Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Globalization and disease wikipedia , lookup
Infection control wikipedia , lookup
Bacterial morphological plasticity wikipedia , lookup
Bacterial cell structure wikipedia , lookup
Triclocarban wikipedia , lookup
Microorganism wikipedia , lookup
Disinfectant wikipedia , lookup
Human microbiota wikipedia , lookup
Bacterial taxonomy wikipedia , lookup
Chapter 1 A Brief History of Microbiology © 2012 Pearson Education Inc. Lecture prepared by Mindy Miller-Kittrell North Carolina State University “We used to see from the elephant down to the mite; thenceforth we had a world populated with tiny animalcules to whom the mite was elephant.” -F. Gonzales-Crussi The Early Years of Microbiology • What Does Life Really Look Like? – Antoni van Leeuwenhoek (Dutch, late 1600s) – 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 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. Classification • 3 Domains: – Domain Bacteria – Domain Archaea – Domain Eukarya – 4 Kingdoms – Kingdom Animalia – Kingdom Plantae – Kingdom Fungi – Kingdom Protista 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 in kingdom Protista. – 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 – 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 Flask unsealed Flask sealed Flask covered with gauze The Golden Age of Microbiology • Needham’s Experiments – Scientists now thought microbes, but not animals, could arise spontaneously – Needham’s experiments reinforced this idea – He boiled flasks of gravy and corked them. Microorganisms were later found to be in the gravy, demonstrating spontaneous generation. © 2012 Pearson Education Inc. The Golden Age of Microbiology • Spallanzani’s (1729-1799) Experiments – Conclusions – Needham failed to heat vials sufficiently to kill all microbes and had not sealed vials tightly enough – Microorganisms exist in air and can contaminate experiments – Spontaneous generation does not occur – Critics argued against Spallanzani’s 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 The Golden Age of Microbiology • Pasteur’s (1822-1895) 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 – Spontaneous generation debate led in part to scientific method – Observation leads to question – Question generates hypothesis – Hypothesis is tested through experiment(s) – Results prove or disprove hypothesis – Accepted hypothesis leads to theory/law – Reject or modify hypothesis © 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 (1843-1910) studied causative agents of disease – Anthrax – Also determined that anthrax can form endospores that allow them to survive harsh conditions. – Examined colonies of microorganisms growing on potatoes—pure cultures. – Discovered the causative agent of tuberculosis. © 2012 Pearson Education Inc. Figure 1.15 Robert Koch 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. The Golden Age of Microbiology • How Can We Prevent Infection and Disease? – Semmelweis and handwashing – Ignaz Semmelweis required medical students to wash their hands between procedures, greatly reducing the incidence of women contracting puerperal fever during childbirth. – Lister’s antiseptic technique – First to use antiseptics during surgery. © 2012 Pearson Education Inc. How Can We Prevent Infection and Disease? – Nightingale and nursing – Florence Nightingale was a nurse who emphasized cleanliness in hospitals. – Snow – infection control and epidemiology – Jenner’s vaccine – field of immunology – Edward Jenner developed the first vaccine. It was for smallpox John Snow (1813-1858) and cholera • John Snow is considered the father of epidemiology. • He went door to door in London and realized that people who were contracting cholera were getting their water from a contaminated source and he eventually convinced city officials to remove the handle from the pump, which helped end the cholera epidemic. Two competing theories Miasma Theory • Most people and scientists held to this. • Disease is caused by “bad air.” Germ Theory • Took a while to be accepted. John Snow’s map Guess what this is. Vibrio cholerae • Causative agent was isolated by Robert Koch in 1883. • He actually wasn’t the first to isolate it, but he received credit for it. Paul Ehrlich • “We must learn to shoot microbes with magic bullets.” • Developed the first chemotherapeutic agent. • It was called salvarsan and was used to treat syphilis. Paul Ehrlich • Ehrlich began his work studying various dyes. • He was pals with Robert Koch and showed Koch how to stain the bacteria that causes tuberculosis. The Modern Age of Microbiology • The “Golden Age of Microbiology” yielded many important discoveries and opened several new fields such as immunology, epidemiology, chemotherapy, and genetic engineering. • Scientists had a grand hope that they would be able to eliminate microbial disease. • This has proven more difficult than previously thought. • Why? The Modern Age of Microbiology • How Do Genes Work? – Microbial genetics – Molecular biology – Recombinant DNA technology © 2012 Pearson Education Inc. The Modern Age of Microbiology • How Do We Defend Against Disease? –Immunology – The study of the body’s defense against specific pathogens –Chemotherapy – Alexander Fleming discovered penicillin © 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.