Week-1 micro.pdf

 1673-1723: Anton van Leeuwenhoek described live microorganisms Figure 1.2a  The Debate over Spontaneous Generation Spontaneous generation: The hypothesis that living organisms arise from nonliving matter; a “vital force” forms life Biogenesis:...

 1673-1723: Anton van Leeuwenhoek described live microorganisms Figure 1.2a  The Debate over Spontaneous Generation Spontaneous generation: The hypothesis that living organisms arise from nonliving matter; a “vital force” forms life Biogenesis: The hypothesis that the living organisms arise from preexisting life Conditions Results Three jars covered with fine No maggots net Three open jars Maggots appeared From where did the maggots come? What was the purpose of the sealed jars? Spontaneous generation or biogenesis? Conditions Results Nutrient broth placed in Microbial growth flask, heated, not sealed Nutrient broth placed in No microbial growth flask, heated, then sealed Spontaneous generation or biogenesis? Figure 1.3  Steam, forced out open end Nonsterile liquid Neck of flask Liquid sterilized poured into flask drawn out in flame by extensive heating © 2012 Pearson Education, Inc.  Dust and microorganisms trapped in bend Open end Long time Liquid cooled Liquid remains slowly sterile indefinitely © 2012 Pearson Education, Inc.  Short time Flask tipped so Liquid putrefies microorganism-laden dust contacts sterile liquid © 2012 Pearson Education, Inc.  Pasteur demonstrated that these spoilage bacteria could be killed by heat that was not hot enough to evaporate the alcohol in wine Pasteurization is the application of a high heat for a short time Figure 1.4  1876: Robert Koch proved that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, to prove that a specific microbe causes a specific disease Figure 1.4  Koch, Infectious Disease, and the Rise of Pure Cultures Robert Koch (1843–1910) Koch’s postulates Developed techniques (solid media) for obtaining pure cultures of microbes, some still in existence today Awarded Nobel Prize for Physiology and Medicine in 1905 © 2012 Pearson Education, Inc.  KOCH’S POSTULATES Diseased Healthy The Postulates: Tools: animal animal 1. The suspected pathogen Microscopy, Red must be present in all staining blood Observe cases of the disease cell blood/tissue Red and absent from healthy under the blood Suspected microscope cell animals. pathogen 2. The suspected pathogen Laboratory Streak agar plate with sample No must be grown in pure culture organisms from either culture. diseased or present Colonies of healthy animal suspected pathogen Inoculate healthy animal with cells of suspected pathogen 3. Cells from a pure Experimental culture of the suspected animals pathogen must cause Diseased animal disease in a healthy animal. Remove blood or tissue sample and observe by microscopy 4. The suspected pathogen Laboratory Suspected Laboratory Pure culture reisolation pathogen culture (must be must be reisolated and same shown to be the same and culture organism as the original. as before) © 2012 Pearson Education, Inc.  1928: Alexander Fleming discovered the first antibiotic Fleming observed that Penicillium fungus made an antibiotic, penicillin, that killed S. aureus 1940s: Penicillin was tested clinically and mass produced Figure 1.5  Immunology is the study of immunity. Vaccines and interferons are being investigated to prevent and cure viral diseases. The use of immunology to identify some bacteria according to serotypes was proposed by Rebecca Lancefield in 1933. Figure 1.4 Figure 28.8c Applications of Microbiology, p. 801