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Encyclopedia > Bacteriocin

Bacteriocins are proteinaceous toxins produced by bacteria to inhibit the growth of similar bacterial strain(s). They are phenomenologically analagous to yeast and paramecium killing factors, and are structurally, functionally, and ecologically diverse. A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... A toxin, in a scientific context, is a biologically produced substance that causes injury to the health of a living thing on contact or absorption, typically by interacting with biological macromolecules such as enzymes and receptors. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ...


Bacteriocins were first discovered by Gratia in 1925. He was involved in the process of searching for ways to kill bacteria, which also resulted in the development of antibiotics and the discovery of bacteriophage, all within a span of a few years. He called his first discovery a colicine because it killed E. coli. An antibiotic is a drug that kills oops or slows the growth of bacteria. ... A phage (also called bacteriophage) (in Greek phageton = food/consumption) is a small virus that infects only bacteria. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ...


Bacteriocins are categorized in several ways, including producing strain, common resistance mechanisms, and mechanism of killing. There are several large categories of bacteriocin which are only phenomenologically related. These include the bacteriocins of gram + bacteria, the colicins, the microcins, and the bacteriocins of Archaea. Microcins are very small bacteriocins, composed of a relatively few peptides. ... Phyla / Classes Phylum Crenarchaeota Phylum Euryarchaeota     Halobacteria     Methanobacteria     Methanococci     Methanopyri     Archaeoglobi     Thermoplasmata     Thermococci Phylum Korarchaeota Phylum Nanoarchaeota The Archaea are a major group of prokaryotes. ...


E. coli bacteriocins are called colicins. They are the longest studied bacteriocins. They are a diverse group of bacteriocins and do not include all the bacteriocins produced by E. coli. In fact, one of the oldest known so-called colicins was called colicin V and is now know as microcin V. It is much smaller and produced and secreted in a different manner than the classic colicins. Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ... Binomial name Escherichia coli T. Escherich, 1885 Escherichia coli (usually abbreviated to E. coli) is one of the main species of bacteria that live in the lower intestines of warm-blooded animals (including birds and mammals) and are necessary for the proper digestion of food. ...


Virtually all colicins are carried on plasmids. There are two general classes of colicinogenic plasmids, large, low-copy number plasmids, and small high copy number plasmids. The larger plasmids carry other genes as well as the colicin operon. The colicin operons are generally organized with several major genes. These include an immunity gene, a colicin structural gene, and a BRP (bacteriocin release protein), or lysis, gene. The immunity gene is often produced constitutively, while the BRP is generally produced only as a read-through of the stop codon on the colicin structural gene. The colicin itself is repressed by the SOS system and may be regulated in other ways as well. Figure 1 : Schematic drawing of a bacterium with plasmids enclosed. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... Lysis (Greek lusis from luein = to separate) is the reduction of symptoms of a disease the dissolving of cells osmotic lysis chemical lysis viral lysis a dialogue of Plato about friendship (philia) This is a disambiguation page — a navigational aid which lists other pages that might otherwise share the same... RNA codons. ...


Research indicates that retaining the colicin plasmid is very important for cells that live with their relatives, because if a cell loses the immunity gene, it quickly becomes subject to destruction by circulating colicin. At the same time, colicin is only released from a producing cell by the use of the lysis protein, which results in that cell's death. This suicidal production mechanism would appear to be very costly, except for the fact that it is regulated by the SOS system, which responds to significant DNA damage. In short, colicin production may only occur in terminally-ill cells. Still these matters require further research. Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) or deoxyribose nucleic acid is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and many viruses). ...


The colicins themselves are composed of three globular domains. One domain regulates the target and binds to the receptor on the sensitive cell. The second is involved with translocation, co-opting the machinery of the target cell. The third is the 'killing' domain and may produce a pore in the target cell membrane, or act as a nuclease to chop up the DNA or RNA of the target cell. Because they target specific receptors and use specific translocation machinery, cells can make themselves resistant to the colicin by repressing or deleting the genes for these proteins. Such resistant cells may suffer the lack of a key nutrient (such as iron or vitamin B) but benefit by not being killed. Colicins exhibit a '1-hit killing kinetic' which doesn't necessarily mean a single molecule is sufficient to kill, but certainly that it only takes a small number. In his Nobel Laureate speech, Salvador E. Luria, 1969, speculated that colicins could only be this toxic by causing a domino effect that destabilized the cell membrane. He was not entirely correct, but pore-forming colicins do de-polarize the membrane and thus eliminate the energy source for the cell. The colicins are highly effective toxins. Salvador Edward Luria (August 13, 1912 - February 6, 1991) was a naturalized American microbiologist whose pioneering work on phage helped open up molecular biology. ... A toxin, in a scientific context, is a biologically produced substance that causes injury to the health of a living thing on contact or absorption, typically by interacting with biological macromolecules such as enzymes and receptors. ...


The bacteriocins of lactic acid-fermenting bacteria are well studied because of the commercial use of these bacteria in the food industry for making dairy products such as cheese. Bacteriocins are classified according to their extent of posttranslational modification. The lantibiotics are a class of more extensively modified bacteriocins, also called Class I. Bacteriocins for which disulfide bonds are the only modification to the peptide are Class II bacteriocins. Most bacteriocins are biologically active single-chain peptides. Some are only active as partners with a second peptide (see Class IIb, below). Lactic acid (α-hydroxypropionic acid) is a chemical compound that plays a role in several biochemical processes. ... Cheese is a solid food made from the curdled milk of various animals—most commonly cows but sometimes goats, sheep, reindeer, and water buffalo. ... Posttranslational modification means the chemical modification of a protein after its translation. ... Lantibiotics are polycyclic peptides containing the uncommon amino acids lanthionine and unsaturated amino acids such as dehydroalanine. ... A disulfide bond (SS-bond), also called a disulfide bridge, is a strong covalent bond between two sulfhydryl groups. ...


Nisin and epidermin are members of a family of lantibiotics that bind to a cell wall precursor lipid component of target bacteria and disrupt cell wall production. The duramycin family of lantibiotics binds phosphoethanolamine in the membranes of its target cells and seem to disrupt several physiological functions. Nisin is an inhibitory polycyclic peptide with 34 amino acid residues used as a food preservative. ... A cell wall is a more or less solid layer surrounding a cell. ...


The action of Class IIa bacteriocins seems to involve disruption of mannose transport into target cells. Class IIb bacteriocins form pores in the membranes of target cells and disrupt the proton gradient of target cells. Other bacteriocins can be grouped together as Class IIc. These have a wide range of effects on membrane permeability, cell wall formation and pheromone actions of target cells. Mannose is a sugar, one of the hexose series of carbohydrates. ... The Chemiosmotic Hypothesis is the proposal in 1961, by Peter D. Mitchell, that the mitochondrion functioned as a kind of electrochemical capacitor, using the energy of NADH and FADH2 to create a proton gradient across the mitochondrial membrane and that this energy was used by a reversible proton pump, the... A cell wall is a more or less solid layer surrounding a cell. ... Fanning honeybee exposes Nasonov gland (white-at tip of abdomen) releasing pheromone to entice swarm into an empty hive A pheromone is any chemical produced by a living organism that transmits a message to other members of the same species. ...


Bacteriocins are of interest in medicine because they are made by non-pathogenic bacteria that normally colonize the human body. Loss of these harmless bacteria following antibiotic use may allow oportunistic pathogenic bacteria to invade the human body. A pathogen (literally birth of pain from the Greek παθογένεια) is a biological agent that can cause disease to its host. ... An antibiotic is a drug that kills oops or slows the growth of bacteria. ...


There are many ways to demonstrate bacteriocin production, depending on the sensitivity and labor intensiveness desired. To demonstrate their production, technicians stab inoculate multiple strains on separate multiple nutrient agar Petri dishes, incubate at 30 °C for 24 h., overlay each plate with one of the strains (in soft agar), incubate again at 30 °C for 24 h. After this process, the presence of bacteriocins can be inferred if there are zones of growth inhibition around stabs. This is the simplest and least sensitive. It will often mistake phage for bacteriocins. Some methods prompt production with UV radiation, Mitomycin C, or heat shock. Cross streaking may be substituted for lawns. Similarly, production in broth may be followed by dripping the broth on a nascent bacterial lawn, or even filtering it. Precipitation (ammonia sulfate) and some purification (e.g. column or HPLC) may help exclude lysogenic and lytic phage from the assay. Agar is a galactose polymer (or Agarose) obtained from the cell walls of some species of red algae or seaweed (Sphaerococcus euchema) and species of Gelidium, chiefly from eastern Asia and California. ... Man looking at fungus inside of petri dishes A Petri dish is a shallow glass or plastic cylindrical dish that biologists use to culture microbes. ... Strain, in any branch of science dealing with materials and their behaviour, is the geometrical expression of deformation caused by the action of stress on a physical body. ...


  Results from FactBites:
 
Bacteriocin - Wikipedia, the free encyclopedia (952 words)
Bacteriocins are proteinaceous toxins produced by bacteria to inhibit the growth of similar bacterial strain(s).
Bacteriocins are classified according to their extent of posttranslational modification.
Bacteriocins are of interest in medicine because they are made by non-pathogenic bacteria that normally colonize the human body.
  More results at FactBites »

 
 

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