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An endospore is a dormant, tough, and non-reproductive structure produced by some bacteria in the phylum Bacillota. [1] [2] The name "endospore" is suggestive of a spore or seed-like form (endo means 'within'), but it is not a true spore (i.e., not an offspring). It is a stripped-down, dormant form to which the bacterium can reduce itself.
Many bacteria can survive adverse conditions such as temperature, desiccation, and antibiotics by forming endospores, cysts, or general states of reduced metabolic activity lacking specialized cellular structures. [15] Up to 80% of the bacteria in samples from the wild appear to be metabolically inactive [16] —many of which can be ...
Yet, some scientists have also raised concerns about the possibility that some metabolically dormant bacteria and protists, as well as always metabolically inactive viruses, may both survive the thaw and either threaten humans directly, or affect some of the animal or plant species important for human wellbeing.
Various members of the Azotobacteraceae family have been shown to survive in an encysted form for up to 24 years. The extremophile Rhodospirillum centenum, an anoxygenic, photosynthetic, nitrogen-fixing bacterium that grows in hot springs was found to form cysts in response to desiccation as well. [12] Bacteria do not always form a single cyst.
Clostridium species are endospore-forming bacteria, and can survive in atmospheric concentrations of oxygen in this dormant form. The remaining bacteria listed do not form endospores. [5] Several species of the Mycobacterium, Streptomyces, and Rhodococcus genera are examples of obligate anaerobe found in soil. [10]
The cells do not reproduce in synchrony without explicit and continual prompting (as in experiments with stalked bacteria [9]) and their exponential phase growth is often not ever a constant rate, but instead a slowly decaying rate, a constant stochastic response to pressures both to reproduce and to go dormant in the face of declining nutrient ...
Bacteria can survive under diverse environmental conditions and in order to overcome these adverse and changing conditions, bacteria must sense the changes and mount appropriate responses in gene expression and protein activity. The stress response in bacteria involves a complex network of elements that counteracts the external stimulus.
Anhydrobiosis in the tardigrade Richtersius coronifer. Anhydrobiosis is the most studied form of cryptobiosis and occurs in situations of extreme desiccation.The term anhydrobiosis derives from the Greek for "life without water" and is most commonly used for the desiccation tolerance observed in certain invertebrate animals such as bdelloid rotifers, tardigrades, brine shrimp, nematodes, and ...