Transcript Chapter 1
Chapter 1 A Brief History of Microbiology © 2012 Pearson Education Inc. Lecture prepared by Mindy Miller-Kittrell North Carolina State University Chapter 1 Assignment Note: Homework assignments are due at the exam • • • • Multiple Choice 1-10 Matching 1-12 Concept Map List Steps of Scientific Method in order and describe each one • Discuss Pasteur’s experiment with the swan necked flasks investigating spontaneous generation. How does it exemplify the first 4 steps of the scientific method. Be specific. What was the experimental group? Control group? Result? The Early Years of Microbiology • What Does Life Really Look Like? – Antoni van Leeuwenhoek (Dutch) – Began making and using simple microscopes – Often made a new microscope for each specimen – Examined water and visualized tiny animals, fungi, algae, and single-celled protozoa: “animalcules” – By end of 19th century, these organisms were called microorganisms © 2012 Pearson Education Inc. Figure 1.1 Antoni van Leeuwenhoek Figure 1.2 Reproduction of Leeuwenhoek’s microscope Lens Specimen holder Figure 1.3 The microbial world The Early Years of Microbiology • How Can Microbes Be Classified? – Carolus Linnaeus developed taxonomic system for grouping similar organisms together – Leeuwenhoek’s microorganisms grouped into six categories: – Bacteria – Archaea – Fungi – Protozoa – Algae – Small multicellular animals © 2012 Pearson Education Inc. The Early Years of Microbiology • Bacteria and Archaea – – – – – Unicellular and lack nuclei Much smaller than eukaryotes Found everywhere there is sufficient moisture Reproduce asexually Two kinds – Bacteria – cell walls contain peptidoglycan – Archaea – cell walls composed of polymers other than peptidoglycan © 2012 Pearson Education Inc. Figure 1.4 Cells of the bacterium Streptococcus Nucleus of Prokaryotic bacterial cells eukaryotic cheek cell The Early Years of Microbiology • Fungi – – – – Eukaryotic (have membrane-bound nucleus) Obtain food from other organisms Possess cell walls Include – Molds – multicellular; grow as long filaments; reproduce by sexual and asexual spores – Yeasts – unicellular; reproduce by budding or sexual spores © 2012 Pearson Education Inc. Figure 1.5 Fungi-overview The Early Years of Microbiology • Protozoa – Single-celled eukaryotes – Similar to animals in nutrient needs and cellular structure – Live freely in water; some live in animal hosts – Asexual (most) and sexual reproduction – Most are capable of locomotion by – Pseudopodia – Cilia – Flagella © 2012 Pearson Education Inc. Figure 1.6 Locomotive structures of protozoa-overview The Early Years of Microbiology • Algae – – – – Unicellular or multicellular Photosynthetic Simple reproductive structures Categorized on the basis of pigmentation, storage products, and composition of cell wall © 2012 Pearson Education Inc. Figure 1.7 Algae-overview Figure 1.8 An immature stage of a parasitic worm in blood Red blood cell Figure 1.9 Viruses infecting a bacterium Virus Bacterium Viruses assembling inside cell The Golden Age of Microbiology • Scientists searched for answers to four questions – Is spontaneous generation of microbial life possible? – What causes fermentation? – What causes disease? – How can we prevent infection and disease? © 2012 Pearson Education Inc. The Golden Age of Microbiology • Some thought living things arose from three processes – Asexual reproduction – Sexual reproduction – Nonliving matter • Aristotle proposed spontaneous generation (384-322 B.C.) – Living things can arise from nonliving matter © 2012 Pearson Education Inc. The Golden Age of Microbiology • Redi’s Experiments – When decaying meat was kept isolated from flies, maggots never developed – Meat exposed to flies was soon infested – As a result, scientists began to doubt Aristotle’s theory © 2012 Pearson Education Inc. Figure 1.10 Redi’s experiments: late 1600s Flask unsealed Flask sealed Flask covered with gauze The Golden Age of Microbiology • Needham’s Experiments – Scientists thought microbes, but not animals, could arise spontaneously – Needham’s experiments reinforced this idea © 2012 Pearson Education Inc. The Golden Age of Microbiology • Spallanzani’s Experiments – Conclusions – Needham failed to heat vials sufficiently to kill all microbes or had not sealed vials tightly enough – Microorganisms exist in air and can contaminate experiments – Spontaneous generation does not occur – Critics argued against experiments – Sealed vials did not allow enough air for organisms to survive – Prolonged heating destroyed “life force” © 2012 Pearson Education Inc. Figure 1.11 Louis Pasteur Pasteur Video • http://www.youtube.com/watch?v=0OmWbRK W4K8 The Golden Age of Microbiology • Pasteur’s Experiments – When the “swan-necked” flasks remained upright, no microbial growth appeared – When the flask was tilted, dust from the bend in the neck seeped back into the flask and made the infusion cloudy with microbes within a day © 2012 Pearson Education Inc. Figure 1.12 Pasteur’s experiments with “swan-necked” flasks Steam escapes from open end of flask. Infusion is heated. Air moves in and out of flask. Infusion sits; no microbes appear. Months Infusion remains sterile indefinitely. Dust from air settles in bend. The Golden Age of Microbiology • The Scientific Method *Identify Question Form Hypothesis Collect data by performing experiment *Interpret results Peer Review Publish Findings © 2012 Pearson Education Inc. If hypothesis is rejected The Golden Age of Microbiology • The Scientific Method: Pasteur’s experiment *Identify Question Form Hypothesis Collect data by performing experiment *Interpret results © 2012 Pearson Education Inc. Figure 1.13 The scientific method Observations Question Repeat Hypothesis Experiment, including control groups Modified hypothesis Experimental data support hypothesis Observations Experimental data do not support hypothesis Accept hypothesis Reject hypothesis Modify hypothesis Theory or law The Golden Age of Microbiology • What Causes Fermentation? – Spoiled wine threatened livelihood of vintners – Some believed air caused fermentation – Others insisted living organisms caused fermentation – Vintners funded research to prevent spoilage during fermentation – This debate also linked to debate over spontaneous generation © 2012 Pearson Education Inc. Figure 1.14 Pasteur's application of the scientific method Observation: Microscopic analysis shows juice contains yeasts and bacteria. Fermenting grape juice Hypothesis Experiment Observation Conclusion Day 1: Flasks of grape Day 2 juice are heated sufficiently to kill all microbes. I. Spontaneous fermentation occurs. II. Air ferments grape juice. III. Bacteria ferment grape juice into alcohol. IV. Yeasts ferment grape juice into alcohol. Flask is sealed. Flask remains open to air via curved neck. Juice in flask is inoculated with bacteria and sealed. Juice in flask is inoculated with yeast and sealed. No fermentation; juice remains free of microbes Reject hypothesis I. No fermentation; juice remains free of microbes Reject hypothesis II. Bacteria reproduce; acids are produced. Modify hypothesis III; bacteria ferment grape juice into acids. Yeasts reproduce; alcohol is produced. Accept hypothesis IV; yeasts ferment grape juice into alcohol. Table 1.1 Some Industrial Uses of Microbes The Golden Age of Microbiology • What Causes Disease? – Pasteur developed germ theory of disease – Robert Koch studied causative agents of disease – Anthrax – Examined colonies of microorganisms © 2012 Pearson Education Inc. Figure 1.15 Robert Koch The Golden Age of Microbiology • Koch’s Contributions – Simple staining techniques – First photomicrograph of bacteria – First photomicrograph of bacteria in diseased tissue – Techniques for estimating CFU/ml – Use of steam to sterilize media – Use of Petri dishes – Techniques to transfer bacteria – Bacteria as distinct species © 2012 Pearson Education Inc. Figure 1.16 Bacterial colonies on agar Bacterium 6 Bacterium 5 Bacterium 4 Bacterium 3 Bacterium 2 Bacterium 1 Bacterium 7 Bacterium 8 Bacterium 9 Bacterium 10 Bacterium 11 Bacterium 12 The Golden Age of Microbiology • Koch’s Postulates – Suspected causative agent must be found in every case of the disease and be absent from healthy hosts – Agent must be isolated and grown outside the host – When agent is introduced into a healthy, susceptible host, the host must get the disease – Same agent must be found in the diseased experimental host © 2012 Pearson Education Inc. Table 1.2 Other Notable Scientists of the “Golden Age of Microbiology” and the Agents of Disease They Discovered The Golden Age of Microbiology • Gram’s Stain – Danish scientist Hans Christian Gram developed more important staining technique than Koch’s in 1884 – Involves the applications of a series of dyes – Some microbes are left purple, now labeled Gram-positive – Other microbes are left pink, now labeled Gramnegative – Gram procedure used to separate into two groups © 2012 Pearson Education Inc. Figure 1.17 Results of Gram staining Gram-positive Gram-negative The Golden Age of Microbiology • How Can We Prevent Infection and Disease? – – – – – – Semmelweis and handwashing Lister’s antiseptic technique Nightingale and nursing Snow – infection control and epidemiology Jenner’s vaccine – field of immunology Ehrlich’s “magic bullets” – field of chemotherapy © 2012 Pearson Education Inc. Semmelweis and Lister video • http://www.youtube.com/watch?v=T73PYNyy eiI&feature=related Figure 1.18 Florence Nightingale Figure 1.19 Some scientific disciplines and applications BIOLOGISTS MODERN DISCIPLINES Leeuwenhoek Bacteriology (bacteria) Protozoology (protozoa) Mycology (fungi) Parasitology (protozoa and animals) Phycology (algae) Linnaeus Taxonomy Semmelweiss Snow Infection control Epidemiology Pre-1857 The Golden Age of Microbiology (1857–1907) Industrial microbiology Pasteur Pasteurization Microbial metabolism Genetics Genetic engineering Buchner Koch Food and beverage technology Koch’s postulates Etiology Ivanowski Virology Beijerinck Winogradsky Environmental microbiology Ecological microbiology Gram Microbial morphology Lister Nightingale Antiseptic medical techniques Hospital microbiology Jenner von Behring Kitasato Serology Immunology Ehrlich Chemotherapy Fleming Pharmaceutical microbiology Table 1.3 Fields of Microbiology The Modern Age of Microbiology • What Are the Basic Chemical Reactions of Life? – Biochemistry – Began with Pasteur’s and Buchner’s works – Microbes used as model systems for biochemical reactions – Practical applications – Design of herbicides and pesticides – Diagnosis of illness and monitoring responses to treatment – Treatment of metabolic diseases – Drug design © 2012 Pearson Education Inc. The Modern Age of Microbiology • How Do Genes Work? – – – – Microbial genetics Molecular biology Recombinant DNA technology Gene therapy © 2012 Pearson Education Inc. The Modern Age of Microbiology • Microbial Genetics – Avery, MacLeod, and McCarty: genes are contained in molecules of DNA – Beadle and Tatum: a gene’s activity is related to protein function – Translation of genetic information into protein explained – Rates and mechanisms of genetic mutation investigated – Control of genetic expression by cells described © 2012 Pearson Education Inc. The Modern Age of Microbiology • Molecular Biology – Explanation of cell function at the molecular level – Pauling proposed that gene sequences could – Provide understanding of evolutionary relationships/processes – Establish taxonomic categories – Identify microbes that have never been cultured – Woese determined cells belong to bacteria, archaea, or eukaryotes – Cat scratch disease caused by unculturable organism © 2012 Pearson Education Inc. The Modern Age of Microbiology • Recombinant DNA Technology – Genes in microbes, plants, and animals manipulated for practical applications – Production of human blood-clotting factor by E. coli to aid hemophiliacs • Gene Therapy – Inserting a missing gene or repairing a defective one in humans by inserting desired gene into host cells © 2012 Pearson Education Inc. The Modern Age of Microbiology • What Roles Do Microorganisms Play in the Environment? – Bioremediation uses living bacteria, fungi, and algae to detoxify polluted environments – Recycling of chemicals such as carbon, nitrogen, and sulfur © 2012 Pearson Education Inc. The Modern Age of Microbiology • How Do We Defend Against Disease? – Serology – The study of blood serum – Blood contains chemicals and cells that fight infection – Immunology – The study of the body’s defense against specific pathogens – Chemotherapy – Fleming discovered penicillin – Domagk discovered sulfa drugs © 2012 Pearson Education Inc. Figure 1.20 Effects of penicillin on a bacterial “lawn” in a petri dish Fungus colony (Penicillium) Zone of inhibition Bacterial colonies (Staphylococcus) The Modern Age of Microbiology • What Will the Future Hold? – Microbiology is built on asking and answering questions – The more questions we answer, the more questions we have © 2012 Pearson Education Inc.