Chapter 1
• Microbiology is the study of microorganisms such as
• bacteria
• Archaea
• Viruses
• Fungi
• Protists
• Animals
Microorganisms:
• Decompose organic waste
• Are producers in the ecosystem by photosynthesis
• Produce industrial chemicals such as ethyl alcohol and
acetone
• Produce drugs
Microorganisms:
• Play a role in food/beverage production
• Are used to treat water
• Are used to clean up pollution
Knowledge of microorganisms:
• Allows humans to
• Prevent food spoilage
• Prevent and treat disease occurrence
• Make drugs
• Conduct research
• Etc.
• Knowledge of microorganisms led to aseptic
techniques to prevent contamination in medicine and in
microbiology laboratories.
Microorganisms
bacteria
protozoa
fungus
algae
virus
Naming and Classifying Microorganisms
• Carolus Linnaeus established the system of
scientific nomenclature in 1735.
• Each organism has two names: the genus name
and the species name.
• i.e. Staphylococcus aureus; Homo sapiens
• Scientific names:
• Are “Latinized” and used worldwide.
• May be descriptive or named after someone or
something.
Scientific names
• After the first use, scientific names may be abbreviated
with the first letter of the genus, and the species name:
• i.e. Staphylococcus aureus and Esherichia coli are
found in/on the human body. On the skin you may
find S. aureus, and E. coli lives in the large
intestine.
• Prokaryotes
Bacteria
• Peptidoglycan cell walls
• Binary fission
• For energy, use organic chemicals, inorganic
chemicals, or photosynthesis
• Vast majority do not cause human disease
Archaea:
• Prokaryotic
• Lack peptidoglycan
• Live in extreme environments
• Include:
• Methanogens
• Extreme halophiles
• Extreme thermophiles
• Not known to cause human disease
Fungi
• Eukaryotes
• Use organic substances for energy
• Molds and mushrooms are multicellular
• Yeasts are unicellular
Protozoa (Protists)
• Eukaryotes
• Absorb or ingest organic
substances
• May be motile via
pseudopods, cilia, or
flagella
Algae (Protists)
• Eukaryotes
• Use photosynthesis for
energy
• Produce molecular
oxygen and organic
compounds
Viruses
• Non-cellular
• Consist of DNA or RNA core
• Core is surrounded by a protein coat called capsid
• Capsid may be enclosed in a lipid envelope
• Viruses are replicated only when they are in a living
host cell
Multicellular Animal Parasites
• Eukaryote
• Multicellular animals
• Parasitic flatworms and
round worms are called
helminths.
• Microscopic stages in life
cycles.
Tapeworm
Classification of Organisms
• Three domains
• Bacteria
• Archaea
• Eukarya
• Protists
• Fungi
• Plants
• Animals
History of Microbiology
• Microbes have been on earth for billions of
years
• In 1665, Robert Hooke was first to observe
biological cells under a microscope (cork cells).
• The first live microbes were observed under a
microscope in 1673 by Antoni van
Leeuwenhoek.
• He observed microbes in teeth scrapings,
rain water, etc.
van Leeuwenhoek’s microscope
How is life created?
• The hypothesis that living organisms arise from
nonliving matter is called spontaneous generation.
• The Alternative hypothesis, that living organisms arise
from preexisting life, is called biogenesis.
Evidence against Spontaneous Generation
• 1668: Francisco Redi filled six jars with decaying
meat.
Conditions
Results
3 jars covered with fine net
No maggots
3 open jars
Maggots appeared
From where did the maggots come?
Evidence For Spontaneous Generation
• 1745: John Needham put boiled nutrient broth into
covered flasks.
Conditions
Results
Nutrient broth heated, then
Microbial growth
placed in sealed flask
From where did the microbes come?
Evidence against Spontaneous Generation
• 1765: Lazzaro Spallanzani boiled nutrient solutions in
flasks.
Conditions
Nutrient broth placed in flask,
heated, then sealed
Results
No microbial growth
Final Evidence against Spontaneous Generation
• 1861: Louis Pasteur
demonstrated that
microorganisms are
present in the air.
• Pasteur’s S-shaped flask
kept microbes out but let
air in.
The Golden Age of Microbiology
• 1857-1914
• Beginning with Pasteur’s work, discoveries
included the relationship between microbes
and disease, immunity, and antimicrobial drugs
Fermentation and Pasteurization
• Pasteur showed that microbes are responsible for
fermentation.
• Alcohol fermentation breaks down sugar to alcohol.
• We use this process to make beer and wine (yeast).
• Acetic acid fermentation breaks down alcohol to acetic
acid.
• We use this process to make vinegar. Some
bacteria can turn wine to vinegar.
Fermentation and Pasteurization
• Pasteur demonstrated that
“spoilage” bacteria could be
killed by heat.
• This application of high heat for
a short time is called
pasteurization.
The Germ Theory of Disease
• The idea that some diseases are caused by microbes.
• 1835: Agostino Bassi showed a silkworm disease was
caused by a fungus.
• 1865: Pasteur believed that another silkworm disease
was caused by a protozoan.
The Germ Theory of Disease
• 1840s: Ignaz Semmelwise advocated handwashing to
prevent transmission of puerperal fever from one
patient to another.
• 1860s: Joseph Lister used a chemical disinfectant to
prevent surgical wound infections.
• 1876: Robert Koch established a set of postulates,
used to prove that a specific microbe causes a specific
disease (i.e. anthrax).
Vaccination
• 1796: Edward Jenner inoculated a person with cowpox
virus. The person was then protected from smallpox.
• The term vaccination comes from vacca, latin for cow.
The Birth of Modern Chemotherapy
• Treatment with chemicals is chemotherapy.
• Chemotherapeutic agents used to treat infectious
disease can be synthetic drugs or antibiotics.
• Antibiotics are chemicals produced by living organisms
that inhibit growth of, or kill microbes.
• Synthetic drugs are laboratory-made.
• 1910: Paul Ehrlich developed a synthetic arsenic drug,
salvarsan, to treat syphilis.
The Birth of Modern Chemotherapy
• 1928: Alexander Fleming
discovered the first
antibiotic.
• He observed that
Penicillium fungus made
an antibiotic, penicillin,
that killed
Staphylococcus aureus.
• 1940s: Penicillin was
tested clinically and mass
produced.
Microbiology Related fields
• Bacteriology is the study of bacteria.
• Mycology is the study of fungi.
• Parasitology is the study of protozoa and parasitic
worms.
• Virology is the study of viruses.
• Immunology is the study of the immune system.
• Recombinant DNA technology: DNA from two or more
different sources are combined.
Microbes are beneficial
• Nutrient recycling
• Bacteria recycle carbon, nitrogen, oxygen, sulfur,
and phosphorus that can be used by plants and
animals.
• Bioremediation
• Bacteria degrade
organic matter in
sewage.
• Bacteria degrade or
detoxify pollutants
such as oil and
mercury
Biological Insecticides
• Some microbes infect, and are pathogenic to, insects.
• Used to prevent insect attack on many crops.
• An alternative to chemical pesticides.
• Bacillus thuringiensis infections are fatal in many
insects but harmless to other animals including
humans and to plants.
• Application: sprayed or genetically engineered plants
Biotechnology and Genetic Engineering
• Genetic engineering is a form of biotechnology.
• Through genetic engineering, bacteria and fungi can
produce a variety of proteins including vaccines and
enzymes.
• Missing or defective genes in human cells can be
replaced in gene therapy by using viruses.
• Genetically modified bacteria are used to protect crops
from insects and freezing.