I finally got around to purchasing and reading a copy of Carl Zimmer’s Microcosm: E.coli and the New Science of Life, and I have to chastise myself for not reading it sooner.
In Microcosm, Zimmer has eloquently condensed a century of scientific study surrounding Eschericia coli into an accurate and flowing story readable by anyone with even just a modest understanding of biology.
As Zimmer points out, E. coli has held a central role in microbiology since its first description by German pediatrician Theodor Escherich in the 19th century. This simple bacterium and its various strains have always been there since we first started looking for the microbes involved in human disease. E.coli‘s normal and pathological roles in the animal body have taught us volumes about the inventive potential of life.
The theme running throughout is that E.coli is a microcosm for understanding all of life. Zimmer reinforces this theme with repeated mention of a Jacques Monod quote, “What is true for E.coli is true for the elephant. Most pointedly, E.coli populations offer clues into the nature of cooperation and competition, altruism and spite.
And of course no book on E.coli would be complete without re-tracing its role in molecular biology. A long series of discoveries, made with E.coli as the experimental system, have elucidated the mechanisms of DNA replication and transcription, regulation of gene expression, and basic metabolism.
Even genetic engineering techniques were pioneered in E.coli, which Zimmer describes in the chapter on “Playing Nature” – a nice twist on the old saying “Playing God,” that is actually more appropriate.
Then there’s the story of E.coli‘s vast evolutionary potential – from antibiotic resistence to immune evasion tactics, the simple and rapid replication cycle of bacteria have enabled natural selection, ecological niches, and population divergence to be studied over the course of tens of thousands of generations.
In the process of his story, Zimmer explains how the bacterial genome is more of a palimpsest rather than an instruction manual – a book that’s been written and re-written many, many times. It’s that palimpsest that serves as both a history book of how it has been modified from its ancestors, but also as an example of “Open Source” text available to modification by its descendents and accessible to horizontal gene transfer.
Lastly and in addition to references to Monod’s quote, the role of one oft-mentioned scientist is a microcosm of E.coli‘s progress in biology – Joshua Lederberg. Zimmer writes of Lederberg in 1957 (p.193):
He was only thirty-two at the time, but he had more than a decade of research behind him, for which he would win a Nobel Prize the following year. He had done most of that work on E.coli. He had discovered that the microbe had sex, and he had used its sex life to draw some of the first maps of its genes. He and his wife had confirmed that genes mutate spontaneously, helping to bring Darwin into the molecular age. They had discovered viruses that could merge into their E.coli hosts. Thanks in large part ot Lederberg, E.coli was becoming the standard tool for studying the molecular basis of life, and other scientists were beginning to use it to translate the genetic code.