A Brief History of Microbiology

Transcription

1 PowerPoint Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 1 A Brief History of Microbiology

2 The Early Years of Microbiology What Does Life Really Look Like? Antoni van Leeuwenhoek 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.

3 Figure 1.1 Antoni van Leeuwenhoek.

4 Figure 1.2 Reproduction of Leeuwenhoek s microscope.

5 Figure 1.3 The microbial world.

6 The Early Years of Microbiology How Can Microbes Be Classified? Carolus Linnaeus developed a taxonomic system for naming plants and animals and grouping similar organisms together. Leeuwenhoek s microorganisms can be grouped into six categories: Bacteria Archaea Fungi Protozoa Algae Small multicellular animals

7 The Early Years of Microbiology How Can Microbes Be Classified? Bacteria and Archaea Unicellular and lack nuclei Much smaller than eukaryotes Found everywhere there is sufficient moisture; some isolated in extreme environments Reproduce asexually Bacterial cell walls contain peptidoglycan, though some lack cell walls. Archaeal cell walls are composed of polymers rather than peptidoglycan.

8 Figure 1.4 Cells of the bacterium Streptococcus (dark blue) and two human cheek cells.

9 The Early Years of Microbiology How Can Microbes Be Classified? 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 asexually by budding; some produce sexual spores

10 Figure 1.5 Fungi.

11 The Early Years of Microbiology How Can Microbes Be Classified? Protozoa Single-celled eukaryotes Similar to animals in nutrient needs and cellular structure Live freely in water; some live in animal hosts Asexual (mostly) and sexual reproduction Most are capable of locomotion by: Pseudopods cell extensions that flow in direction of travel Cilia numerous short protrusions that propel organisms through its environment Flagella extensions of a cell that are fewer, longer, and more whiplike than cilia

12 Figure 1.6 Locomotive structures of protozoa.

13 The Early Years of Microbiology How Can Microbes Be Classified? Algae Unicellular or multicellular Photosynthetic Simple reproductive structures Categorized on the basis of pigmentation and composition of cell wall

14 Figure 1.7 Algae.

15 The Early Years of Microbiology How Can Microbes Be Classified? Other organisms of importance to microbiologists Parasites Viruses

16 Figure 1.8 An immature stage of a parasitic worm in blood.

17 Figure 1.9 A colorized electron microscope image of viruses infecting a bacterium.

18 The Early Years of Microbiology Tell Me Why Some people consider Leeuwenhoek the Father of Microbiology. Explain why this moniker makes sense.

19 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?

20 The Golden Age of Microbiology Does Microbial Life Spontaneously Generate? Some philosophers and scientists of the past thought living things arose from three processes: Asexual reproduction Sexual reproduction Nonliving matter Aristotle proposed spontaneous generation. Living things can arise from nonliving matter.

21 The Golden Age of Microbiology Does Microbial Life Spontaneously Generate? 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.

22 Figure 1.10 Redi s experiments.

23 The Golden Age of Microbiology Does Microbial Life Spontaneously Generate? Needham s experiments Scientists agreed that large animals could not arise spontaneously, but believed microbes could. Needham s experiments with beef gravy and infusions of plant material reinforced this idea.

24 The Golden Age of Microbiology Does Microbial Life Spontaneously Generate? Spallanzani s experiments His experiments contradicted Needham s findings. Concluded that: Needham failed to heat vials sufficiently to kill all microbes or had not sealed them tightly enough. Microorganisms exist in air and can contaminate experiments. Spontaneous generation of microorganisms does not occur; all living things arise from other living things. Critics said sealed vials did not allow enough air for organisms to survive and that prolonged heating destroyed the life force.

25 Figure 1.11 Louis Pasteur.

26 The Golden Age of Microbiology Does Microbial Life Spontaneously Generate? Pasteur s experiments Performed experiments with swan-necked flasks When the 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.

27 Figure 1.12 Pasteur s experiments with swan-necked flasks.

28 The Golden Age of Microbiology Does Microbial Life Spontaneously Generate? The scientific method Debate over spontaneous generation led in part to development of 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 Disproved hypothesis is rejected or modified

29 Figure 1.13 The scientific method, which forms a framework for scientific research.

30 The Golden Age of Microbiology Dr. Bauman s Microbiology Video Tutor For more information, listen to Dr. Bauman describe the steps of the scientific method and discuss several examples.

31 The Golden Age of Microbiology What Causes Fermentation? Spoiled wine threatened livelihood of many grape growers. Wine makers funded research of methods to promote production of alcohol and prevent spoilage during fermentation. The debate over the cause of fermentation reactions was also linked to the debate over spontaneous generation.

32 The Golden Age of Microbiology What Causes Fermentation? Pasteur s experiments Some scientists believed air caused fermentation; others insisted that living organisms caused fermentation. Pasteur conducted a series of experiments that addressed the cause of fermentation.

33 Figure 1.14 How Pasteur applied the scientific method in investigating the nature of fermentation.

34 The Golden Age of Microbiology What Causes Fermentation? Pasteur s experiments Led to the development of pasteurization Process of heating liquids just enough to kill most bacteria Began the field of industrial microbiology Intentional use of microbes for manufacturing products

35 Table 1.1 Some Industrial Uses of Microbes

36 The Golden Age of Microbiology What Causes Fermentation? Buchner s experiments Demonstrated fermentation does not require living cells Showed enzymes promote chemical reactions Buchner s work began the field of biochemistry.

37 The Golden Age of Microbiology What Causes Disease? Pasteur developed the germ theory of disease. Some diseases caused by specific germs called pathogens

38 Figure 1.15 Robert Koch.

39 The Golden Age of Microbiology What Causes Disease? Koch s experiments Robert Koch studied causative agents of disease (etiology). Demonstrated a bacterium causes anthrax Examined colonies of microorganisms

40 The Golden Age of Microbiology What Causes Disease? Koch s experiments Simple staining techniques First photomicrograph of bacteria First photograph of bacteria in diseased tissue Techniques for estimating bacterial number in a solution Use of steam to sterilize growth media Use of Petri dishes Laboratory techniques to transfer bacteria Bacteria as distinct species

41 Figure 1.16 Bacterial colonies on a solid surface (agar).

42 The Golden Age of Microbiology What Causes Disease? 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 to a healthy, susceptible host, the host must get the disease. Same agent must be found in the diseased experimental host.

43 Table 1.2 Other Notable Scientists of the Golden Age of Microbiology and the Agents of Disease They Discovered

44 The Golden Age of Microbiology What Causes Disease? Gram s stain The most widely used staining technique One of the first steps to identify a bacterium

45 Figure 1.17 Results of Gram staining.

46 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

47 Figure 1.18 Florence Nightingale.

48 Figure 1.19 Some of the many scientific disciplines and applications that arose from the pioneering work of scientists just before and around the time of the Golden Age of Microbiology.

49 The Golden Age of Microbiology Tell Me Why Some people consider Pasteur or Koch to be the Father of Microbiology, rather than Leeuwenhoek. Why might they be correct?

50 Table 1.3 Fields of Microbiology (1 of 2)

51 Table 1.3 Fields of Microbiology (2 of 2)

52 The Modern Age of Microbiology What Are the Basic Chemical Reactions of Life? Biochemistry Began with Pasteur s work on fermentation and Buchner s discovery of enzymes in yeast extract Kluyver and van Niel microbes used as model systems for biochemical reactions Practical applications: Design of herbicides and pesticides Diagnosis of illnesses and monitoring of patients responses to treatment Treatment of metabolic diseases Drug design

53 The Modern Age of Microbiology How Do Genes Work? Microbial genetics Molecular biology Recombinant DNA technology Gene therapy

54 The Modern Age of Microbiology How Do Genes Work? Microbial genetics Avery, MacLeod, and McCarty determined genes are contained in molecules of DNA. Beadle and Tatum established that a gene s activity is related to protein function. Translation of genetic information into protein explained Rates and mechanisms of genetic mutation investigated Identify methods cells use to control genetic expression

55 The Modern Age of Microbiology How Do Genes Work? Molecular biology Explanation of cell function at the molecular level Pauling proposed that gene sequences could: Provide understanding of evolutionary relationships and processes Establish taxonomic categories to reflect these relationships Identify existence of microbes that have never been cultured Woese and Fox determined cells can be categorized as bacteria, archaea, or eukaryotes. Cat scratch disease caused by unculturable organism

56 The Modern Age of Microbiology How Do Genes Work? 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

57 The Modern Age of Microbiology What Role 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 Causation of disease

58 The Modern Age of Microbiology How Do We Defend Against Disease? Serology The study of blood serum Von Behring and Kitasato existence in the blood of chemicals and cells that fight infection Immunology The study of the body s defenses against specific pathogens Chemotherapy Fleming discovered penicillin. Domagk discovered sulfa drugs.

59 Figure 1.20 The effects of penicillin on a bacterial lawn in a Petri dish.

60 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.

61 The Modern Age of Microbiology Tell Me Why Why are so many modern questions in microbiology related to genetics?