MICROBIOLOGY
Introduction & Classification
Topics
•
•
•
•
•
•
•
Classification
Methods of Microbiology
Nutrition & Growth
Microbial Structure
Metabolism
Host parasite relationships
Control of Growth
Types of Microorganisms
• Bacteria
– Gram positive & gram negative
• Viruses
– RNA & DNA
• Fungi
– Yeasts & molds
• Protozoa
History
• Robert Hooke
– Described units in cork as cells
Anton van Leeuwenhoek-1667
– Made lenses or simple microscopes
Spontaneous Generation
• Abiogenesis-living matter arising from
nonliving matter
• Redi –maggots & meat
• Pasteur et al disproved abiogenesis
Pasteur
• Fermentation
– Yeast ferment grape juice –alcohol
– Bacteria ferment grape juice-acids
• Pasteurization
Germ Theory of Disease
• Koch
– Koch’s postulates
– Developed pure culture techniques
– Discovered TB agent
Immunology/Chemotherapy
• Jenner and smallpox vaccine
– Used cowpox virus
Antiseptics
• Semmelweis
• Lister
Fleming
• Discovered penicillin
Taxonomy
• System of cataloging organisms
– Identification: characterization of organisms
– Classification: arrangement of organisms into
similar groups
– Nomenclature: assign names
Binominal Nomenclature
• Genus-capitalized ; collection of species
• Microbes – species can be subdivided into
strains
• Strains have small genetic differences
Rules
• Both genus & species underlined or
italicized
• Strain-subdivision of species
– ID by name, number or letter
– Example- Escherichia coli- E. coli K12
Classification
• Wittaker-5 kingdoms
– Plants
– Animals
– Fungi
– Protista
– Monera or Prokaryote
Domains
• Carl Woese-1980s
• Based upon modern techniques
– Sequence of rRNA in ribosomes
• Three cell types based upon ribosomes
Three Domains
• Domains above kingdom level
• Bacteria or Eubacteriae
– Prokaryotes with peptidoglycan in cell wall
– Divide by binary fission
– Motile by flagella or cilia
– Sensitive to antibiotics
Archaea
• Ancient prokaryotes
– Cell wall present, not peptidoglycan
– Live in extreme environments
– Have unusual metabolic processes
– Not sensitive to antibiotics
Archaea
• Methanogens -strict anaerobes
– Produce methane from CO2 + H2
– Live in anaerobic mud lakes
– Intestine of cows
Archaea
• Halophiles
– Require high concentration of salt
• Maintain cell wall
– Spoilage of food-salted fish
– Salt lakes
Archaea
• Thermophiles
– Live in hot sulfurous waters or acidic water
– Nucleic acids/proteins do not function at low
temperatures
– Volcanic vents in ocean
Eukarya
•
•
•
•
•
•
All eukaryotes
Cell wall varies in composition
Not sensitive to antibiotics
Fungi-yeasts and molds
Protists-slime molds, protozoa, & algae
Plants & animals
Endosymbiotic Theory
• Eukaryotes evolved from prokaryotes
• Supported by similarities between prokaryotes &
organelles in eukaryotes
• Mitochondria & chloroplasts same size as
prokaryote cell
– Contain DNA, 70S ribosomes
• Endosymbiont-organism that lives within another
Support for Theory
»
•
•
•
•
•
Prokary
DNA
circular
Histones
No
Ribosomes 70S
Growth
binary
Cyanophora
Eukary
linear
Yes
80S
mitosis
Mitoch & Chloro
circular
No
70S
binary
Viruses
• Obligate intracellular parasites
• Not cells so non living agent
• No ribosomes
• Classification is different
Viroids & Prions
• Viroids
– Single short piece of RNA
– Cause disease in plants
– ? In humans
• Prions
– Protein
– Cause neurodegenerate diseases
– Humans & animals
– CJD & mad cow
New Challenges
• Antibiotic resistance
– MRSA, VRE & ESBL
• Emerging diseases
– SARS & Avian Influenza
• Bioterrorism
– Anthrax, smallpox, plague, botulism