Transcript Chapter 1 Introduction to Microbiology

Chapter 1
Introduction
• Ubiquitous – they are everywhere
• Air, water, Soil ( microbes are all around
us)
• Normal flora – found in the gastrointestinal
tract, genitourinary tract, respiratory tract,
skin.
• Beneficial aspects and harmful aspects
• Normal flora protect us from diseases.
They suppress the growth of pathogens.
• E. coli in the large intestine makes vitamin
K – used for blood clotting.
• Aquatic environments. Unicellular algae –
bottom of the food chain.
• Unicellular algae > tiny fish > large fish >
shark.
• Algae are autotrophs. They use CO2 and
water to make sugar.
• Soil microbes are involved in recycling
chemical elements.
• Breakdown cellulose and release CO2.
• Making food products (yogurt, cheese,
bread). Yeast + flour > dough
• Small ball of dough -----large ball of dough
• Therapeutic substances – genetic
engineering is used to force E. coli to
make human insulin.
• Bioremediation – microbes are used to
clean up chemical pollutants (oil spills) in
the environment.
• Insecticide – BT toxin is sprayed on plants.
• Sewage treatment – breakdown organic
matter to produce methane.
• Harmful aspects
• Tuberculosis, Lyme disease
• Spoilage of food products.
Milk ----- sour. Lactose --- acids.
• History of microbiology
• 1665 Robert Hooke – plant materials
(leaves and stems). Little boxes – cells.
• 1673 – 1723 Anton van Leeuwenhoek
observe microbes under the microscope.
• Rain water, scrapings from his teeth.
• Called the microbes animalcules.
• Spontaneous generation theory – life
could arise from nonliving matter.
• Decaying meat give birth to maggots
(larvae of flies)
Fine net
No maggots
Needham 1745
• Rudolph Virchow – theory of biogenesis.
• Life could arise only from pre-existing
living cells.
• 1861 Louis Pasteur disproved the
spontaneous generation theory.
Pasteur’s experiment
S shaped curve
S shaped curveS shaped curve
S shaped curve
• Microbes are found in the air, in liquids
and on solids.
• Foundation for the aseptic procedure used
in the lab to prevent contamination
• 1857 – discovered fermentation.
• Yeast converted sugars in the grapes to
alcohol and CO2 in the absence of O2.
• 1864 – came up with pasteurization.
Beverages such as milk are heated
enough to kill microbes without destroying
the flavor of the beverages.
Germ theory of disease
• A belief microbes could cause diseases.
• 1860s Joseph Lister treated surgical
wounds with disinfectant.
• 1876 Robert Koch proved the germ theory
of disease.
• Animals such as cattle were dying of a
disease.
• Drew blood from the animals that had died
of the disease.
• Isolated a rod-shaped bacterium (isolate
#1)
• Grew bacterium in the lab and obtained a
pure culture of the bacterium.
• Injected bacterium into healthy animals.
• They got sick and died. He isolated rod
shaped bacterium from these animals
(isolate #2)
• Compared the 2 isolates and found that
they were identical.
• Anthrax. Bacillus anthracis.
• The above steps are known as Koch’s
postulates.
• They are used even today to determine
the causative agent of a mysterious
infectious disease.
• 1928 Alexander Fleming discovered
penicillin.
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Naming organisms
1735 Carolus Linnaeus – binomial
Genus and species
Latin – describe the organism, honor a
scientist.
• Staphylococcus aureus
• Escherichia coli
Diversity of Microorganisms
• Bacteria – prokaryotic
• Pre-nucleus – DNA is NOT surrounded by
a membrane
• Unicellular
• Heterotroph – get energy from organic
molecules.
• Cell walls - peptidoglycan
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Fungi – yeasts and molds
Eukaryotic – true nucleus
Unicellular/multicellular
Cell walls – chitin
All are heterotrophs
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Protozoa – eukaryotic
Unicellular
Heterotophs
Algae – eukaryotic
Unicellular/multicellular
Autotrophs - photosynthesize
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Viruses – acellular
Either have DNA or RNA
Obligate intracellular parasites
Helminths – multicellular
Worms
Eggs are microscopic
Classification of organisms
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1969 Robert whittaker
5 kingdom system
Classification based on
Cell type - prokaryotic/eukaryotic
Cellular organization –
unicellular/multicellular
• Nutritional requirements –
photosynthetic/nonphotosynthetic
Classification of organisms
• Prokaryotae (monera) – prokaryotic
organisms – bacteria
• Protista - protozoa
• Fungi – Yeasts and molds
• Plant – ferns, trees, flowering plants
• Animal – worms, insects, vertebrates
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3 domains
Ribosomal RNA sequence
Archaea, Bacteria, Eukarya
Bacteria – prokaryotic
Normal flora, pathogens
Peptidoglycan
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Archaea
Prokaryotic
Unusual, extreme environments
Salt lakes, dead sea
Do not have peptidoglycan cell wall
pseudomurein
• Eukarya
• All the eukaryotic organisms
• Protozoa, fungi, plants and animals