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Encyclopedia > Endospore

An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute family. The primary function of most endospores is to ensure the survival of a bacterium through periods of environmental stress. They are therefore resistant to ultraviolet and gamma radiation, desiccation, lysozyme, temperature, starvation, and chemical disinfectants. Endospores are commonly found in soil and water, where they may survive for long periods of time. Some bacteria produce exospores or cysts instead. Dormancy is a arrested plant growth. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... Classes Bacilli Clostridia Mollicutes The Firmicutes are a group of bacteria, most of which have Gram-positive stains. ... Note: Ultraviolet is also the name of a 1998 UK television miniseries about vampires. ... This article is about electromagnetic radiation. ... Desiccation is the state of extreme dryness, or the process of extreme drying. ... Lysozyme 3D structure. ... Fig. ... A female child during the Nigerian-Biafran war of the late 1960s, shown suffering the effects of severe hunger and malnutrition. ... Disinfection The destruction of pathogenic and other kinds of microorganisms by physical or chemical means Disinfectants are chemical substances used to kill viruses and microbes (germs), such as bacteria and fungi. ... This article or section does not cite its references or sources. ...

Variations in endospore morphology. (1, 4) Central endospore, (2, 3, 5) terminal endospore, (6) lateral endospore
Variations in endospore morphology. (1, 4) Central endospore, (2, 3, 5) terminal endospore, (6) lateral endospore

Contents

Image File history File links Bakterien_Sporen. ... Image File history File links Bakterien_Sporen. ...

Structure

In contrast to eukaryotic spores, which are produced by many eukaryotes for reproductive purposes, bacteria will produce a single endospore internally. The spore is often surrounded by a thin covering known as the exosporium, which overlies the spore coat. The spore coat is impermeable to many toxic molecules and may also contain enzymes that are involved in germination. The cortex lies beneath the spore coat and consists of peptidoglycan. The core wall lies beneath the cortex and surrounds the protoplast or core of the endospore. The core has normal cell structures, such as DNA and ribosomes, but is metabolically inactive. This article is about a biological reproductive structure; for the video game, see Spore (video game). ... Kingdoms Animalia - Animals Fungi Plantae - Plants Protista Alternative Phylogeny Unikonta    Opisthokonta    Amoebozoa Bikonta    Apusozoa    Cabozoa       Rhizaria       Excavata    Corticata       Archaeplastida       Chromalveolata Animals, plants, fungi, and protists are eukaryotes (IPA: ), organisms with a complex cell or cells, where the genetic material is organized into a membrane-bound nucleus or nuclei. ... In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. ... Neuraminidase ribbon diagram An enzyme (in Greek en = in and zyme = blend) is a protein, or protein complex, that catalyzes a chemical reaction and also controls the 3D orientation of the catalyzed substrates. ... Peptidoglycan, also known as murein, is a substance that forms a homogeneous layer lying outside the plasma membrane in bacteria. ... Initially protoplast (in Greek: proton = first and platho = mould) referred to the first organized body of a species this meaning is similar to the non-biological definition, the first from from which all subsequent forms are derived. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ...


Up to 15% of the dry weight of the endospore consists of calcium dipicolinate within the core, which is thought to stabilize the DNA. Dipicolinic acid could be responsible for the heat resistance of the spore, and calcium may aid in resistance to heat and oxidizing agents. However, mutants resistant to heat but lacking dipicolinic acid have been isolated, suggesting other mechanisms contributing to heat resistance are at work[1]. The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Standard atomic weight 40. ...


Location

The position of the endospore differs among bacterial species and is useful in identification. The main types within the cell are terminal, subterminal and centrally placed endospores. Terminal endospores are seen at the poles of cells, whereas central endospores are more or less in the middle. Subterminal endospores are those between these two extremes, usually seen far enough towards the poles but close enough to the center so as not to be considered either terminal or central. Lateral endospores are seen occasionally.


Examples of bacteria having terminal endospores include Clostridium tetani, the pathogen which causes the disease tetanus. Bacteria having a centrally placed endospore include Bacillus cereus, and those having a subterminal endospore include Bacillus subtilis. Sometimes the endospore can be so large the cell can be distended around the endospore, this is typical of Clostridium tetani. Binomial name Clostridium tetani Flügge, 1886 Clostridium tetani is a rod-shaped, anaerobic bacterium of the genus Clostridium. ... Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. ... Binomial name Bacillus cereus Frankland & Frankland 1887 Bacillus cereus is an endemic, soil-dwelling, Gram-positive, rod shaped, beta hemolytic bacteria that causes foodborne illness. ... Binomial name Bacillus subtilis (Ehrenberg 1835) Cohn 1872 Gram-stained Bacillus subtilis Sporulating Bacillus subtilis Bacillus subtilis is a Gram-positive, catalase-positive bacterium commonly found in soil. ...


Visualising endospores under the light microscope can be difficult due to the impermeability of the endospore wall to dyes and stains. While the rest of a bacterial cell may stain, the endospore is left colourless. To combat this, a special stain technique called a Moeller stain is used. That allows the endospore to show up as red, while the rest of the cell stains blue. Another staining technique for endospores is the Schaffer-Fulton stain, which stains endospores green and bacterial bodies red.


Formation and destruction

A stained preparation of Bacillus subtilis showing endospores as green and the vegetative cell as red
A stained preparation of Bacillus subtilis showing endospores as green and the vegetative cell as red

When a bacterium detects environmental conditions are becoming unfavourable it may start the process of sporulation, which takes about eight hours. The DNA is replicated and a membrane wall known as a spore septum begins to form between it and the rest of the cell. The plasma membrane of the cell surrounds this wall and pinches off to leave a double membrane around the DNA, and the developing structure is now known as a forespore. Calcium dipicolinate is incorporated into the forespore during this time. Next the peptidoglycan cortex forms between the two layers and the bacterium adds a spore coat to the outside of the forespore. Sporulation is now complete, and the mature endospore will be released when the surrounding vegetative cell is degraded. Image File history File links Bacillus_subtilis_Spore. ... Image File history File links Bacillus_subtilis_Spore. ... Binomial name Bacillus subtilis (Ehrenberg 1835) Cohn 1872 Gram-stained Bacillus subtilis Sporulating Bacillus subtilis Bacillus subtilis is a Gram-positive, catalase-positive bacterium commonly found in soil. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... Look up septum in Wiktionary, the free dictionary. ... Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ...


Endospores are resistant to most agents which would normally kill the vegetative cells they formed from. Household cleaning products generally have no effect, nor do most alcohols, quaternary ammonium compounds or detergents. Alkylating agents however, such as ethylene oxide, are effective against endospores. In general usage, alcohol (from Arabic al-khwl الكحول, or al-ghawl الغول) refers almost always to ethanol, also known as grain alcohol, and often to any beverage that contains ethanol (see alcoholic beverage). ... Quaternary ammonium cation. ... A detergent is a compound, or a mixture of compounds, intended to assist cleaning. ... Alkylation is the transfer of an alkyl group from one molecule to another. ... The chemical compound ethylene oxide is an important industrial chemical used as an intermediate in the production of ethylene glycol and other chemicals, and as a sterilant for foodstuffs and medical supplies. ...


Whilst resistant to extreme heat and radiation, endospores can be destroyed by burning or autoclaving. Exposure to extreme heat for a long enough period will generally have some effect, though many endospores can survive hours of boiling or cooking. Prolonged exposure to high energy radiation, such as xrays and gamma rays, will also kill most endospores. Front loading autoclaves are common Stovetop autoclaves need to be monitored carefully, but have a very large capacity Multiple large autoclaves are used for processing substantial quantities of laboratory equipment prior to reuse, and infectious material prior to disposal. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... This article is about electromagnetic radiation. ...


Reactivation

Reactivation of the endospore occurs when conditions are more favourable and involves activation, germination, and outgrowth. Even if an endospore is located in plentiful nutrients, it may fail to germinate unless activation has taken place. This may be triggered by heating the endospore. Germination involves the dormant endospore starting metabolic activity and thus breaking hibernation. It is commonly characterised by rupture or absorption of the spore coat, swelling of the endospore, an increase in metabolic activity, and loss of resistance to environmental stress. Outgrowth proceeds germination and involves the core of the endospore manufacturing new chemical components and exiting the old spore coat to develop into a fully functional vegetative bacterial cell, which can divide to produce more cells.


Importance

As a simplified model for cellular differentiation, the molecular details of endospore formation have been extensively studied, especially in the model organism Bacillus subtilis. These studies have contributed much to our understanding of the regulation of gene expression, transcription factors, and the sigma factor subunits of RNA polymerase. Embryonic stem cells differentiate into cells in various body organs. ... A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. ... Binomial name Bacillus subtilis (Ehrenberg 1835) Cohn 1872 Gram-stained Bacillus subtilis Sporulating Bacillus subtilis Bacillus subtilis is a Gram-positive, catalase-positive bacterium commonly found in soil. ... Gene expression, or simply expression, is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ... In molecular biology, a transcription factor is a protein that binds DNA at a specific promoter or enhancer region or site, where it regulates transcription. ... Sigma factor (σ factor) is a prokaryotic initiation factor that binds to RNA polymerase and promotes attachment to promoter sites on DNA. There are seven different sigma factors for different kinds of promoters. ... RNAP from pictured during elongation. ...


Endospores of the bacterium Bacillus anthracis were used in the 2001 anthrax attacks. The powder found in contaminated postal letters was composed of extracellular anthrax endospores. Inhalation, ingestion or skin contamination of these endospores, which were technically incorrectly labelled as "spores", led to a number of deaths. Binomial name Bacillus anthracis Cohn 1872 Bacillus anthracis is a Gram-positive, facultatively anaerobic, rod-shaped bacterium of the genus Bacillus. ... The 2001 anthrax attacks in the United States, also known as Amerithrax from its FBI case name, occurred over the course of several weeks beginning on September 18, 2001 (a week after the September 11, 2001 attacks). ...


Endospore-forming bacteria

Examples of endospore-forming bacteria include the genera:

Species Bacillus anthracis Bacillus cereus Bacillus coagulans Bacillus natto Bacillus subtilis Bacillus thuringiensis etc. ... Species Clostridium acetobutylicum Clostridium aerotolerans Clostridium botulinum Clostridium colicanis Clostridium difficile Clostridium formicaceticum Clostridium novyi Clostridium perfringens Clostridium sordelli Clostridium tetani Clostridium piliforme Clostridium tyrobutyricum etc. ... Desulfotomaculum is a genus of Gram-positive, obligately anaerobic soil bacteria. ...

References

  1. ^ Prescott, L. (1993). Microbiology, Wm. C. Brown Publishers, ISBN 0-697-01372-3.

External links

Wikimedia Commons has media related to:
Endospore
  • Endospore structure
  • Microbial Spore Formation
  • Endospore Structure

  Results from FactBites:
 
ScienceDaily: Endospore (1456 words)
An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute family.
Endospores are commonly found in soil and water, where they may survive for long periods of time.
Endospore -- An endospore is a dormant, tough, non-reproductive structure produced by a small number of bacteria from the Firmicute family.
The Microbial World :: They rule (671 words)
Endospores are refractile - light cannot penetrate them so that they are very easy to see in the phase microscope and this makes it easy to detect them.
Endospores that were dormant for thousands of years in the great tombs of the Egyptian pharohs were able to germinate and grow when placed in appropriate medium.
Endospores enable a species to spread eaily from one suitable environment to antoher an many endospore-forming bacteria are ubiquitous in the environment.
  More results at FactBites »

 
 

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