E. coli is Critical to Genetic Advances

Reasons This Microorganism is Useful

The microorganism Escherichia coli (E.coli) has a long history in the biotechnology industry and is still the microorganism of choice for most gene cloning experiments.

Although E. coli is known by the general population for the infectious nature of one particular strain (O157:H7), few people are aware of how versatile and widely used it is in research as a common host for recombinant DNA (new genetic combinations from different species or sources).

The following are the most common reasons E. coli is a tool used by geneticists.

Genetic Simplicity

Bacteria make useful tools for genetic research because of their relatively small genome size compared to eukaryotes (has a nucleus and membrane-bound organelles). E. coli cells only have about 4,400 genes whereas the human genome project has determined that humans contain approximately 30,000 genes.

Also, bacteria (including E. coli) live their entire life in a haploid state (having a single set of unpaired chromosomes). As a result, there is no second set of chromosomes to mask the effects of mutations during protein engineering experiments.

Growth Rate

Bacteria typically grow much faster than more complex organisms. E. coli grows rapidly at a rate of one generation per 20 minutes under typical growth conditions.

This allows for the preparation of log-phase (logarithmic phase, or the period in which a population grows exponentially) cultures overnight with mid-way to maximum density. 

Genetic experimental results in mere hours instead of several days, months, or years. Faster growth also means better production rates when cultures are used in scaled-up fermentation processes.

Safety

E. coli is naturally found in the intestinal tracts of humans and animals where it helps provide nutrients (vitamins K and B12) to its host. There are many different strains of E. coli that may produce toxins or cause varying levels of infection if ingested or allowed to invade other parts of the body.

Despite the bad reputation of one particularly toxic strain (O157:H7), E. coli strains are relatively innocuous when handled with reasonable hygiene.

Well Studied

The E. coli genome was the first to be completely sequenced (in 1997). As a result, E. coli is the most highly studied microorganism. Advanced knowledge of its protein expression mechanisms makes it simpler to use for experiments where expression of foreign proteins and selection of recombinants (different combinations of genetic material) is essential.

Foreign DNA Hosting

Most gene cloning techniques were developed using this bacterium and are still more successful or effective in E. coli than in other microorganisms. As a result, the preparation of competent cells (cells that will take up foreign DNA) is not complicated. Transformations with other microorganisms are often less successful.

Ease of Care

Because it grows so well in the human gut, E. coli finds it easy to grow where humans can work. It's most comfortable at body temperature.

While 98.6 degrees may be a bit warm for most people, it's easy to maintain that temperature in the laboratory. E. coli lives in the human gut and is happy to consume any type of predigested food. It can also grow both aerobically and anaerobically.

Thus, it can multiply in the gut of a human being or animal but is equally happy in a petri dish or flask.

How E. Coli Makes a Difference

E. Coli is an incredibly versatile tool for genetic engineers; as a result, it has been instrumental in producing an amazing range of medicines and technologies. It has even, according to Popular Mechanics, become the first prototype for a bio-computer: "In a modified E. coli 'transcriptor,' developed by Stanford University researchers March 2007, a strand of DNA stands in for the wire and enzymes for the electrons. Potentially, this is a step towards building working computers within living cells that could be programmed to control gene expression in an organism."

Such a feat could only be accomplished with the use of an organism that is well understood, easy to work with, and able to replicate quickly.