''Escherichia'' ( ) is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
Gram-negative
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ...
, non-
spore
In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...
-forming,
facultatively anaerobic, rod-shaped
bacteria
Bacteria (; : bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of Prokaryote, prokaryotic microorganisms. Typically a few micr ...
from the family
Enterobacteriaceae.
In those species which are inhabitants of the
gastrointestinal tract
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the Digestion, digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascula ...
s of
warm-blooded
Warm-blooded is a term referring to animal species whose bodies maintain a temperature higher than that of their environment. In particular, homeothermic species (including birds and mammals) maintain a stable body temperature by regulating ...
animals, ''Escherichia'' species provide a portion of the microbially derived
vitamin K
Vitamin K is a family of structurally similar, fat-soluble vitamers found in foods and marketed as dietary supplements. The human body requires vitamin K for post-translational modification, post-synthesis modification of certain proteins ...
for their host. A number of the species of ''Escherichia'' are
pathogen
In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
ic. The genus is named after
Theodor Escherich, the discoverer of ''
Escherichia coli
''Escherichia coli'' ( )Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. is a gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Escherichia'' that is commonly fo ...
''. ''Escherichia'' are facultative aerobes, with both aerobic and anaerobic growth, and an optimum temperature of 37 °C.
''Escherichia'' are usually motile by
flagella
A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...
, produce gas from fermentable carbohydrates, and do not decarboxylate
lysine or hydrolyze
arginine
Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidinium, guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) a ...
.
Species include ''
E. albertii'', ''
E. fergusonii'', ''
E. hermannii'', ''
E. ruysiae'', ''
E. marmotae'' and most notably, the
model organism
A model organism is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. Mo ...
and clinically relevant ''
E. coli''. Formerly, ''
Shimwellia blattae''
and
Pseudescherichia vulneris were also classified in this genus.
Pathogenesis
While many ''Escherichia'' are commensal members of the
gut microbiota, certain strains of some species, most notably the
pathogenic serotypes of ''
E. coli'', are human pathogens,
and are the most common cause of
urinary tract infections,
significant sources of gastrointestinal disease, ranging from simple
diarrhea
Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...
to
dysentery
Dysentery ( , ), historically known as the bloody flux, is a type of gastroenteritis that results in bloody diarrhea. Other symptoms may include fever, abdominal pain, and a feeling of incomplete defecation. Complications may include dehyd ...
-like conditions,
as well as a wide range of other pathogenic states
classifiable in general as colonic escherichiosis. While ''E. coli'' is responsible for the vast majority of ''Escherichia''-related pathogenesis, other members of the genus have also been implicated in human disease.
''Escherichia'' are associated with the imbalance of
microbiota of the lower reproductive tract of women. These species are associated with inflammation.
See also
*
''E. coli'' O157:H7
*
List of bacterial genera named after personal names
References
External links
Escherichiagenomes and related information a
PATRIC a Bioinformatics Resource Center funded b
NIAID
{{Authority control
Gut flora bacteria
Gram-negative bacteria
Pathogenic bacteria
Bacteria genera