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Lecture 1 Intro to Microbiology: History and Taxonomy

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1 Lecture 1 Intro to Microbiology: History and Taxonomy

2 Microbiology The study of organisms to small to be seen without a microscope Includes living microorganisms: bacteria, algae, fungi, protozoa AND non-cellular infectious agents: viruses, viroids, prions

3 Why study Microorganisms?
Microorganisms are the foundation for all life on earth They effect your everyday life Only a minority of microorganisms are pathogenic Microorganisms are found almost everywhere

4 Microbes and Human Welfare
Recycle chemical elements Decompose organic matter Bioremediation Biotechnology Gene therapy Genetic engineering

5 Microbes can be used to clean up oil spills such as this one in Alaska
Courtesy of the Exxon Valdez Oil Spill Trustee Council/NOAA

6 Microbes and Human Disease
Everyone has microbes in and on body Person may or may not contract disease once they are in contact with it

7 Infectious Disease Pathogens invade susceptible host
Emerging infectious diseases Ebola BSE, Mad cow disease Know other emerging infectious diseases from book for exam

8 Major Groups of the Microbial World
Bacteria Archeae Fungi Algae Protozoans Helminths Viruses Major Features Small size Diverse appearance Diverse genetics

9 Bacteria

10 Archaea Found in extreme environments

11 Fungi

12 Fungi

13 Algae

14 Protozoa

15 Helminths

16 Viruses


18 The Spectrum of Microorganisms is Diverse
- There are over 10 million species of prokaryotes There are over 3600 known viruses There are about 70,000 described species of fungi

19 Discovery of Microorganisms
Robert Hooke published Micrographia (1665) Anton van Leeuwenhoek ( ) He peered at a drop of lake water through a lens that he carefully ground -

20 Hooke’s Micrographia © Library of Congress [LC-USZ ]

21 Cork cells © Library of Congress [LC-USZ ]

22 Anton van Leeuwenhoek Courtesy of Pfizer, Inc.

23 Leeuwenhoek’s drawings of bacteria
Courtesy of Royal Society, London


25 Next Question: Where did microorganisms originate?
Spontaneous generation: Life originates from non-life, believed from the time of Aristotle ( B.C.) Works of Redi, Pasteur, and Tyndall refute this theory Prove Germ Theory of Disease -

26 Francesco Redi ( ) Proponents of spontaneous generation believed that worms in rotting meat came from meat itself Redi debunked this theory Experiments with meat

27 New Experiments Needed to Refute Spontaneous Generation
Typical Experiment: used nutrient broth (infusion): contains nutrients needed for microorganisms to grow 1. boil to kill all forms of life 2. seal vessel If cloudy after standing: spontaneous generation If clear: no spontaneous generation Different investigators: Different results -

28 Louis Pasteur (1822-1894) Father of microbiology
Demonstrated air is filled with microorganisms Demonstrated that sterile infusions will stay sterile in specially constructed flasks even when they were left open to the air


30 John Tyndall Explained differences in results obtained from different laboratories Proved Pasteur correct He concluded that different infusions require different boiling times to be sterilized Because of heat resistant microorganisms: Endospores

31 Endospores Some microorganisms exist in two forms:
1. a cell that is readily killed by boiling 2. one that is heat resistant

32 Golden Age of Microbiology
Rapid advances by Pasteur and Robert Koch Discovery of agents of many diseases and role of immunity in prevention and cure of disease Discoveries include: Fermentation and pasteurization Germ theory of disease Vaccination

33 Fermentation and Pasteurization
Pasteur- why did wine sour? Believed at time, that converted sugars into alcohol Yeasts do the work of fermentation Bacteria cause spoilage Pasteurization

34 Germ Theory of Disease Pasteur: to fight silkworm disease
Ignaz Semmelweis: Instructed hospital staff to wash hands Lister: treated surgical wounds with phenol solution John Snow: Interviewed sick and healthy Londoners during cholera epidemic Robert Koch

35 Ignaz Semmelweiss encouraged hospital staff to wash their hands
Courtesy of Pfizer, Inc.

36 Robert Koch ( ) Demonstrated that anthrax caused by Bacillus anthracis Usual means of transmission: resistant endospores Introduced use of pure culture techniques for handling bacteria in lab Cultured bacteria on agar Discovered Mycobacterium tuberculosis – causative agent for tuberculosis Proved germ theory of disease

37 Vaccination Edward Jenner: Introduced vaccine for smallpox
Inoculate with fluid from cowpox blisters prevented smallpox

38 Modern developments in Microbiology
Bacteriology Mycology Parasitology Immunology Virology Recombinant DNA technology

39 Taxonomy

40 Taxonomy Involves three steps: 1. Identification 2. Classification
3. Nomenclature Objective is to arrange organisms into categories that reflect the similarities of the individuals within the groups 40

41 History Carolus Linnaeus: 1700’s: Two Kingdoms: Plants and Animals
Ernst Haekel: 1866: Kingdom Protista R.H. Whittaker: 1969: Five Kingdoms Carl Woese: 1990: Three Domains

42 Taxonomic Hierarchy Species: basic unit
Group of related species: strain Genus: group of similar species Family: group of similar genera, ends in - aceae Order: group of similar families, ends in - ales Class: group of similar orders, ends in - ia Phylum: group of similar classes Kingdom: group of similar Phyla Domain: group of similar Kingdoms 42


44 Domains of the Living World
Bacteria Archaea Eucarya Bacteria and Archaea look identical Also both are prokaryotes, however differ in chemical composition and are unrelated 44


46 Eucarya All members of living world that are not prokaryotes are in domain eukarya May be single celled or multi-cellular Always contain true membrane-bound nucleus and other internal organelles Far more complex than prokaryotes 46

47 Four Kingdoms within Domain Eukarya
Animalia Multicellular, heterotrophic Plantae Protista: many single celled eukaryotes Ex. Paramecium, algae, protozoa Fungi Single celled: yeast Multicellular: molds and mushrooms 47

48 Bacteria Single-celled prokaryotes
Most have specific shapes: cylindrical, spherical, and spiral Most have rigid cell walls Multiply by binary fission Many move using appendages - 48

49 Archaea Have same size, shape, and appearance as bacteria
Multiply by binary fission and move primarily with flagella Also have cell walls, but differ from bacteria: no peptidoglycan Interesting Feature: able to grow in extreme environments 49

50 Identification of Microorganisms
Microscopic examination Culture characteristics Biochemical tests Nucleic Acid Analysis Serological Tests Person’s symptoms also play a role 50

51 Classification of Microorganisms
Phenotype: Physical appearance Genotype: Genes Development of molecular techniques has made this possible Bergey’s Manual of Systematic Bacteriology All known species described here If properties of newly isolated organism do not agree with any description, considered new organism 51


53 Nomenclature International code for Nomenclature of Bacteria
Uses two-word naming system: Binomial Nomenclature First name is the Genus, capital Second name is the species, lower case Both are italicized Example: Escherichia coli, or E.coli Strains; minor differences with in species: E. coli strain B or E.coli strain K-12 53

54 Nonliving Members of Microbial World
In order to be considered alive, must be composed of one or more cells Viruses, Viroids, and prions are termed agents Viruses: Piece of nucleic acid surrounded by protein coat Can only multiply inside human host cells Obligate intercellular parasites - 54

55 Non-living members of the bacterial world
Viroids: Simpler than viruses Single short piece of RNA No protective coat Can only multiply inside cells Prions: Appear to only be protein without nucleic acid Possible another agent is causing the disease 55


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