Chapter 1

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20 Φεβ 2013 (πριν από 4 χρόνια και 8 μήνες)

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Chapter 1


Microbiology is the study of microorganisms such as



bacteria



Archaea



Viruses



Fungi



Protists



Animals


Decompose organic waste




Are producers in the ecosystem by photosynthesis




Produce industrial chemicals such as ethyl alcohol and
acetone




Produce drugs

Microorganisms
:

Microorganisms
:


Play a role in food/beverage production





Are used to treat water





Are used to clean up pollution



Allows humans to


Prevent food spoilage





Prevent and treat disease occurrence




Make drugs


Knowledge of microorganisms
:


Conduct research






Etc.




Knowledge of microorganisms led to aseptic
techniques to prevent contamination in medicine and in
microbiology laboratories.


Microorganisms

bacteria

fungus

protozoa

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.



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.

Scientific names


Prokaryotes



Peptidoglycan cell walls




Binary fission



For energy, use organic chemicals, inorganic
chemicals, or photosynthesis




Vast majority do not cause human disease

Bacteria


Prokaryotic


Lack peptidoglycan


Live in extreme environments


Include:


Methanogens



Extreme halophiles



Extreme thermophiles



Not known to cause human disease

Archaea:


Eukaryotes



Use organic substances for energy




Molds and mushrooms are
multicellular




Yeasts are
unicellular

Fungi


Eukaryotes


Absorb or ingest organic
substances






May be motile via
pseudopods, cilia, or
flagella

Protozoa (Protists)


Eukaryotes


Use photosynthesis for
energy





Produce molecular
oxygen and organic
compounds

Algae (Protists)


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

Viruses

Multicellular Animal Parasites


Eukaryote


Multicellular animals


Parasitic flatworms and
round worms are called
helminths.


Microscopic stages in life
cycles.

Tapeworm


Three domains


Bacteria


Archaea


Eukarya


Protists


Fungi


Plants


Animals

Classification of Organisms

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


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
.

How is life created?


1668: Francisco Redi filled six jars with decaying
meat.

Evidence against Spontaneous Generation

Conditions

Results

3 jars covered with fine net

No maggots

3 open jars

Maggots appeared

From where did the maggots come?


1745: John Needham put boiled nutrient broth into
covered flasks.

Evidence For Spontaneous Generation

Conditions

Results

Nutrient broth heated, then
placed in sealed flask

Microbial growth

From where did the microbes come?


1765: Lazzaro Spallanzani boiled nutrient solutions in
flasks.

Evidence against Spontaneous Generation

Conditions

Results

Nutrient broth placed in flask,
heated, then sealed

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


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.

Fermentation and Pasteurization


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).

The Germ Theory of Disease


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.

Vaccination


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.

The Birth of Modern Chemotherapy


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.

Microbiology Related fields

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


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

Biological Insecticides


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.

Biotechnology and Genetic Engineering