Microbiology Chapter 1 - Tortora Fall 24 PDF

Chapter 1 The Microbial World and You © 2013 Pearson Education, Inc. Classifying Living Organisms This timeline shows how the shape of the tree of life has...

Chapter 1 The Microbial World and You © 2013 Pearson Education, Inc. Classifying Living Organisms This timeline shows how the shape of the tree of life has changed over the centuries. Even today, the taxonomy of living organisms is continually being reevaluated The Three Domain System Woese and Fox’s phylogenetic tree contains three domains: Bacteria, Archaea, and Eukarya. Domains Archaea and Bacteria contain all prokaryotic organisms, and Eukarya contains all eukaryotic  Naming and Classifying Microorganisms Linnaeus established the system of scientific nomenclature Each organism has two names: the genus and specific epithet  Scientific Names After the first use, scientific names may be abbreviated with the first letter of the _____ and the specific epithet: – Escherichia coli and Staphylococcus aureus are found in the human body – E. coli is found in the large intestine, and S. aureus is on skin Are italicized or underlined – The genus is capitalized; the specific ________ is lowercase  Types of Microorganisms Bacteria Archaea Fungi Protozoa Algae Viruses Multicellular animal parasites Bacteria Prokaryotes Peptidoglycan cell walls Binary fission For energy, use organic chemicals, inorganic chemicals, or photosynthesis  Archaea Prokaryotic Lack peptidoglycan Live in extreme environments Include: – Methanogens – Extreme halophiles – Extreme thermophiles  Fungi Eukaryotes Chitin cell walls Use organic chemicals for energy Molds and mushrooms are multicellular, consisting of masses of mycelia, which are composed of filaments called hyphae Yeasts are unicellular  Protozoa Eukaryotes Absorb or ingest organic chemicals May be motile via pseudopods, cilia, or flagella Protozoan Giardia lamblia, an intestinal protozoan parasite that infects humans and other mammals, causing severe  Algae Eukaryotes Cellulose cell walls Use photosynthesis for energy Produce molecular oxygen and organic compounds Viruses Acellular Consist of DNA or RNA core Core is surrounded by a protein coat Coat may be enclosed in a lipid envelope Are replicated only when they are in a living host cell  Viruses (a)Members of the Coronavirus family can cause respiratory infections like the common cold, severe acute respiratory syndrome (SARS), and Middle East respiratory syndrome (MERS). Here they are viewed under a transmission electron microscope (TEM). (b)Ebolavirus, a member of the Filovirus family, as visualized using a TEM.  Multicellular Animal Parasites Eukaryotes Multicellular animals Parasitic flatworms and roundworms are called helminths Microscopic stages in life cycles  Size Range of Microbes The relative sizes of various microscopic and nonmicroscopic objects. Note that a typical virus measures about 100 nm, 10 times smaller than a typical bacterium (~1 μm), which is at least 10 times smaller than a typical plant or animal cell (~10–100 μm). An object must measure about 100 μm to be visible without a microscope.  The First Observations 1665: Robert Hooke reported that living things are composed of little boxes, or cells Published Micrographia in 1665  The First Observations 1673–1723: Anton van Leeuwenhoek described live microorganisms 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 living organisms arise from preexisting life  Evidence Pro and Con 1668: Francesco Redi filled 6 jars with decaying meat Conditions Results Three jars covered with fine net No maggots Three open jars Maggots appeared From where did the maggots come? What was the purpose of the sealed jars? Spontaneous generation or biogenesis?  Biogenesis Francesco Redi’s experimental setup consisted of an open container, a container sealed with a cork top, and a container covered in mesh that let in air but not flies. Maggots only appeared on the meat in the open container. However, maggots were also found on the gauze of the gauze-covered container.  Evidence Pro and Con 1765: Lazzaro Spallanzani boiled nutrient solutions in flasks – no growth (disproved Needham) Conditions Results Nutrient broth placed in flask, No microbial growth heated, then sealed Spontaneous generation or biogenesis? The Golden Age of Microbiology 1857–1914 Beginning with Pasteur’s work, discoveries included the relationship between microbes and disease, immunity, and antimicrobial drugs Biogenesis - Pasteur’s Experiments (a)French scientist Louis Pasteur, who definitively refuted the long-disputed theory of spontaneous generation. (b)The unique swan-neck feature of the flasks used in Pasteur’s experiment allowed air to enter the flask but prevented the entry of bacterial and fungal spores. (c)Pasteur’s experiment consisted of two parts. In the first part, the broth in the flask was boiled to sterilize it. When this broth was cooled, it remained free of contamination. In the  What Causes Fermentation? Spoiled wine and beer threatened livelihood of vintners and brewers, so they funded research into how to promote production of alcohol, but prevent spoilage by acid during fermentation Some believed air caused fermentation reactions, while others insisted living organisms caused fermentation This debate also linked to debate over spontaneous generation. How Pasteur applied the scientific method in investigating the nature of fermentation.  What Causes Disease? p98 1835: Agostino Bassi showed that a silkworm disease was caused by a fungus 1865: Pasteur believed that another silkworm disease was caused by a protozoan 1840s: Ignaz Semmelweis advocated handwashing to prevent transmission of puerperal fever from one obstetrical patient to another 1860s: Applying Pasteur’s work showing microbes are in the air, can spoil food, and cause animal diseases, Joseph Lister used a chemical disinfectant to prevent surgical wound infections  The Germ Theory of Disease 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 (p 401) Table 1.2  Vaccination p 808 1796: Edward Jenner inoculated a person with ______ virus, who was then protected from smallpox Vaccination is derived from vacca, for ___ The protection is called immunity  The Birth of Modern Chemotherapy Treatment with chemicals is chemotherapy Chemotherapeutic agents used to treat infectious disease can be synthetic drugs or antibiotics Antibiotics are chemicals produced by bacteria and fungi that inhibit or kill other microbes A Fortunate Accident—Antibiotics 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  Modern Developments in Microbiology Bacteriology is the study of bacteria Mycology is the study of fungi Virology is the study of viruses Parasitology is the study of protozoa and parasitic worms  Modern Developments in Microbiology 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  Microbial Ecology Bacteria recycle carbon, nutrients, sulfur, and phosphorus that can be used by plants and animals (Beijerinck & Winogradsky)  MRSA Methicillin-resistant Staphylococcus aureus 1950s: Penicillin resistance developed 1980s: Methicillin resistance 1990s: MRSA resistance to vancomycin reported – VISA: vancomycin-intermediate-resistant S. aureus – VRSA: vancomycin-resistant S. aureus Bird Flu; Zika; SARS CoV-2 Virus; Monkey Pox