From Alzheimer’s to Zebrafish: Eclectic Science and Regulatory Stories 152
The terms and acronyms used to describe E. coli are confusing and complicated, and it is
difficult to discern all of the causative features and strains (serotypes) for bacteriologists
who are not current with the massive amount of published literature. The recent outbreak
in Germany is a good example. It was caused by a unique and unusual 0104:H4 strain that
can be distinguished from other 0104:H4 strains because it contains a prophage (a mol-
ecule of DNA in the chromosome of the cell) encoding Shiga toxin 2 and a distinct set of
additional virulence and antibiotic-resistance factors.19
Sources of Infection
E. coli is widely disseminated throughout the food chain. In the 1990s and into the early
21st century, the majority of food-borne E. coli outbreaks were caused by the consumption
of contaminated ground beef. Numerous outbreaks and massive recalls of contaminated
meat products continue to plague the meat industry and the public.
Water intended for recreation and for human consumption can also become contami-
nated by causes as simple as a heavy rainstorm. Other means of transmission include
person-to-person and animal-to-person contact. It is also possible that E. coli can be dis-
seminated through the inhalation of dust particles.20
Bioresearch
In the early 20th century, scientists began to study harmless strains of E. coli to understand
the nature of life.21 Now, more is known about E. coli than about any other organism in
the biosphere, including humans. The genome for E. coli is one of the most extensively
mapped of any organism.22
Generations of researchers have probed the existence of the organism, carefully
studying most of its more than 4,000 genes and discovering more and more about evolu-
tion. Through this work, scientists can see an ancient history we all share—a history that
includes the complex features in cells, the common ancestor of all living things, in a world
before DNA. With the knowledge gained from E. coli, genetic engineers can transform
corn, pigs and even fish.
E. coli has also been used to define the molecular and cellular mechanisms underlying
how microbes cause disease.23 Thousands of experiments have been run to understand the
growth of E. coli, and several Nobel prizes have been awarded because of them.24
There are at least five reasons for using E. coli in gene cloning and other genetic
research. The first is its relatively small genome size, about 4,400 genes. Second is the
rapid growth rate. Genetic experimental results can be determined in hours instead of
days or years. Third, the organism is relatively innocuous, if properly handled. Fourth, the
E. coli genome has been completely sequenced and thus its protein expression mechanisms
are well known. Fifth, and perhaps most important, is that E. coli is readily transformed
with plasmids (DNA that can replicate independent of the main chromosome) and other
vectors and easily undergoes transduction by taking up foreign DNA.25
The collective knowledge derived from all of the research makes it relatively simple
for a scientist to create a mutant E. coli with missing genes and then to learn from its
behavior what that gene is for. Bacterial geneticists now have a good idea of what all but
600 genes represent. From the hundreds or thousands of papers published on E. coli comes
a portrait of a living thing that is governed by rules that often apply to all of life.26
Final Thoughts
Carl Zimmer, an award-winning science writer, perhaps best describes the friend and foe
dichotomy for E. coli:
“E. coli may seem like an odd choice as a guide to life if the only place you’ve heard
about it is in the news reports of food poisoning. There are certainly some deadly
The terms and acronyms used to describe E. coli are confusing and complicated, and it is
difficult to discern all of the causative features and strains (serotypes) for bacteriologists
who are not current with the massive amount of published literature. The recent outbreak
in Germany is a good example. It was caused by a unique and unusual 0104:H4 strain that
can be distinguished from other 0104:H4 strains because it contains a prophage (a mol-
ecule of DNA in the chromosome of the cell) encoding Shiga toxin 2 and a distinct set of
additional virulence and antibiotic-resistance factors.19
Sources of Infection
E. coli is widely disseminated throughout the food chain. In the 1990s and into the early
21st century, the majority of food-borne E. coli outbreaks were caused by the consumption
of contaminated ground beef. Numerous outbreaks and massive recalls of contaminated
meat products continue to plague the meat industry and the public.
Water intended for recreation and for human consumption can also become contami-
nated by causes as simple as a heavy rainstorm. Other means of transmission include
person-to-person and animal-to-person contact. It is also possible that E. coli can be dis-
seminated through the inhalation of dust particles.20
Bioresearch
In the early 20th century, scientists began to study harmless strains of E. coli to understand
the nature of life.21 Now, more is known about E. coli than about any other organism in
the biosphere, including humans. The genome for E. coli is one of the most extensively
mapped of any organism.22
Generations of researchers have probed the existence of the organism, carefully
studying most of its more than 4,000 genes and discovering more and more about evolu-
tion. Through this work, scientists can see an ancient history we all share—a history that
includes the complex features in cells, the common ancestor of all living things, in a world
before DNA. With the knowledge gained from E. coli, genetic engineers can transform
corn, pigs and even fish.
E. coli has also been used to define the molecular and cellular mechanisms underlying
how microbes cause disease.23 Thousands of experiments have been run to understand the
growth of E. coli, and several Nobel prizes have been awarded because of them.24
There are at least five reasons for using E. coli in gene cloning and other genetic
research. The first is its relatively small genome size, about 4,400 genes. Second is the
rapid growth rate. Genetic experimental results can be determined in hours instead of
days or years. Third, the organism is relatively innocuous, if properly handled. Fourth, the
E. coli genome has been completely sequenced and thus its protein expression mechanisms
are well known. Fifth, and perhaps most important, is that E. coli is readily transformed
with plasmids (DNA that can replicate independent of the main chromosome) and other
vectors and easily undergoes transduction by taking up foreign DNA.25
The collective knowledge derived from all of the research makes it relatively simple
for a scientist to create a mutant E. coli with missing genes and then to learn from its
behavior what that gene is for. Bacterial geneticists now have a good idea of what all but
600 genes represent. From the hundreds or thousands of papers published on E. coli comes
a portrait of a living thing that is governed by rules that often apply to all of life.26
Final Thoughts
Carl Zimmer, an award-winning science writer, perhaps best describes the friend and foe
dichotomy for E. coli:
“E. coli may seem like an odd choice as a guide to life if the only place you’ve heard
about it is in the news reports of food poisoning. There are certainly some deadly