History of Microbiology

1 What Is a Microbe? n 6 major groups studied by microbiologists ¨ Prokaryotes

n Bacteria n Archaea

¨ Eukaryotes n n n Algae Protists Fungi

¨ Viruses

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 2 Microbes Shape Human History

n Microbes affect food availability ¨ Destroy crops, but preserve food n Bread, wine, cheese

n Chocolate!

n Microbial diseases change history ¨ Black plague in Europe ¨ Smallpox in Americas

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 3 Discovery of Microbes n Light microscope invented in 1600s ¨ Quality improved continuously n Mid-1600s: Robert Hooke observes small eukaryotes n 1676: van Leeuwenhoek discovers bacteria

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 4

Antonie van Leeuwenhoek – Microscopes

Lazzaro Spallanzani – Tried to disprove the Theory of Sponanteous Generation

Louis Pasteur – discovered anaerobes, disproved spontaneous generation, fermentation done by microbes

Microbes Are Living Organisms n Microbes arise only from other microbes ¨ No spontaneous generation ¨ 1688: Redi shows that flies do not spontaneously generate ¨ 1861: Pasteur shows that microbes do not grow in liquid until introduced from outside

Flask neck broken, bacteria fall into and grow in medium No growth Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 13 Joseph Lister – Sterile surgery techniques, inspired by Louis Pasteur’s work on diseases in wine

Germ Theory of Disease n Observations: ¨ Germs can infect and grow on food. n Hypothesis: ¨ Can germs infect and grow on people? ¨ That is, do germs cause disease? n Hypothesis is testable: ¨ Are germs found in infected tissue? ¨ Can transmission of germs cause disease?

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 16 Germ Theory of Disease n Pasteur’s Theory: ¨ Transmission of germs causes disease n All Scientific Theories: ¨ Explain many known observations n For example, transmission of rabies ¨ Provide framework for understanding n Where do diseases come from? ¨ Can be tested further n Do germs cause anthrax? ¨ A scientific theory is NOT a “guess”

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 17 Robert Koch – His postulates helped elucidate the microbial cause of many infectious diseases Koch’s Postulates n Provides means of testing hypothesis: ¨ “Does this germ cause that disease?” n Organism must meet 4 criteria: 1. Microbe always present in diseased

n Absent in healthy 2. Microbe grown in pure culture

n No other microbes present 3. Introduce pure microbe into healthy individual

n Individual becomes sick 4. Same microbe re-isolated from now-sick individual Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 19

Corollary to Germ Theory n Stop germ transmission, stop disease spread ¨ Kill germ, prevent disease n Antiseptics

¨ 1865: Antiseptic surgery §. Joseph Lister

n Antibiotics

¨ 1929–1941: Penicillin §. Alexander Fleming ¨ Many newer antibiotics ¨ Bacteria become resistant

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 21 Corollary to Germ Theory n Stop germ transmission, stop disease spread ¨ Stop spread of germs n Epidemiology, public health measures

¨ Resistant individuals prevent spread of germs

n 1798: Vaccination with cowpox prevents smallpox ¨ Turkish physicians, Lady Montagu, Edward Jenner

Microbiology: An Evolving Science © 2009 W. W. Norton & Company, Inc. 22 Louis Pasteur – developed a method to attenuate microorganisms to make vaccines Paul Ehrlich – discovered the first antibiotic compounds, used to treat syphilis Alexander Fleming – Isolated penicillin, the first antibiotic produced by another organism (mold)