E coli


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A basic outlook upon the E.coli bacteria.

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E coli

  1. 1. Escherichia coli10/6/2012 @ Tenzin Dolma 1
  2. 2. General Facts about E.coli E. coli was discovered by Dr. Theodor Escherich1885 They are gram negative It belongs to the Family Enterobacteriaceae. From Greek word enterikos (intestines) These organisms happily inhabit the intestinaltract of most warm blooded animals.What Good Are E. coli? Aids in digestion Produces our main source of vitamins B12 and K Lives symbiotically with usBad E. coli.. While most E. coli are good for you, there are a few strains of E. coli that are harmful. ~ 5 billion bacteria are there in your intestine alone, most notorious strains of E coliproduces toxin and causes diarrhea, urinary tract infections and other intestinalcomplications.10/6/2012 @ Tenzin Dolma 2
  3. 3. Why are we used as a model organism? Relative simplicity of genome Ease of culturing Rapid growth rate10/6/2012 @ Tenzin Dolma 3
  4. 4. E.Coli Genome The E. coli genome has only 4.6 million bp and about 4300 genes. Humans have thousand times larger approximately 3 billion bp and 20,000 to 25,000 genes. E.coli genome was completely sequenced in 1997 thus making it advantageous for analysis.10/6/2012 @ Tenzin Dolma 4
  5. 5. E.coli growth culture They can grow in even simple nutrient media containing only salts, a source of nitrogen and source of carbon and energy. Division time (40 minutes) normal 20 minutes. From the bacterial colony the mutants can be selected and analyzed easily. Biosynthetic reaction in simple media aids in study of biochemical path ways. E.coli in McConkey media gives pink color since it digests lactose.10/6/2012 @ Tenzin Dolma 5
  6. 6. E.coli growth rate They have a rapid growth rate , under optimal culture condition they divide every 20 minutes. An overnight culture can yield as many as 108 cells. The rapid growth rate has helped in completing the experiments within a shorter time span.10/6/2012 @ Tenzin Dolma 6
  7. 7. Modes of reproduction Binary Fission10/6/2012 @ Tenzin Dolma 7
  8. 8. Conjugation In E.coli This is one mean of genetic recombination in bacteria The picture is an electron micrograph of conjugation between F+ E coli cell and F- E coli cell. The sex pili linking them is clearly visible. F+ : Donor F- : Recipient10/6/2012 @ Tenzin Dolma 8