History of Microbiology

• Girolamo Fracastoro (1478- 1553) proposed that disease was caused by invisible living creatures (germs of contagion; seminaria morbis- seeds of disease)


  1546
• Antoni van Leeuwenhoek observed bacteria and protozoa using his homemade microscopes


  1684
• The Golden Age of Microbiology was driven by the search for the following answers

  • Is spontaneous generation of microbial life possible?
  • What causes fermentation?
  • What causes disease?
  • How can we prevent infection and disease?
• Spontaneous Generation Theory


  The theory that living organisms can arise from non-living matter
• Francesco Redi (1626-1697) disproved spontaneous generation through meat.
• John Needham (1745) supported spontaneous generation when he boiled broth.
• Lazzaro Spallanzani (1729–1799) disproved spontaneous generation through boiling gravy.
• Rudolf Virchow (1858) proposed the Theory of Biogenesis - that living cells can only arise from other living cells
• Louis Pasteur (1822-1895) disproved spontaneous generation through the swan neck experiment.
• John Tyndall and Ferdinand Cohn provided further support against spontaneous generation
• Germ Theory of Disease


  The theory that many diseases are caused by the presence and actions of specific microorganisms
• Edward Jenner introduced a vaccination procedure for smallpox


  1798/1796
• Ignaz Semmelweis (1848) proposed that handwashing could prevent the spread of infection
• Joseph Lister (1827-1912) pioneered antiseptic surgery and developed the phenol solution.
• Robert Koch (1843-1910) made many advances in microbiology, especially through the development of Koch's postulate.
• Advances in microbiology by Koch

  • Simple staining techniques for bacterial cells and flagella
  • 1st photomicrograph of bacteria
  • 1st photomicrograph of bacteria in diseased tissue
  • Techniques for estimating the number of bacteria in a solution based on the number of colonies that form after inoculation onto a solid surface
  • The use of steam to sterilize growth media
  • The use of Petri dishes to hold solid growth media
  • The use of agar as a solidfying agent
  • Aseptic laboratory techniques such as transferring bacteria b/w media with heat-sterilized platinum wire
  • Elucidation of bacteria as distinct species
  • Development of nutrient broth and agar
• Richard Petri invented the Petri dish
• Alexander Fleming (1881-1955) discovered penicillin
• Selman Waksman (1888-1973) discovered streptomycin
• Martinus Beijerinck and Sergei Winogradsky were pioneers of microbial ecology
• Carl Woese discovered the Archaea domain of life
• Thomas Brock discovered Thermus aquaticus, a thermophilic bacterium
• Kary Mullis (1944-2019) invented the Polymerase Chain Reaction (PCR)
• CRISPR is a gene editing technology