What is "escherichia coli"

Indole \In"dole\, Indol \In"dol\([i^]n"d[=o]l), n. [Indigo + -ol of phenol.] (Chem., Physiol. Chem.) A white, crystalline substance, C8H7N, obtained from blue indigo, and almost all indigo derivatives, by a process of reduction; chemically, it is 2,3-benzopyrrole, a bicyclic heterocyclic compound, having a benzene ring fused to a pyrrole ring. It is also formed from proteinaceous matter, together with skatol, by putrefaction, and by fusion with caustic potash, and is present in human excrement, as well as in the intestinal canal of some herbivora. It is produced in rich growth media by the intestinal bacterium Escherichia coli.

Exponential \Ex`po*nen"tial\, a. [Cf. F. exponentiel.]

1. Pertaining to exponents; involving variable exponents; as, an exponential expression; exponential calculus; an exponential function.

2. changing over time in an exponential manner, i. e. increasing or decreasing by a fixed ratio for each unit of time; as, exponential growth; exponential decay.

   Note:

   Exponential growth is characteristic of bacteria and other living populations in circumstances where the conditions of growth are favorable, and all required nutrients are plentiful. For example, the bacterium Escherichia coli in rich media may double in number every 20 minutes until one of the nutrients becomes exhausted or waste products begin to inhibit growth. Many fascinating thought experiments are proposed on the theme of exponential growth. One may calculate, for example how long it would take the progeny of one Escherichia coli to equal the mass of the known universe if it multiplied unimpeded at such a rate. The answer, assuming the equivalent of 10^ 80 hydrogen atoms in the universe, is less than three days. Exponential increases in a quantity can be surprising, and this principle is often used by banks to make investment at a certain rate of interest seem to be very profitable over time.

   Exponential decay is exhibited by decay of radioactive materials and some chemical reactions (first order reactions), in which one-half of the initial quantity of radioactive element (or chemical substance) is lost for each lapse of a characteristic time called the half-life.

   Exponential curve, a curve whose nature is defined by means of an exponential equation.

   Exponential equation, an equation which contains an exponential quantity, or in which the unknown quantity enters as an exponent.

   Exponential quantity (Math.), a quantity whose exponent is unknown or variable, as a^ x.

   Exponential series, a series derived from the development of exponential equations or quantities.

Escherichia coli (; also known as E. coli) is a gram-negative, facultatively anaerobic, rod-shaped bacterium of the genus Escherichia that is commonly found in the lower intestine of warm-blooded organisms (endotherms). Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in their hosts, and are occasionally responsible for product recalls due to food contamination. The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K, and preventing colonization of the intestine with pathogenic bacteria. E. coli is expelled into the environment within fecal matter. The bacterium grows massively in fresh fecal matter under aerobic conditions for 3 days, but its numbers decline slowly afterwards.

E. coli and other facultative anaerobes constitute about 0.1% of gut flora, and fecal–oral transmission is the major route through which pathogenic strains of the bacterium cause disease. Cells are able to survive outside the body for a limited amount of time, which makes them potential indicator organisms to test environmental samples for fecal contamination. A growing body of research, though, has examined environmentally persistent E. coli which can survive for extended periods outside of a host.

The bacterium can be grown and cultured easily and inexpensively in a laboratory setting, and has been intensively investigated for over 60 years. E. coli is a chemoheterotroph whose chemically defined medium must include a source of carbon and energy. Organic growth factors included in chemically defined medium used to grow E. coli includes glucose, ammonium phosphate, mono basic, sodium chloride, magnesium sulfate, potassium phosphate, dibasic, and water. The exact chemical composition is known for media that is considered chemically defined medium. E. coli is the most widely studied prokaryotic model organism, and an important species in the fields of biotechnology and microbiology, where it has served as the host organism for the majority of work with recombinant DNA. Under favorable conditions, it takes only 20 minutes to reproduce.

Escherichia coli (; commonly abbreviated E. coli) is a Gram negative gammaproteobacterium commonly found in the lower intestine of warm-blooded organisms (endotherms). The descendants of two isolates, K-12 and B strain, are used routinely in molecular biology as both a tool and a model organism.