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I am investigating the early uses of E. coli as a model organism. Sadly, many early 20th century papers are not in English. In those that are, I have been unable to find explicit statements as to why a researcher chose to use E. coli as a model organism.

Does anyone know of early literature in which this reasoning is stated? I imagine that prior to the widespread use of E. coli, scientists would have had to argue why they chose to use it to investigate biological phenomena not limited to this bacterium alone.

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  • $\begingroup$ Nobody justified the organism then, nor did they need to. If they had discovered something that was new then it was publishable. This "model organism" thing is a recent phenomenon driven by medical research funding and political pressure. What is valid in relation to your question is when E. coli started to be used and why. If you can cite any papers you have found do so, irrespective of language. It's only sad for you. Many of us here in Europe speak or read German and French (the most likely languages in this respect) and other European languages. $\endgroup$ – David Jan 7 '18 at 22:51
  • $\begingroup$ @user297623, while my answer is given below, I'd be curious to read some of the early 20th century French articles - to which you likely refer, but couldn't get a copy of their text, or find an online copy. If there were online copies: could you add a link? $\endgroup$ – tsttst Jan 8 '18 at 4:39
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Historical Fallacies implicit in the Question

  1. “…why a researcher chose to use E. coli as a model organism.”

Researchers did not work with E. coli because they regarded it as a “model organism”. They worked with it because they were bacteriologists and it was a convenient bacterium to use. As Joshua Lederberg wrote in Microbiology Today (2004):

From the beginning, although pathogenic strains were also found, E. coli was used as a representative, harmless bacterium that could be safely and easily cultivated even on synthetic media. On rich media, it will grow with a doubling time of 20 minutes; hence readily visible colonies can be seen overnight when it is plated on agar. Specialized media, like MacConkey’s agar,were developed for the selective isolation and identification of E. coli, as this was used as a global indicator for the pollution of water supplies. Hence, during the first half of the twentieth century E. coli was well known to bacteriologists. However, it was rarely, if ever, mentioned in general biology texts, as bacteria were generally regarded as pre-cellular in complexity and devoid of the nuclei and other genetic apparatus of ‘real’ organisms.

Indeed the term ‘model organism’ was not used in this sense until about 1970, as this Google ngram shows.

  1. “I imagine that prior to the widespread use of E. coli, scientists would have had to argue why they chose to use it to investigate biological phenomena not limited to this bacterium alone.”

You imagine wrongly. They were not sitting down and saying “we want to study this biological phenomenon, what bacteria shall we choose?” and certainly not having to justify themselves on publication. In general they published in specialized bacteriological journals where audience and referees would know why they were using E. coli or whatever. Even when Tatum and Lederberg (see below) published a letter on bacterial recombination in the general science journal, Nature, in 1946 they did not waste space on species justification:

Lederberg and Tatum

No. You are imposing modern attitudes — governed by the contemporary state of science and its funding — upon the science of a completely different era. That is not the way to approach history.

Why did E. coli become the most studied bacterium?

It would seem that the discovery of bacterial recombination in E. coli by Lederberg and Tatum (for which they shared the 1958 Nobel Prize for Physiology or Medicine with George Beadle) was one of the key factors leading to the expansion in the use of E. coli (see Microbiology Today article previously cited). This phenomenon was originally suggested by studies on the transformation pneumococcal bacteria, but its demonstration in the bacterial workhorse, E. coli, opened the doors to the use of a wide range of genetic techniques that could be used for biochemical, as well as molecular biological, studies.

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Very interesting question.

Did early 20th century researchers state why they used E. coli as a model organism?

In short: No (at least in the 1920ies). For instance: Werkman 1927: Vitamin Effects in the physiology of microorganisms does not provide any justification.

Similarly, a recent review by Blount, 2015, eLife: The unexhausted potential of E. coli states:

E. coli's meteoric rise and exalted status in biology stem from how easy it is to find and work with. Hardy, non-pathogenic, and versatile strains that grow quickly on many different nutrients can be isolated from virtually any human. These traits made E. coli a mainstay in microbiology teaching lab collections. Consequently, when early 20th century microbiologists cast about for a model organism, E. coli was one of the most widely available choices.

However, when E. coli entered research in the 19th century, and thus a few decades earlier, it wasn't introduced as a tool or model or teaching material. When it entered science it immediately did so as part of one very profound and important discovery about human digestion, as reviewed by Shulman et al., 2007, Clinical Infectious Diseases

Escherich described in detail Bacterium coli commune (the common colon bacillus now known as Escherichia coli) and Bacterium lactis aërogenes (now known as Klebsiella pneumoniae). He demonstrated their fermentation characteristics and the nature of the gas produced during fermentation, and he showed that, under anaerobic conditions, growth was totally dependent on carbohydrate fermentation. Breaking with dogma, Escherich concluded that any role of the intestinal flora in nutrition was minor at best.

While only peripheral to your main question: E. coli's second boom during the mid of the 20th century, where it entered the field of genetics (that has been occupied by other organisms before) occurred because of discovery of the ability to exchange DNA between individuals - as reviewed by Telis et al. 2014: A Bibliometrics History of the Journal GENETICS (... which would then promote further discoveries relating to the handling and manipulation of DNA...).

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When I read your question the first thing that came to my mind was that Escherichia coli is one of the most common bacteria in human faeces. Of course, the ease of finding and collecting the bacterium (I'm not claiming that the modern source of E. coli is human faeces, I mean not today!) cannot be the only (or the main) factor.

Therefore, I'd like to give you a list of factors — which probably have led the early 20th century researches to choose E. coli as a model — quoting Geoffrey Cooper's "The Cell: A Molecular Approach" (2000).

He starts talking about molecular biology...

E. coli has been especially useful to molecular biologists because of both its relative simplicity and the ease with which it can be propagated and studied in the laboratory. The genome of E. coli, for example, consists of approximately 4.6 million base pairs and encodes about 4000 different proteins. The small size of the E. coli genome provides obvious advantages for genetic analysis, and the sequence of the entire E. coli genome has been determined.

... which is interesting but, of course, not related to your question.

However, in the following paragraphs, he lists a series of characteristics that are pertinent to this question:

  • Experiments are further facilitated by the rapid growth of E. coli under well-defined laboratory conditions. Depending on the culture conditions, E. coli divide every 20 to 60 minutes.

  • A clonal population of E. coli, in which all cells are derived by division of a single cell of origin, can be readily isolated as a colony grown on semisolid agar-containing medium.

  • Because bacterial colonies containing as many as 108 cells can develop overnight, selecting genetic variants of an E. coli strain—for example, mutants that are resistant to an antibiotic, such as penicillin — is easy and rapid.

  • The nutrient mixtures in which E. coli divide most rapidly include glucose, salts, and various organic compounds, such as amino acids, vitamins, and nucleic acid precursors. However, E. coli can also grow in much simpler media consisting only of salts, a source of nitrogen (such as ammonia), and a source of carbon and energy (such as glucose).

It's also worth mentioning that, despite some pathogenic strains, most of the naturally occurring strains of E. coli are inoffensive.


Source: Cooper, G. (2000). The Cell: A Molecular Approach. Sunderland (MA): Sinauer Associates.

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