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The Microbial World and You
The Microbial World and You
Microorganisms
too small to be seen with unaided eye
“Germ”
rapidly growing cell
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What are microbes?
Fungi (molds, yeasts)
mycology
Protozoa
parasitology
Microscopic algae
phycology
What do they do?
Decompose
organic waste
Producers in the ecosystem
by photosynthesis
Produce industrial chemicals
Ethanol and acetone
Produce fermented foods
vinegar, cheese, and bread
Produce manufacturing products
(e.g., cellulase) and treatment (e.g., insulin)
A few are pathogenic,
 disease-causing
The better question might be, “what don’t they do?”
Allows humans to
Prevent food spoilage
Prevent disease occurrence
Led to aseptic techniques to prevent contamination in medicine and in microbiology
laboratories
Did you know?
Bacteria causes body odor
Bacteria, tiny as they are, can get sick, too!
Under the right conditions a bacterium like Escherichia coli can grow from just one cell to 1
million cells in less than 7 hours!
How their size compares?
How are microbes named and classified?
Linnaeus established
system of scientific nomenclature.
Each organism has two names:
genus and specific epithet.
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.
Scientific Names
Staphylococcus aureus
Describes the clustered arrangement of the cells (staphylo-) and the golden color of the
colonies
(aur-).
Escherichia coli
Honors the discoverer, Theodor Escherich, and describes the bacterium’s habitat–the
large intestine or colon
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Taxonomy
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What is systematics?
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Study of phylogenetic relationships

Also a way of organizing/ classifying
Phylogenetics = ________
Taxonomy = __________

Taxa (taxon—singular)
Look at the background!
Plant and Animal Kingdoms
Bacteria and fungi
put in the Plant Kingdom
Kingdom Protista proposed
 for bacteria, protozoa, algae, and fungi
Prokaryote introduced for cells "without a nucleus“
Prokaryote defined as cells in which nucleoplasm is
not surrounded by a nuclear membrane
Kingdom Fungi
Kingdom Prokaryotae proposed
Two types of prokaryotic cells found
How are prokaryotes classified?
Use Bergey’s Manual of Systemic Bacteriology
Divides prokaryotes into (based on rRNA sequences)
Bacteria
Archaea
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Who is Carl Woese?
1978: created current classification scheme
Three domains
Bacteria
Archaea
Eukarya
Protists
Fungi
Plants
Animals
What are the key differences between the three divisions?
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What is the taxonomy of organisms?
Domain
Kingdom
Phylum
Class
Order
Family
Genus
Species
How are eukaryotes classified?
Endosymbiotic theory
Numerous kingdoms, including
Protista
Fungi
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Plantae
Animalia
What about viruses—How are they classified?
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Not included in three domains, which are _______ _______ and ______
Why not?
Viral species: population of viruses with similar characteristics
How do I tell prokaryotes apart?
Really difficult
Morphology is very similar!
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So how can we tell them apart?
Lab techniques such as
Staining
Gram positive vs. Gram negative
So how can we tell them apart?
Biochemical test
Different bacteria will grow on different types of media
Serology
Carbohydrates
Proteins
Slide agglutination test
Look for clumping of bacteria with antiserum
Serotypes are strains with different antigens
DNA fingerprinting
rRNA sequencing
A closer look at the microbes
What are bacteria?
Simple, single-celled
ubiquitous
Prokaryotes
DNA is not inside a membrane
Come in different shapes
Coccus (cocci, plural)
Bacillus (bacilli, plural)
Spiral (corkscrew, comma or curved)
Peptidoglycan cell wall
Binary fission
Some have flagella
What are archaea?
Also prokaryotes
Cells wall do not have peptidoglycan
Live in extreme conditions
Extreme halophiles
Hyperthermophiles
Methanogens
Not pathogenic
What are fungi?
Eukaryotes
Have a true nucleus
More closely related to __________
wall of chitin
Uni- and multicellular
Includes
Molds
Mushrooms
Yeasts
Slime molds
Sexual and asexual reproduction
What are protozoa?
Eukaryotes
Absorb or ingest
organic chemicals
May be motile via pseudopods, cilia,
or flagella
What are algae?
Eukaryotes
Cellulose cell walls
Use photosynthesis for energy
Produce molecular oxygen and organic compounds
What are viruses?
Acellular
Consist of DNA or RNA core
Core is surrounded by a protein coat.
Coat may be enclosed in a lipid envelope.
Viruses are replicated only when they are in a living host cell.
What are multicellular animal parasites?
Eukaryote
Multicellular animals
Parasitic flatworms and round worms are called helminths.
Microscopic stages in life cycles.
Brief History of Microbiology
The First Observations
Ancestors of bacteria were
first life on Earth.
observed in 1673.
1665, Robert Hooke reported
living things were composed of little boxes or cells.
1858, Rudolf Virchow
cells arise from preexisting cells.
Cell theory: All living things are composed of cells and come from preexisting cells.
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How did we discover microbes?
Before the microscope:
Spontaneous generation
“vital force” forms life.
Microscope
Van Leeuwenhoeke, 1670s
Louis Pasteur, 1861
Showed microorganisms are in the air
Refutes spontaneous generation with biogenesis
Used curved flask
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When was the golden age of microbiology?
1857-1914
Pasteurization
Developed after investigation of fermentation
Demonstration of aseptic technique
microbes are responsible for fermentation.
Fermentation
conversion of sugar to alcohol to make beer and wine.
Microbial growth
responsible for spoilage of food.
Pasteur demonstrated
spoilage bacteria killed by heat
Pasteruization
high heat for a short time.
The Germ Theory of Disease
Joseph Lister, 1860s used a chemical disinfectant to prevent surgical wound infections
Germ theory of disease
Robert Koch, 1876, Germany
Bacillus anthracis causes anthrax
provided the experimental steps
Vaccination
Edward Jenner, 1796
Small pox and cow pox
Immunology
What about modern microbiology?
1928: Alexander Fleming
first antibiotic.
Penicillium fungus made
antibiotic, penicillin, that killed S. aureus.
1940s: Penicillin was tested clinically and mass produced.
Some terms in microbiology
Bacteriology is the study of bacteria.
Mycology is the study of fungi.
Parasitology is the study of protozoa and parasitic worms.
Immunology is the study of immunity. Vaccines and interferons are being investigated to
prevent and cure viral diseases
Virology is the study of viruses.
Some modern concepts
Bioremediation
degrade organic matter in sewage.
 degrade or detoxify pollutants such as oil and mercury.
Biological Insecticides
Biotechnology
Genetic engineering
What is normal microbiota?
Normal microbiota prevent growth of pathogens.
Normal microbiota produce growth factors such as folic acid and vitamin K.
Resistance is the ability of the body to ward off disease.
Resistance factors include skin, stomach acid, and antimicrobial chemicals.
What are infectious diseases?
When a pathogen overcomes the host’s resistance, disease results.
Emerging infectious diseases (EID): New diseases and diseases increasing in incidence.
West Nile Virus
Bovine spongiform encephalopathy
Ebola hemorrhagic fever
Hantavirus
AIDS
Anthrax