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Dr. Manuel Varela – A Coli Named Escherichia

Apr 3, 2017 by

Image result for Dr. Theodor Escherich photosAn Interview with Dr. Manuel Varela- A Coli Named Escherichia

Michael F. Shaughnessy –

  1. Dr. Varela, I know it may seem strange but there seems to be an E. coli named after a great scientist named Theodor Escherich.   How did this come about?

The Escherichia coli bacterium was named as such to honor its discoverer, Dr. Theodor Escherich. He was the very first investigator to isolate the microbe in a pure state, to grow it, and to study it in detail.

In Escherich’s time, around the 1880s, and for prior generations, infant mortality had been a chronically serious concern, and the death rates due to infant diarrhea had been particularly alarming, especially for Dr. Escherich, a bacteriologist and pediatrician practicing in a medical clinic in Germany.

As a result, Dr. Escherich had become interested in knowing about the kinds of bacteria that reside in the feces of infants. He had previously learned basic bacteriological methods from Wilhelm Frobenius, who in turn had learned of the techniques from the famous Dr. Koch himself.

Thus, knowing how to culture pure versions of bacteria and how to fundamentally characterize his pure bacteria, Dr. Escherich used his newly acquired bacteriological skills to obtain samples of bacteria from the diapers of healthy infants. Amongst the many types of bacteria found in the infant feces, Dr. Escherich had described a brand new bacterium that he called Bacterium coli commune, or B. coli for short. Because the new microbe was a common one, Dr. Escherich tacked onto the name the term commune. This was the microbe for which he would later be honored by his grateful colleagues by naming the bacterium after him. This was a great honor, indeed.

2. Now, where and when was this famous scientist born?

Theodor Escherich was born on November 29, 1857 in Ansbach, a Bavarian state of Germany. He had dual citizenship in both Germany and Austria.

3. What was his childhood and early years like?

Escherich’s father, Ferdinand, was also a pediatrician, as well as a statistician; and Escherich’s mother, Maria Sophie Frederike von Stromer, was the daughter of a prominent Bavarian military officer and third wife of Ferdinand. Theodor’s father had also been quite concerned with the alarming mortality rates observed among infants and with the inadequate quality of healthcare that had been provided to the poor. Apparently, these concerns had been handed down to the younger Escherich and consequently had been an important influence in his later years.

Unfortunately, Escherich’s mother passed away when Theodor was only 5 years old. It had been reported that due to his behavior problems associated with instigating pranks (it is unclear what the nature of these pranks were), the young Escherich was sent away to a Jesuit boarding school to finish his education.

Escherich had subsequently entered the military and served in the Austrian army. After having completed his military term of service Escherich studied medicine, earning his doctorate in 1881, with top grades.

4. For the non-scientists among us, what exactly is coli, and is there a difference between coli and coli?

This is a very good question. When naming new microorganisms, like all other newly discovered living organisms, precise scientific names are assigned to them, for proper classification purposes.  These scientific names will then be used to describe the organism by any scientist anywhere in the world when reporting future studies on them in the journals and in books.

The first term, Escherichia, is known as the genus (plural, genera); the genus is usually a noun (in this case the noun is a person—Dr. Escherich).  By scientific convention, the genus is always capitalized and either underlined or italicized, when reported in the scientific literature.

The second term, coli, is called a specific epithet; it is usually an adjective.  In this case, the term coli refers to the source of the E. coli bacteria, namely, the colon, and because these bacteria are found in the colons of all living animals, the plural of colon (coli) is used. By convention, the specific epithet (coli) is not capitalized but is still underlined or written in italics.

Together, the genus and specific epithet, constitute the species of a given organism, or in our discussion, a microorganism (and in this case the species is Escherichia coli). Sometimes, in the literature, the species name will be spelled out fully during the very first time it is mentioned in an article, then afterwards the genus is simply abbreviated, e.g., E. coli.

5. Why is this particular coli of importance? What impact has this made on science and medicine?

  1. coli happens to be an extremely important organism for several main reasons. First, we know a great deal about this microbe, and this fact, therefore, makes it important as a model for scientific study of basic biology. In fact, I might be so bold as to categorically state that we know more about E. coli than about any other organism in the world. Its entire DNA genome sequence has been determined, and we know every single nucleotide base-pair in its genome. We know every gene, and many of its proteins, the amino acids that make up the proteins, and their biological functions; we know many of its other molecules, like sugars, fats, nucleic acids, ions, etc.

Consequently, we know a tremendous amount of knowledge about its physiology, biochemistry and genetics. We certainly don’t know everything there is to know about E. coli, of course, and we obviously never will know everything about it.  E. coli is, nonetheless, the best understood organism ever known to humankind, period.

Second, as I mentioned earlier, it is permanently present in the gut of all animals and humans. Thus, we need to know what it’s doing there. We know, for instance, that E. coli is making our vitamin K, which is quite helpful to us, of course.

It is also very likely that it is protecting us from pathogenic microbes, keeping them in check by effectively competing for limited resources in the gut.

Third, E. coli is used by scientists who are molecular biologists as the “laboratory rat” for the cloning of virtually every gene that’s studied. Most, if not all, genes, including human genes that are cloned for study, are often put into E. coli during the cloning process, in order to closely examine the genes and the proteins that the DNA genes encode.

For instance, this gene cloning into E. coli allows scientists to study human genetic diseases in which a defective gene is the causative agent of a given genetic disorder. Many human genetic diseases can be studied by evaluating the physiology and biochemistry of defective genes, their protein products, and those of their normal counterparts, within the E. coli bacteria. Thus, E. coli is a common and useful tool for basic scientific and medical research. In summary E. coli serves to advance scientific knowledge and to improve human health.

Fourth, E. coli is similarly used for applied research. For example, when using genetic engineering tools, E. coli is employed to help manufacture useful products, such as fuels, plastics, chemicals, medicines, vitamins, hormones, etc.

Fifth, strangely, the presence of E. coli anywhere outside of a proper scientific laboratory is an indicator of fecal contamination. For example, if E. coli is detected in water or soil, it indicates that these environments have been exposed to human or animal fecal matter. This E. coli fecal contamination presents an important issue pertaining to the maintenance of proper sanitation for water, sewage, and the environment.

Lastly, although the E. coli bacteria that live in the gastrointestinal tract of all living humans and animals are actually completely harmless microbes, there are, nevertheless, a few E. coli variants that are dangerous to humans and other animals. These deviants of the otherwise harmless E. coli are pathogenic in that they cause disease (morbidity) and death (mortality) in both humans and animals. They are often transmitted to their victims by the so-called oral-fecal mode of transmission.

One of these pathogenic E. coli variants, a strain of the bacterium called O157:H7, caused a serious outbreak of foodborne poisoning from beef that had been contaminated with the strain during the so-called “Jack in the Box” incident in which over 700 victims became terribly ill and 4 children died. Many of the survivors had permanent kidney damage.

There are about half a dozen pathogenic E. coli variants. One of these E. coli pathogens mimics the effects of cholera, a disease typically caused by another bacterium called Vibrio cholerae.  Another pathogenic strain of E. coli causes a serious condition reminiscent of that caused by the bacterium called Shigella dysenteriae, often called dysentery or shigellosis. One newer E. coli strain, called NC101, causes colorectal cancer.

Antimicrobial agents, such as antibiotics, are frequently prescribed to patients suffering from the E. coli pathogens in order to treat their diseases that they cause. Unfortunately, many of these pathogenic E. coli strains are becoming increasingly resistant to the medicines used to treat them, making efficacious treatment correspondingly difficult to come about.

6. What other great discoveries are attributed to Theodor Escherich?

Dr. Escherich became a noted expert on his “B. coli” bacterium. His studies demonstrated much of the early knowledge gained about E. coli.  For instance, Dr. Escherich was responsible for finding out about how to grow it in the lab and about its bacteriological structure. He used Gram’s staining technique to show that E. coli is a Gram-negative microbe. Shortly after he discovered the microbe, Dr. Escherich was the first to study its physiology, many aspects of which are still taught in the microbial physiology and microbiology textbooks nowadays.

Dr. Escherich also became an advocate for the improvement and proper healthcare of neonates in order to prevent infant mortality. These issues are still of importance to this day.

7. What have I neglected to ask about this great scientist?

Dr. Escherich’s work started what is considered an impressive series of advancements in the sciences. The magnitude of influence by this tiny microbe in science is tremendous. One interesting consequence is the significant number of Nobel laureates who earned their prizes using Dr. Escherich’s famous E. coli bacterium in their studies. It has been reported that about a dozen Nobel prizes involved the famous E. coli.

For instance, one of my favorites is the discovery of the so-called lac operon, an E. coli genetic locus present on its genome that’s regulated by inducers (lactose that’s converted to allolactose) and a repressor (a DNA binding protein that prevents gene expression).

The lac operon also encodes its regulated structural protein machinery, i.e., a lactose transporter called a permease and an enzyme, called β-galactosidase that starts the breakdown of lactose for energy, to allow E. coli to grow. This biological machinery makes it possible for E. coli to eat the milk sugar lactose. The Nobel for this operon was awarded in 1965 to Drs. Jacques Monod, François Jacob, and André Lwoff, from the Pasteur Institute, in Paris, France, for their discovery of this gene expression regulation system within the chromosome of E. coli.  Clearly, there is still much work to be done with E. coli, and it is Dr. Escherich who started it all.

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