History of Microbiology

HISTORY OF MICROBIOLOGY History of Microbiology Early Studies Before 17th century, study of microbiology was hampered by the lack of appropriate tools to observe microbes. Robert Hooke: In 1665 built a compound light microscope and used it to observe thin slices of cork. Coined the word cell. Anton van Leeuwenhoeck: In 1673 was the first person to observe live microorganisms which he called “animalcules” (bacteria, protozoa), using single-lens microscopes that he designed. History of Microbiology Spontaneous Generation vs Biogenesis Before 1860s many scientists believed in Spontaneous generation, i.e.: That living organisms could arise spontaneously from nonliving matter:     Mice come from rags in a basket. Maggots come from rotting meat. Ants come from honey. Microbes come from spoiled broth. History of Microbiology Spontaneous Generation vs Biogenesis Theory of Biogenesis: Belief that living cells can only arise from other living cells. Francesco Redi: In 1668 proved that maggots do not arise spontaneously from decaying meat. Lazaro Spallanzani: In 1765 found that nutrient broth that had been heated in a sealed flask would not become contaminated with microbes.  Some proponents of spontaneous generation argued that boiling had destroyed the “life force” of air in flask.  Others argued that microbes were different from other life forms. History of Microbiology Spontaneous Generation vs Biogenesis Debate was finally settled by Pasteur. Louis Pasteur: In 1861 finally disproved spontaneous generation when he demonstrated that microorganisms in the environment were responsible for microbial growth in nutrient broth.  Designed swan neck flasks that allowed air in, but trapped microbes in neck.  Developed aseptic technique: Practices that prevent contamination by unwanted microorganisms. History of Microbiology Golden Age: 1857-1914 Rapid advances led to the development of microbiology as a science. Pasteur’s Contributions to Microbiology: Fermentation: Pasteur found that yeasts were responsible for converting sugar into alcohol in the absence of air.  Souring and spoilage were caused by bacterial contamination of beverages. History of Microbiology Golden Age: 1857-1914 Pasteur’s Contributions: Pasteurization: Developed a process in which liquids are heated (at 65oC) to kill most bacteria responsible for spoilage. Disease Causes: Identified three different microbes that caused silkworm diseases. Vaccine: Developed a vaccine for rabies from dried spinal cords of infected rabbits.  Directed Pasteur Institute until his death in 1895. History of Microbiology Golden Age: 1857-1914 Germ Theory of Disease: Belief that microbes cause diseases. Before, most people believed diseases were caused by divine punishment, poisonous vapors, curses, witchcraft, etc. Agostino Bassi (1835): Found that a fungus was responsible for a silkworm disease. Ignaz Semmelweis (1840s): Demonstrated that childbirth fever was transmitted from one patient to another, by physicians who didn’t disinfect their hands. He was ostracized by colleagues. History of Microbiology Golden Age: 1857-1914 Germ Theory of Disease: Joseph Lister (1860): Used disinfectant to treat surgical wounds, greatly reducing infection rates. Considered the father of antiseptic surgery. Robert Koch (1876): First person to conclusively prove that a specific bacterium caused a disease.  Germ Theory: One microbe causes one specific disease.  Proved that Bacillus anthracis causes anthrax in cattle.  Later identified bacterium that causes tuberculosis. History of Microbiology Modern Microbiology: After 1914 Chemotherapy: Treatment of a disease by using a chemical substance. Chemical must be more poisonous to microbe than host. Quinine: First known chemical to treat a disease (malaria). Used by Spanish conquistadors. Synthetic Drugs: Made in the laboratory. Antibiotics: Produced naturally by fungi and bacteria. History of Microbiology Modern Microbiology: After 1914 Paul Ehrlich (1910): Search for “magic bullet”.  Discovered salvarsan, an arsenic derivative, was effective against syphilis. Alexander Fleming (1928): Discovered that penicillin produced by the mold Penicillium notatum was able to prevent microbial growth.  Penicillin was not mass produced until the 1940s. Rene Dubos (1939): Discovered two antibiotics (gramidin and tyrocidine) produced by bacterium (Bacillus brevis). History of Microbiology Modern Microbiology: After 1914 Problems with Chemotherapy: Toxicity Drug resistant microbes Diversity of Microorganisms I. Bacteria (Sing. Bacterium) Small, single-celled (unicellular) organisms. Procaryotes: “Before nucleus”. Lack the following structures:  Nuclear membrane around DNA  Membrane bound organelles      Mitochondria Chloroplasts Golgi apparatus Endoplasmic reticulum Lysosomes