E. coli was discovered in 1885 and is a gram-negative bacterium that normally lives in the intestines of warm-blooded animals. While most E. coli strains are harmless and aid in digestion, some can cause food poisoning and other intestinal issues. E. coli is commonly used as a model organism for research due its small genome, ease of culturing, and rapid growth rate of 20 minutes per cell division.

1. Escherichia coli
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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 intestinal
tract 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 us
Bad 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 coli
produces toxin and causes diarrhea, urinary tract infections and other intestinal
complications.
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3. Why are we used as a model organism?
Relative simplicity of genome
Ease of culturing
Rapid growth rate
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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.
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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.
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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.
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7. Modes of reproduction
Binary Fission
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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- : Recipient
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