Chapter 1 A Brief History of Microbiology The

Chapter 1 A Brief History of Microbiology

The Early Years of Microbiology • What Does Life Really Look Like? • Antoni van Leeuwenhoek (Dutch) – 1632 -1723 • Became founder of protozoology and bacteriology • 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 19 th century, these organisms were called microorganisms © 2012 Pearson Education Inc.

• How Can Microbes Be Classified? • Carolus Linnaeus developed taxonomic system for grouping similar organisms together • Domain Archaea • Prokaryotic, includes “extremophile” bacteria • Domain Bacteria • Prokaryotic, includes organisms once in Kingdom Monera • Domain Eukarya • Eukaryotic; protists, fungi, plants, animals © 2012 Pearson Education Inc.

• Microorganisms grouped into six categories: • Bacteria • Archaea • Fungi • Protozoa • Algae • Small multicellular animals

• Bacteria and Archaea – The Prokaryotes • Unicellular and lack nuclei • Much smaller than eukaryotes • Found everywhere there is sufficient moisture • Where you find life, you will find a prokaryote (you may not find a eukaryote) • Reproduce asexually • Two kinds • Bacteria – cell walls contain peptidoglycan • Archaea – cell walls composed of polymers other than peptidoglycan • Include the extremophile bacteria © 2012 Pearson Education Inc.

• Fungi • • Eukaryotic (have membrane-bound nucleus) Obtain food from other organisms - heterotrohic Cell walls made of chitin 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.

• Protists • Eukaryotic • Formerly Kingdom Protista • 2 types: • Algae – photosynthetic • Include phytoplankton and seaweed • Protozoans - heterotrophic

• Algae (formerly in Kingdom Protista) Unicellular (phytoplankton) or multicellular (seaweed) Photosynthetic Simple reproductive structures Categorized on the basis of pigmentation, storage products, and composition of cell wall • These do not cause disease • • • However, they can be of medical importance: • Some produce a toxin that can cause problems during an algal bloom • Some produce compounds that are used to make medicinal products © 2012 Pearson Education Inc.

• Protozoa (formerly in Kingdom Protista) • 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.

• Some animals cause disease: • Arthropods • Flatworms • Round worms • Some are small and can only be seen and/or diagnosed using micro methods

• Early on, 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.

• 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 • People observed maggots just “appeared” on meat © 2012 Pearson Education Inc.

• 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 • The maggots didn’t spontaneously generate, they were the larvae of the flies that landed on the meat and had laid microscopic eggs © 2012 Pearson Education Inc.

• Needham’s Experiments • Some scientists still thought microbes, but not animals, could arise spontaneously • Needham’s experiments reinforced this idea • He would heat broth and then cork bottle, microbial growth showed up later • Thought that this proved spontaneous generation • BUT – did he heat broth enough? , did microbes enter the bottles before they were corked? © 2012 Pearson Education Inc.

• Spallanzani’s Experiments • Sealed vials, then boiled • No microbial growth • Critics argued against experiments • Sealed vials did not allow enough air for organisms to survive • Prolonged heating might have destroyed “life force” © 2012 Pearson Education Inc.

• 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.

• 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 support or disprove hypothesis • If it is disproven, go on to test other hypotheses • If multiple hypotheses are support with lots of data and the scientific community, can lead to theory or law • Biology does not have Laws, they have theories, why? © 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

• 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 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

• What Causes Disease? • Pasteur developed germ theory of disease • Microorganisms are the cause of disease • Robert Koch studied causative agents of disease • Anthrax • Examined colonies of microorganisms • Developed Koch’s postulates © 2012 Pearson Education Inc.

• Koch’s Contributions – Founder of Microbiology • • Simple staining techniques 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

• 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

• 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 Gram-negative • Gram procedure used to separate into two groups © 2012 Pearson Education Inc.

• How Can We Prevent Infection and Disease? • Semmelweis and handwashing • Washing hands between patients • Lister’s antiseptic technique • Spraying wound with chemical that also reduced smell in sewage • Aseptic technique • Nightingale and nursing • Nurse that introduced hygiene standards • Snow – infection control and epidemiology • Mapped spread of cholera • Jenner’s vaccine – field of immunology • Milkmaids exposed to cowpox did not develop smallpox • Ehrlich’s “magic bullets” – field of chemotherapy • Finding compounds that would kill microorganism but not person © 2012 Pearson Education Inc.

Figure 1. 19 Some BIOLOGISTS scientific disciplines and applications 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 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

• 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.

• How Do Genes Work? • Scientists studying microbes made most of the great advances in genetics • Microbial genetics • Gene activity is related to function of protein coded by that gene • Mutation rates • Molecular biology • Biochemistry, cell biology, and genetics to explain cell function at molecular level • Gene sequencing • Recombinant DNA technology • Genetic engineering • Gene therapy • Using recombinant DNA technology to repair defective gene © 2012 Pearson Education Inc.

• Microbial Genetics • Avery, Mac. Leod, and Mc. Carty: 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.

• 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.

• 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.

• 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 • Environmental Microbiology • Nitrogen cycle • Sulfur cycle © 2012 Pearson Education Inc.

• How Do We Defend Against Disease? • Immunology • The study of the body’s defense against specific pathogens • Serology • The study of blood serum • Blood contains chemicals and cells that fight infection • 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)