillus subtilis or the pathogenic Bacillus anthracis and Clostridioides difficile, to allow survival in environmental conditions which are lethal to vegetative bacteria.
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