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Escherichia coli 대표 이미지

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Bacillus coli communis Escherich 1885 Escherichia coli (/ˌɛʃɨˈrɪkiə ˈkoʊlaɪ/;[1] 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).[2] 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.[3][4] The harmless strains are part of the normal flora of the gut, and can benefit their hosts by producing vitamin K2,[5] and preventing colonization of the intestine with pathogenic bacteria.[6][7] E. coli and other facultative anaerobes constitute about 0.1% of gut flora,[8] 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.[9][10] A growing body of research, though, has examined environmentally persistent E. coli which can survive for extended periods outside of a host.[11] 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 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 favourable conditions, it takes only 20 minutes to reproduce.[12] E. coli is a Gram-negative (bacteria which do not retain crystal violet dye), facultative anaerobic (that makes ATP by aerobic respiration if oxygen is present, but is capable of switching to fermentation or anaerobic respiration if oxygen is absent) and nonsporulating bacteria.[13] Cells are typically rod-shaped, and are about 2.0 micrometers (μm) long and 0.25–1.0 μm in diameter, with a cell volume of 0.6–0.7 μm3.[14][15] It can live on a wide variety of substrates. E. coli uses mixed-acid fermentation in anaerobic conditions, producing lactate, succinate, ethanol, acetate, and carbon dioxide. Since many pathways in mixed-acid fermentation produce hydrogen gas, these pathways require the levels of hydrogen to be low, as is the case when E. coli lives together with hydrogen-consuming organisms, such as methanogens or sulphate-reducing bacteria.[16] Optimal growth of E. coli occurs at 37 °C (98.6 °F), but some laboratory strains can multiply at temperatures of up to 49 °C.[17] Growth can be driven by aerobic or anaerobic respiration, using a large variety of redox pairs, including the oxidation of pyruvic acid, formic acid, hydrogen, and amino acids, and the reduction of substrates such as oxygen, nitrate, fumarate, dimethyl sulfoxide, and trimethylamine N-oxide.[18] Strains that possess flagella are motile. The flagella have a peritrichous arrangement.[19] E. coli and related bacteria possess the ability to transfer DNA via bacterial conjugation, transduction or transformation, which allows genetic material to spread horizontally through an existing population. This process led to the spread of the gene encoding Shiga toxin from Shigella to E. coli O157:H7, carried by a bacteriophage.[20] Escherichia coli encompasses an enormous population of bacteria that exhibit a very high degree of both genetic and phenotypic diversity. Genome sequencing of a large number of isolates of E. coli and related bacteria shows that a taxonomic reclassification would be desirable. However, this has not been done, largely due to its medical importance,[21] and E. coli remains one of the most diverse bacterial species: only 20% of the genome is common to all strains.[22] In fact, from the evolutionary point of view, the members of genus Shigella (S. dysenteriae, S. flexneri, S. boydii, and S. sonnei) should be classified as E. coli strains, a phenomenon termed taxa in disguise.[23] Similarly, other strains of E. coli (e.g. the K-12 strain commonly used in recombinant DNA work) are sufficiently different that they would merit reclassification. A strain is a subgroup within the species that has unique characteristics that distinguish it from other strains. These differences are often detectable only at the molecular level; however, they may result in changes to the physiology or lifecycle of the bacterium. For example, a strain may gain pathogenic capacity, the ability to use a unique carbon source, the ability to take upon a particular ecological niche, or the ability to resist antimicrobial agents. Different strains of E. coli are often host-specific, making it possible to determine the source of fecal contamination in environmental samples.[9][10] For example, knowing which E. coli strains are present in a water sample allows researchers to make assumptions about whether the contamination originated from a human, another mammal, or a bird. A common subdivision system of E. coli, but not based on evolutionary relatedness, is by serotype, which is based on major surface antigens (O antigen: part of lipopolysaccharide layer; H: flagellin; K antigen: capsule), e.g. O157:H7).[24] It is, however, common to cite only the serogroup, i.e. the O-antigen. At present, about 190 serogroups are known.[25] The common laboratory strain has a mutation that prevents the formation of an O-antigen and is thus not typeable. Like all lifeforms, new strains of E. coli evolve through the natural biological processes of mutation, gene duplication, and horizontal gene transfer; in particular, 18% of the genome of the laboratory strain MG1655 was horizontally acquired since the divergence from Salmonella.[26] E. coli K-12 and E. coli B strains are the most frequently used varieties for laboratory purposes. Some strains develop traits that can be harmful to a host animal. These virulent strains typically cause a bout of diarrhea that is unpleasant in healthy adults and is often lethal to children in the developing world.[27] More virulent strains, such as O157:H7, cause serious illness or death in the elderly, the very young, or the immunocompromised.[6][27] The genera Escherichia and Salmonella diverged around 102 million years ago (credibility interval: 57–176 mya) which coincides with the divergence of their hosts: the former being found in mammals and the latter in birds and reptiles.[28] This was followed by a split of the escherichian ancestor into five species (E. albertii, E. coli, E. fergusonii, E. hermannii, and E. vulneris). The last E. coli ancestor split between 20 and 30 million years ago.[29] The long-term evolution experiments using E. coli, begun by Richard Lenski in 1988, have allowed direct observation of major evolutionary shifts in the laboratory.[30] In this experiment, one population of E. coli unexpectedly evolved the ability to aerobically metabolize citrate, which is extremely rare in E. coli. As the inability to grow aerobically is normally used as a diagnostic criterion with which to differentiate E. coli from other, closely related bacteria, such as Salmonella, this innovation may mark a speciation event observed in the laboratory. E. coli is the type species of the genus (Escherichia) and in turn Escherichia is the type genus of the family Enterobacteriaceae, where the family name does not stem from the genus Enterobacter + "i" (sic.) + "aceae", but from "enterobacterium" + "aceae" (enterobacterium being not a genus, but an alternative trivial name to enteric bacterium).[31][32][33] The original strain described by Escherich is believed to be lost, consequently a new type strain (neotype) was chosen as a representative: the neotype strain is U5/41T,[34] also known under the deposit names DSM 30083,[35] ATCC 11775,[36] and NCTC 9001,[37] which is pathogenic to chickens and has an O1:K1:H7 serotype.[38] However, in most studies, either O157:H7, K-12 MG1655, or K-12 W3110 were used as a representative E. coli. The genome of the type strain has only lately been sequenced.[34] A large number of strains belonging to this species have been isolated and characterised. In addition to serotype (vide supra), they can be classified according to their phylogeny, i.e. the inferred evolutionary history, as shown below where the species is divided into six groups.[22][39] Particularly the use of whole genome sequences yields highly supported phylogenies. Based on such data, five subspecies of E. coli were distinguished.[34] The link between phylogenetic distance ("relatedness") and pathology is small,[34] e.g. the O157:H7 serotype strains, which form a clade ("an exclusive group")—group E below—are all enterohaemorragic strains (EHEC), but not all EHEC strains are closely related. In fact, four different species of Shigella are nested among E. coli strains (vide supra), while E. albertii and E. fergusonii are outside of this group. Indeed, all Shigella species were placed within a single subspecies of E. coli in a phylogenomic study that included the type strain,[34] and for this reason an according reclassification is difficult. All commonly used research strains of E. coli belong to group A and are derived mainly from Clifton's K-12 strain (λ⁺ F⁺; O16) and to a lesser degree from d'Herelle's Bacillus coli strain (B strain)(O7). Salmonella enterica E. albertii E. fergusonii E. coli SE15 (O150:H5. Commensal) E. coli E2348/69 (O127:H6. Enteropathogenic) E. coli ED1a O81 (Commensal) E. coliCFT083 (O6:K2:H1. UPEC) E. coli APEC O1 (O1:K12:H7. APEC E. coli UTI89 O18:K1:H7. UPEC) E. coli S88 (O45:K1. Extracellular pathogenic) E. coli F11 E. coli 536 E. coli UMN026 (O17:K52:H18. Extracellular pathogenic) E. coli (O19:H34. Extracellular pathogenic) E. coli (O7:K1. Extracellular pathogenic) E. coli EDL933 (O157:H7 EHEC) E. coli Sakai (O157:H7 EHEC) E. coli EC4115 (O157:H7 EHEC) E. coli TW14359 (O157:H7 EHEC) Shigella dysenteriae Shigella sonnei Shigella boydii Shigella flexneri E. coli E24377A (O139:H28. Enterotoxigenic) E. coli E110019 E. coli 11368 (O26:H11. EHEC) E. coli 11128 (O111:H-. EHEC) E. coli IAI1 O8 (Commensal) E. coli 53638 (EIEC) E. coli SE11 (O152:H28. Commensal) E. coli B7A E. coli 12009 (O103:H2. EHEC) E. coli GOS1 (O104:H4 EAHEC) German 2011 outbreak E. coli E22 E. coli Olso O103 E. coli 55989 (O128:H2. Enteroaggressive) E. coli HS (O9:H4. Commensal) E. coli ATCC8739 (O146. Crook's E.coli used in phage work in the 1950s) E. coli K-12 W3110 (O16. λ⁻ F⁻ "wild type" molecular biology strain) E. coli K-12 DH10b (O16. high electrocompetency molecular biology strain) E. coli K-12 DH1 (O16. high chemical competency molecular biology strain) E. coli K-12 MG1655 (O16. λ⁻ F⁻ "wild type" molecular biology strain) E. coli BW2952 (O16. competent molecular biology strain) E. coli 101-1 (O? H?. EAEC) E. coli B REL606 (O7. high competency molecular biology strain) E. coli BL21-DE3 (O7. expression molecular biology strain with T7 polymerase for pET system) The first complete DNA sequence of an E. coli genome (laboratory strain K-12 derivative MG1655) was published in 1997. It was found to be a circular DNA molecule 4.6 million base pairs in length, containing 4288 annotated protein-coding genes (organized into 2584 operons), seven ribosomal RNA (rRNA) operons, and 86 transfer RNA (tRNA) genes. Despite having been the subject of intensive genetic analysis for about 40 years, a large number of these genes were previously unknown. The coding density was found to be very high, with a mean distance between genes of only 118 base pairs. The genome was observed to contain a significant number of transposable genetic elements, repeat elements, cryptic prophages, and bacteriophage remnants.[40] Today, several hundred complete genomic sequences of Escherichia and Shigella species are available. The genome sequence of the type strain of E. coli has been added to this collection not before 2014.[34] Comparison of these sequences shows a remarkable amount of diversity; only about 20% of each genome represents sequences present in every one of the isolates, while around 80% of each genome can vary among isolates.[22] Each individual genome contains between 4,000 and 5,500 genes, but the total number of different genes among all of the sequenced E. coli strains (the pangenome) exceeds 16,000. This very large variety of component genes has been interpreted to mean that two-thirds of the E. coli pangenome originated in other species and arrived through the process of horizontal gene transfer.[41] Genes in E. coli are usually named by 4-letter acronyms that derive from their function (when known). For instance, recA is named after its role in homologous recombination plus the letter A. Functionally related genes are named recB, recC, recD etc. The proteins are named by uppercase acronyms, e.g. RecA, RecB, etc. When the genome of E. coli was sequenced, all genes were numbered (more or less) in their order on the genome and abbreviated by b numbers, such as b2819 (=recD) etc. The "b" names were created after Fred Blattner who led the genome sequence effort.[42] Another numbering system was introduced with the sequence of another E. coli strain, W3110, which was sequenced in Japan and hence uses numbers starting by JW... (Japanese W3110), e.g. JW2787 (= recD).[43] Hence, recD = b2819 = JW2787. Note, however, that most databases have their own numbering system, e.g. the EcoGene database[44] uses EG10826 for recD. Finally, ECK numbers are specifically used for alleles in the MG1655 strain of E. coli K-12.[44] Complete lists of genes and their synonyms can be obtained from databases such as EcoGene or Uniprot. Several studies have investigated the proteome of E. coli. By 2006, 1,627 (38%) of the 4,237 open reading frames (ORFs) had been identified experimentally.[45] The interactome of E. coli has been studied by affinity purification and mass spectrometry (AP/MS) and by analyzing the binary interactions among its proteins. Protein complexes. A 2006 study purified 4,339 proteins from cultures of strain K-12 and found interacting partners for 2,667 proteins, many of which had unknown functions at the time.[46] A 2009 study found 5,993 interactions between proteins of the same E. coli strain, though these data showed little overlap with those of the 2006 publication.[47] Binary interactions. Rajagopala et al. (2014) have carried out systematic yeast two-hybrid screens with most E. coli proteins, and found a total of 2,234 protein-protein interactions.[48] This study also integrated genetic interactions and protein structures and mapped 458 interactions within 227 protein complexes. E. coli belongs to a group of bacteria informally known as "coliforms" that are found in the gastrointestinal tract of warm-blooded animals.[31] E. coli normally colonizes an infant's gastrointestinal tract within 40 hours of birth, arriving with food or water or from the individuals handling the child. In the bowel, E. coli adheres to the mucus of the large intestine. It is the primary facultative anaerobe of the human gastrointestinal tract.[49] (Facultative anaerobes are organisms that can grow in either the presence or absence of oxygen.) As long as these bacteria do not acquire genetic elements encoding for virulence factors, they remain benign commensals.[50] E.coli also feacal contaminants. [clarification needed] Nonpathogenic E. coli strain Nissle 1917, also known as Mutaflor, and E. coli O83:K24:H31 (known as Colinfant[51]) are used as probiotic agents in medicine, mainly for the treatment of various gastroenterological diseases,[52] including inflammatory bowel disease.[53] Most E. coli strains do not cause disease,[54] but virulent strains can cause gastroenteritis, urinary tract infections, and neonatal meningitis. It can also be characterized by severe abdominal cramps, diarrhea that typically turns bloody within 24 hours, and sometimes fever. In rarer cases, virulent strains are also responsible for bowel necrosis (tissue death) and perforation without progressing to hemolytic-uremic syndrome, peritonitis, mastitis, septicemia, and Gram-negative pneumonia.[49] There is one strain, E.coli #0157:H7, that produces a toxin called the Shiga toxin (classified as a bioterrorist agent). This toxin causes premature destruction of the red blood cells which then clog the body’s filtering system, the kidneys, causing hemolytic-uremic syndrome (HUS). This in turn causes strokes due to small clots of blood which lodge in capillaries in the brain. This causes the body parts controlled by this region of the brain to not work properly. In addition, this strain causes the buildup of fluid (since the kidneys do not work) leading to edema around the lungs and legs and arms. This increase in fluid buildup especially around the lungs impedes the functioning of the heart, causing an increase in blood pressure.[55][56][57][58] Uropathogenic E. coli (UPEC) is one of the main causes of urinary tract infections.[59] It is part of the normal flora in the gut and can be introduced in many ways. In particular for females, the direction of wiping after defecation (wiping back to front) can lead to fecal contamination of the urogenital orifices. Anal intercourse can also introduce this bacterium into the male urethra, and in switching from anal to vaginal intercourse, the male can also introduce UPEC to the female urogenital system.[59] For more information, see the databases at the end of the article or UPEC pathogenicity. In May 2011, one E. coli strain, O104:H4, was the subject of a bacterial outbreak that began in Germany. Certain strains of E. coli are a major cause of foodborne illness. The outbreak started when several people in Germany were infected with enterohemorrhagic E. coli (EHEC) bacteria, leading to hemolytic-uremic syndrome (HUS), a medical emergency that requires urgent treatment. The outbreak did not only concern Germany, but also 11 other countries, including regions in North America.[60] On 30 June 2011, the German Bundesinstitut für Risikobewertung (BfR) (Federal Institute for Risk Assessment, a federal institute within the German Federal Ministry of Food, Agriculture and Consumer Protection) announced that seeds of fenugreek from Egypt were likely the cause of the EHEC outbreak.[61] The mainstay of treatment is the assessment of dehydration and replacement of fluid and electrolytes. Administration of antibiotics has been shown to shorten the course of illness and duration of excretion of ETEC in adults in endemic areas and in traveller’s diarrhoea. The antibiotic used depends upon susceptibility patterns in the particular geographical region. Currently, the antibiotics of choice are fluoroquinolones or azithromycin, with an emerging role for rifaximin. Oral rifaximin, a semisynthetic rifamycin derivative, is an effective and well-tolerated antibacterial for the management of adults with non-invasive traveller’s diarrhoea. Rifaximin was significantly more effective than placebo and no less effective than ciprofloxacin in reducing the duration of diarrhoea. While rifaximin is effective in patients with E. coli-predominant traveller’s diarrhoea, it appears ineffective in patients infected with inflammatory or invasive enteropathogens.[62] Antibodies against the LT and major CFs of ETEC provide protection against LT-producing ETEC expressing homologous CFs. Oral inactivated vaccines consisting of toxin antigen and whole cells, i.e. the licensed recombinant cholera B subunit (rCTB)-WC cholera vaccine Dukoral and candidate ETEC vaccines have been developed. In different trials, the rCTB-WC cholera vaccine provided high (85–100%) short-term protection. An oral ETEC vaccine consisting of rCTB and formalininactivated E. coli bacteria expressing major CFs has been shown to be safe, immunogenic and effective against severe diarrhoea in American travellers but not against ETEC diarrhoea in young children in Egypt. A modified ETEC vaccine consisting of recombinant E. coli strains overexpressing the major CFs and a more LT-like hybrid toxoid called LCTBA, have been developed and are being tested.[63] [64] Because of its long history of laboratory culture and ease of manipulation, E. coli plays an important role in modern biological engineering and industrial microbiology.[65] The work of Stanley Norman Cohen and Herbert Boyer in E. coli, using plasmids and restriction enzymes to create recombinant DNA, became a foundation of biotechnology.[66] E. coli is a very versatile host for the production of heterologous proteins,[67] and various protein expression systems have been developed which allow the production of recombinant proteins in E. coli. Researchers can introduce genes into the microbes using plasmids which permit high level expression of protein, and such protein may be mass-produced in industrial fermentation processes. One of the first useful applications of recombinant DNA technology was the manipulation of E. coli to produce human insulin.[68] Many proteins previously thought difficult or impossible to be expressed in E. coli in folded form have been successfully expressed in E. coli. For example, proteins with multiple disulphide bonds may be produced in the periplasmic space or in the cytoplasm of mutants rendered sufficiently oxidizing to allow disulphide-bonds to form,[69] while proteins requiring post-translational modification such as glycosylation for stability or function have been expressed using the N-linked glycosylation system of Campylobacter jejuni engineered into E. coli.[70][71][72] Modified E. coli cells have been used in vaccine development, bioremediation, production of biofuels,[73] lighting, and production of immobilised enzymes.[67][74] E. coli is frequently used as a model organism in microbiology studies. Cultivated strains (e.g. E. coli K12) are well-adapted to the laboratory environment, and, unlike wild-type strains, have lost their ability to thrive in the intestine. Many laboratory strains lose their ability to form biofilms.[75][76] These features protect wild-type strains from antibodies and other chemical attacks, but require a large expenditure of energy and material resources. In 1946, Joshua Lederberg and Edward Tatum first described the phenomenon known as bacterial conjugation using E. coli as a model bacterium,[77] and it remains the primary model to study conjugation.[78] E. coli was an integral part of the first experiments to understand phage genetics,[79] and early researchers, such as Seymour Benzer, used E. coli and phage T4 to understand the topography of gene structure.[80] Prior to Benzer's research, it was not known whether the gene was a linear structure, or if it had a branching pattern.[81] E. coli was one of the first organisms to have its genome sequenced; the complete genome of E. coli K12 was published by Science in 1997.[40] By evaluating the possible combination of nanotechnologies with landscape ecology, complex habitat landscapes can be generated with details at the nanoscale.[82] On such synthetic ecosystems, evolutionary experiments with E. coli have been performed to study the spatial biophysics of adaptation in an island biogeography on-chip. Studies are also being performed attempting to program E. coli to solve complicated mathematics problems, such as the Hamiltonian path problem.[83] In 1885, the German-Austrian pediatrician Theodor Escherich discovered this organism in the feces of healthy individuals and called it Bacterium coli commune because it is found in the colon and early classifications of prokaryotes placed these in a handful of genera based on their shape and motility (at that time Ernst Haeckel's classification of bacteria in the kingdom Monera was in place.[84][64][85] Bacterium coli was the type species of the now invalid genus Bacterium when it was revealed that the former type species ("Bacterium triloculare") was missing.[86] Following a revision of Bacterium, it was reclassified as Bacillus coli by Migula in 1895[87] and later reclassified in the newly created genus Escherichia, named after its original discoverer.[88]
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Escherichia coli (E. coli, 大腸菌)는 독일의 소아과의사 Theodor Escherich가 1885년에 발견하였으며, 감마프로테오박테리아 계통군에 속하는 장내세균이다. E. coli는 대장균으로 알려져 있으며, 그람음성, 통성혐기성, 간균형태의 세균으로서 일반적으로 온혈동물의 하부장내(대장과 소장)에서 발견된다. 대부분의 E. coli 균주는 무해하나, 일부 항원형 O157:H7 등은 숙주에서 심각한 식중독을 일으키며 대규모 식품 리콜의 원인이 되기도 한다. 장내의 무해한 정상적인 미생물상으로서 비타민 K2를 생성하고 공생관계를 유지하면서 병원성세균의 장내서식을 방지함으로서 숙주에게 도움을 주기도 한다. 대장균은 대변으로 환경에 배출되게 되며 3일 동안은 호기조건 하에서 대량으로 증식하지만 이후에는 그 수가 천천히 감소한다. 대장균과 다른 통성혐기세균은 장내 균총의 약 0.1%를 차지하고 있으며, 구강을 통한 전염이 질병발생의 주요 경로가 된다. 대장균은 일정 시간 동안만 생체 밖에서 생존할 수 있기 때문에 분변오염에 대한 환경시료를 시험하는 지표생물로 이용되고 있으며, 한편으로는 숙주 외부에서 장기간 생존할 수 있는 대장균에 대한 연구가 진행되고 있다. 실험실에서 쉽고 저렴하게 배양할 수 있으며, 지난 60 년이 넘는 기간 동안 집중적으로 연구되어 온 미생물로서 탄소원과 에너지원이 필수적으로 요구되는 화학합성유기영양생물이다. E. coli는 가장 광범위하게 연구된 원핵생물의 모델미생물이며 재조합 DNA 실험에서 숙주로 사용되는 등 생명공학 및 미생물학 분야에서 매우 중요한 미생물로서 적정조건 하에서 복제시간이 20분 정도로 빠르게 성장한다. 그람음성, 통성혐기성 (산소가 존재할 경우 호기적 호흡으로 ATP를 만들고 산소가 없을 경우는 발효 또는 혐기적 호흡으로 전환) 및 비포자형성 세균으로서 세포는 대개 막대모양이며 길이가 약 2.0 μm 이고 직경이 0.25-1.0 μm 이며 세포 부피는 0.6-0.7 μm3 이다. 세포벽은 얇은 펩티도글리칸층과 외막으로 이루어져 있고, 그람염색에서 대응염색시약 사프라닌에 염색되어 분홍색을 띠게 된다. 세포벽을 둘러싸고 있는 외막은 특정 항생제에 내성을 띠게 하며 대장균은 페니실린에 내성을 갖고 있다. 편모를 통한 운동성이 있으며, 주변편모 배열형태를 가지고 있고, intimin으로 알려진 접착분자는 장의 미세융모에 달라 붙는 작용을 한다. 다양한 기질에서 자랄 수 있으며 혐기적 조건에서 혼합산 발효를 통해 젖산, 숙신산, 에탄올, 아세트산 및 이산화탄소를 생성한다. 혼합산 발효를 통해서는 여러 경로에서 수소 가스를 생성하기 때문에 메탄생성세균 및 유황환원세균과 같은 수소를 소비하는 미생물과 함께 존재하기도 한다. 37°C에서 최적으로 생육하고, 일부 균주는 최대 49°C의 온도에서도 증식 하며, LB배지 또는 글루코스, 일인산암모늄, 염화나트륨, 황산마그네슘, 이인산칼륨을 함유하는 다양한 배지에서 자란다. 호기적 또는 혐기적 호흡에 의해 성장이 촉진되므로 피루브산, 포름산, 수소 및 아미노산과 같은 산화제와 산소, 질산, 푸마르산, 디메틸 술폭사이드 및 트리메틸아민 N-옥사이드와 같은 환원제 등의 다양한 산화환원쌍 시약을 사용한다. 통성혐기성균으로서 산소를 이용하지만, 산소가 없을 때에는 발효 또는 혐기적 호흡을 통해 성장하여 물이 많은 환경에서 생존할 수 있는 수단으로 사용한다. 대장균 및 관련 박테리아는 접합 또는 형질도입을 통해 유전물질이 수평적으로 이동하는 DNA 전달능력을 갖고 있으며, 박테리오파아지로 불리는 박테리아 바이러스를 사용하는 형질도입 과정의 경우, Shigella 세균에 있는 shiga 독소 유전자를 대장균으로 도입시켜 shiga 독소를 생산하는 대장균 E. coli O157:H7의 예가 있다. E. coli는 유전적인 다양성과 표현형적인 다양성이 큰 거대한 세균 집단으로서 유전체염기서열분석을 통해 대장균 및 관련 세균분리균들에 대한 분류학적 재분류가 요구되고 있으나 의학적인 중요성 때문에 이루어지지 않고 있음으로서 가장 다양한 세균 종으로 남아 있으며, 전형적인 대장균 게놈 중 20% 의 유전자가 모든 균주들 사이에서 공유되고 있다. 진화론적인 관점에서 볼 때, Shigella 속 균주 (S. dysenteriae, S. flexneri, S. boydii 및 S. sonnei)는 대장균으로 분류되어야 하며, 대장균의 다른 균주 (예: 재조합 DNA 작업에 일반적으로 사용되는 K-12 균주) 또한 재분류가 가능할 만큼 서로 다른 점이 많다. 균주는 다른 균주와 구별되는 고유한 특성을 지닌 종 내의 하위 집단으로서 그 차이점을 유전자수준에서만 발견 할 수 있으나 생리적특성 또는 생애주기가 바뀌기도 한다. 예를 들어, 균주간에는 병원성, 탄소원이용 능력, 특정 생태학적 틈새를 이용할 수 있는 능력 또는 항생제 저항력이 달라지기도 한다. E. coli는 숙주특이적이기 때문에 환경시료에서 배설물오염원을 밝히는데 사용되며, 어떤 대장균이 물 시료에 존재할 경우, 그 오염이 인간, 다른 포유동물 또는 조류에서 유래했는지의 여부를 분석을 통해 알 수 있다.
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