MCB 2010C
Chapter 1
What is Microbiology?
Micro - too small to be seen with the naked eye
Bio – life
-ology - study of
“Brain-eating bug”
“Researchers target Florida's killer
amoeba” …Orlando Sentinel April 06 2011
Life Cycle Stages of Naegleria fowleri
• We have identified most microbes.
• Most microbes are potentially harmful to
humans or animals.
• When we are healthy, our bodies do not
contain any microbes
Diverse group of organisms
Small size (Most are microscopic)
Relative simplicity of structure and organization
Can be single-celled or multi-cellular
Perform same functional activities as “higher “
multicellular organisms.
Figure 1.1
• Prokaryotic
• Unicellular
• Cell walls contain peptidoglycan.
• Multiply by binary fission Eschericia coli
(rod shaped)
• 3 basic shapes, rods, cocci or spirals
• Bacteria -like prokaryotes are the
earliest living organisms Staphylococcus
aureus
(3.5 billion years ago) (cocci)
• For energy, use organic chemicals,
inorganic chemicals, or photosynthesis
Leptospira
•May cause disease. (spiral)
• Prokaryotic
•Lack peptidoglycan
•Do not cause disease
•Live in extreme environments
•Include
•Methanogens
•Extreme halophiles
•Extreme thermophiles
Figure 4.5b
• Eukaryotes
• Chitin cell walls
• Use organic chemicals for energy.
• Molds and mushrooms are Yeast Cells Budding
(reproducing)
multicellular
• Yeasts are unicellular
• Source of some antibiotics
• Decomposers
Penicillium (mold)
• May cause disease
• Unicellular eukaryotes
• Absorb or ingest organic chemicals
• May be motile via pseudopods,
cilia, or flagella
• May cause disease
Amoeba proteus streaming and
engulfing a paramecium
• Eukaryotes
•Cellulose cell walls
•Use photosynthesis for energy
•Produce molecular oxygen and
organic compounds
•Important food source for
other organisms
•Do not cause disease.
•Eukaryote
•Multicellular animals
•Parasitic flatworms and round worms are called
helminths.
• May cause disease
Figure 12.28a
• Acellular NOT CELLS !
• Genetic information RNA or DNA surrounded by a
protein coat). HIV
• Obligate internal parasites (require host cells to
reproduce).
• Submicroscopic .
H1N1
• Many cause disease.
Size of things
Microorganisms are the most dominant organisms on earth.
Most co-exist with (commensally) or are useful to humans.
Very small percentage are pathogenic to humans .
They were here before us!
Evolutionary Timeline
The impact of microorganisms on human affairs
Agriculture Energy/ Environment
• N2 Fixation (N2 2NH3) •Biofuels • Bioremediation • Mining (Cu)
Fermentation O2
• Nutrient Cycling- Carbon, Corn Ethanol (Spilled oil CO2)
Nitrogen and sulfur.
• Animal husbandry
Food
• Food preservation •Fermented • Food additives
(heat, cold, radiation, foods (Citric acid, yeast)
Cellulose broken down in
rumen of cattle and chemicals)
sheep
Biotechnology
Disease • Genetically modified organisms
• Identify new disease • Production of pharmeceuticals
• Treatment, cure and (insulin and other human proteins)
prevention. • Gene therapy for certain diseases
Microbes and Human Welfare
Microbial ecology
Bacteria recycle carbon, nutrients, 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.
UN 2.1
Modern Biotechnology and Genetic Engineering
Biotechnology, the use of microbes to produce foods and
chemicals, is centuries old.
Genetic engineering is a new technique for biotechnology.
Through genetic engineering, bacteria and fungi can
produce a variety of proteins including vaccines and
enzymes.
Modern Biotechnology and Genetic Engineering
(continued)
Missing or defective genes in human cells can be replaced
in gene therapy.
Genetically modified bacteria are used to protect crops
from insects and from freezing.
Microbes and Human Disease
Bacteria were once classified as plants giving rise to use
of the term flora for microbes.
This term has been replaced by microbiota.
Microbes normally present in and on the human body
are called normal microbiota.
Normal Microbiota
Normal microbiota prevent growth of pathogens.
Normal microbiota produce growth factors such as
folic acid and vitamin K.
Infectious Diseases
Resistance is the ability of the body to ward off disease.
Resistance factors include skin, stomach acid, and
antimicrobial chemicals.
When a pathogen overcomes the host’s resistance, disease
results.
Emerging infectious diseases (EID): New diseases and
diseases increasing in incidence.
Emerging Infectious Diseases
Escherichia coli O57:H7
Toxin-producing strain of E. coli
First seen in 1982
Leading cause of diarrhea worldwide
Emerging Infectious Diseases
Invasive group A Streptococcus
Rapidly growing bacteria that cause extensive
tissue damage
Increased incidence since 1995
Emerging Infectious Diseases
Swine Flu
Influenza A virus (H1N1)
Current epidemic occuring
Vaccine available
Emerging Infectious Diseases
Acquired immunodeficiency syndrome (AIDS)
Human immunodeficiency virus (HIV)
First identified in 1981
Worldwide epidemic infecting 44 million people; 14,000
new infections every day
Sexually transmitted disease affecting males and females
In the United States, HIV/AIDS cases: 30% are female and
75% are African American
Infectious Disease
A Brief History of Microbiology
Ancestors of bacteria were the first life on Earth.
The first microbes were observed in 1673.
The First Observations
In 1665, Robert Hooke reported that living things were
composed of little boxes or cells Cell Theory
Cell theory: All living things are composed of cells and
come from preexisting cells.
The First Observations
1673-1723, Leeuwenhoek
invented the first microscope
(1673)
achieved 300x magnification
observed bacteria and protozoa
(“animalcules”)
Figure 1.2b
The Debate Over Spontaneous
Generation
The hypothesis that living organisms arise from nonliving
matter is called spontaneous generation. According to
spontaneous generation, a “vital force” forms life.
The alternative hypothesis, that the living organisms arise
from preexisting life, is called biogenesis.
Evidence Pro and Con
1668: Francisco Redi filled six jars with decaying meat.
Conditions Results
Three jars covered with fine No maggots
net
Three open jars Maggots appeared
From where did the maggots come?
What was the purpose of the sealed jars?
Spontaneous generation or biogenesis?
Evidence Pro and Con
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?
Spontaneous generation or biogenesis?
Evidence Pro and Con
1765: Lazzaro Spallanzani boiled nutrient solutions
in flasks.
Conditions Results
Nutrient broth placed in flask, No microbial growth
heated, then sealed
Spontaneous generation or biogenesis?
Evidence Pro and Con
1861: Louis Pasteur demonstrated that microorganisms
are present in the air.
Conditions Results
Nutrient broth placed in flask, Microbial growth
heated, not sealed
Nutrient broth placed in flask, No microbial growth
heated, then sealed
Spontaneous generation or biogenesis?
The Theory of Biogenesis Proven
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.
Fermentation is the conversion of sugar to alcohol to
make beer and wine.
Microbial growth is also responsible for spoilage of food.
Bacteria that use alcohol and produce acetic acid spoil
wine by turning it to vinegar (acetic acid).
Fermentation and Pasteurization
Pasteur demonstrated that these
spoilage bacteria could be killed
by heat that was not hot enough
to evaporate the alcohol in wine.
Pasteruization is the application
of a high heat for a short time.
Figure 1.4 (1 of 3)
The Germ Theory of Disease
1860s: Joseph Lister used a chemical disinfectant to prevent surgical
wound infections after looking at Pasteur’s work showing microbes are in
the air, can spoil food, and cause animal diseases.
1876: Robert Koch proved that a bacterium causes anthrax and provided the
experimental steps, Koch’s postulates, to prove that a specific microbe
causes a specific disease Germ theory of disease.
Koch’s Postulates
1. Observe same organism in all diseased but no healthy individuals.
2. Isolate microbe in pure culture on artificial media.
3. Inoculate healthy host with pure culture and get the same disease.
4. Re-isolate the same organism from infected host.
Levels of Classification
Domain
Kingdom
Phylum
Class
Order
Family
Genus Binomial
System*
Species
* Binomial naming system - Genus species
example Escherichia coli or E. coli or
Escherichia coli.
• Linnaeus established the system of scientific
nomenclature.
• Each organism has two names: the genus and
specific (species) epithet (name).
• Are italicized or underlined. The genus is capitalized and
the specific epithet is lower case.
•Are “Latinized” and used worldwide.
•May be descriptive or honor a scientist.
•Staphylococcus aureus
Describes the clustered arrangement of the cells (staphylo-)
and the golden color of the colonies
(aur-).
Escherichia coli (E. coli)
Honors the discoverer, Theodor Escherich, and
describes the bacterium’s habitat–the large intestine
or colon.