Free Allies and Enemies: How the World Depends on Bacteria by Anne Maczulak Page A

all-purpose cure. But what is now known as western medicine also advanced. Medical schools grew and students for the first time learned anatomy and physiology. As a result, the medical community
    began learning about the effects of infectious disease on internal organs.
    With each of these historical plagues, survivors learned better precautions for escaping infection. Bubonic plague is not contagious, but streets filled with the dead and dying certainly showed that anyone could fall victim. Plague survivors gingerly removed the bodies and took them to the countryside where funeral pyres awaited. This had been the commonest method of disposal throughout the Middle Ages, but on
    occasion people used more imaginative ways to dispose of corpses.
    From 1344 through 1347, Tartars laid siege repeatedly to the port
    city of Caffa (now Feodosija, Ukraine), home to diverse nationalities
    and political persuasions. The plague had already laid waste to the Tartars’ homeland of eastern Asia, and deaths among them mounted even as they surrounded the city. With a body count mounting, the
    Tartars disposed of their deceased by the simple expediency of cata—
    pulting the cadavers over Caffa’s walls. Caffa’s healthy residents would be infected when they collected the bodies for burial. Thus bacteria and humans forged a complex relationship involving disease, sustenance, evil, and God.
     
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    allies and enemies
    Microbiologists save the day
    In 1822 Louis Pasteur was born into a family that had made its living
    tanning hides for generations. A lackluster student, only chemistry held Pasteur’s interest. By the time he reached college, Pasteur would spend hours studying structures of organic compounds and this pursuit likely awakened a curiosity about biology. Still, Pasteur thought of himself as foremost a chemist.
    After winning election as France’s president in 1848, Napoleon
    Bonaparte III made transportation, architecture, and agriculture the
    country’s priorities. New edicts pressured university scientists to follow commercial pursuits. As a professor at the University of Lille, Pasteur grudgingly tucked away his chemistry equipment and brought a microscope into his lab without a clear plan for using it. He decided to teach students about biology’s relationship to agriculture until the time came when he could return to his chemistry experiments.
    Pasteur’s “temporary” foray into biology initiated the most accomplished career in microbiology’s history. His publication list lengthened, and his reputation grew inside and outside of science. By the 1850s, Pasteur had been recruited by France’s alcohol manufacturers
    to improve their fermentation methods. He began by investigating yeast fermentations, perhaps because brewers had not studied it in detail. Pasteur noticed that a drop of liquid from the fermentation flasks gave a curious result in the microscope. When Pasteur put a glass cover slip on top of the drop, some of the microbes avoided the edges of the slip where the liquid was exposed to the air. Pasteur introduced biology to anaerobic bacteria.
    By describing processes taking place in fermentation, Pasteur
    gave the wine and brewing industries greater control over their manufacturing steps. His reputation soared when he diagnosed a disease that had been decimating France’s silk industry. By the 1860s, Pasteur reached national hero status. (Pasteur had incorrectly identified bacteria as the cause of the silkworm disease. Electron microscopes
    were not yet available to enable him to find the real cause: a virus.
    Pasteur nevertheless made the crucial and previously overlooked
    connection between microbes and infection.)
    The public adored Louis Pasteur. Napoleon III invited the microbiologist to his table to hear the latest theories on microbes, and
    chapter 2 · bacteria in history
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    Pasteur happily obliged. He, in fact, had developed the habit of dismissing anyone who questioned his work. Pasteur also