Transcript Biology 230 Microbiology - Harford Community College

Lecture 1
Intro to Microbiology: History
and Taxonomy
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
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
Microbes and Human Welfare
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Recycle chemical elements
Decompose organic matter
Bioremediation
Biotechnology
Gene therapy
Genetic engineering
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
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
Infectious Disease
• Pathogens invade susceptible host
• Emerging infectious diseases
• Ebola
• BSE, Mad cow disease
• Know other emerging infectious diseases
from book for exam
Major Groups of the Microbial World
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Bacteria
Archeae
Fungi
Algae
Protozoans
Helminths
Viruses
8. Major Features
9. Small size
10. Diverse appearance
11. Diverse genetics
Bacteria
Archaea
• Found in extreme environments
Fungi
Fungi
Algae
Protozoa
Helminths
Viruses
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
Discovery of Microorganisms
• Robert Hooke published Micrographia
(1665)
• Anton van Leeuwenhoek (1632-1723)
• He peered at a drop of lake water through
a lens that he carefully ground
Hooke’s Micrographia
© Library of Congress [LC-USZ62-95187]
Cork cells
© Library of Congress [LC-USZ62-95187]
Anton van Leeuwenhoek
Courtesy of Pfizer, Inc.
Leeuwenhoek’s drawings of bacteria
Courtesy of Royal Society, London
Next Question: Where did
microorganisms originate?
• Spontaneous generation: Life originates
from non-life, believed from the time of
Aristotle (384-322 B.C.)
• Works of Redi, Pasteur, and Tyndall refute
this theory
• Prove Germ Theory of Disease
Francesco Redi (1626-1697)
• Proponents of spontaneous generation
believed that worms in rotting meat came
from meat itself
• Redi debunked this theory
• Experiments with meat
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
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
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
Endospores
• Some microorganisms exist in two forms:
– 1. a cell that is readily killed by boiling
– 2. one that is heat resistant
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
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
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
Ignaz Semmelweiss encouraged hospital staff to wash their hands
Courtesy of Pfizer, Inc.
Robert Koch (1843-1910)
• 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
Vaccination
• Edward Jenner:
• Introduced vaccine for smallpox
• Inoculate with fluid from cowpox blisters
prevented smallpox
Modern developments in
Microbiology
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Bacteriology
Mycology
Parasitology
Immunology
Virology
Recombinant DNA technology
Taxonomy
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
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
Taxonomic Hierarchy
• Species: basic unit
– Group of related species: strain
• Genus: group of similar species
• Family: group of similar genera, ends in - aceae
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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
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
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
Four Kingdoms within Domain
Eukarya
• Animalia
– Multicellular, heterotrophic
• Plantae
– Multicellular, heterotrophic
• Protista: many single celled eukaryotes
– Ex. Paramecium, algae, protozoa
• Fungi
– Single celled: yeast
– Multicellular: molds and mushrooms
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
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
Identification of Microorganisms
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Microscopic examination
Culture characteristics
Biochemical tests
Nucleic Acid Analysis
Serological Tests
Person’s symptoms also play a role
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
Nomenclature
• International code for Nomenclature of Bacteria
• Uses two-word naming system: Binomial
Nomenclature
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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
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
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