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Chapter 14 : Domain (Kingdom) Bacteria, Domain (Kingdom) Archaea,
and Viruses
Overview
The chapter introduces Kingdom Bacteria with an overview of its features, and describes the
luminescent bacteria associated with flashlight fish as an introduction to bacteria. A brief
investigation of the abundance and features of bacteria and their reproduction is followed by
a discussion of the Kingdom Archaea, or archaebacteria and true bacteria (Kingdom
Bacteria). Representatives and human relevance of heterotrophic and autotrophic bacteria
are surveyed, followed by sections on composting, disease transmission, bacterial diseases,
and Koch's Postulates.. The text discusses antibiotic resistant strains of tuberculosis and
several strains of E. coli that have been involved in human illness. Blue-green bacteria and
prochlorobacteria are explored next, and the human relevance of blue-green bacteria is
examined. The chapter concludes with an overview of the nature, reproduction, and human
relevance of viruses.
Detailed Lecture Outline
I.
Introduction to the Bacteria
A. Symbiotic Relationships
• mutualism between luminescent bacteria and flash-light fish
B. Ancient Organisms
• known as fossils 3.5 billion years old
C. Prevalence of Species
1. About 10 million to 1 billion species estimated
• difficult to relate DNA sequences to functional differences
2. Occur in almost any natural habitat
3. Some species may have many different strains
D. Pathogenic or Harmless?
• more than 90% either harmless or beneficial to humans
II. Features of Kingdoms Bacteria and Archaea
A. Cellular Detail and Reproduction of Bacteria
1. Prokaryotic
• no membrane-bound organelles
2. Nucleoid
• single chromosome (long, very condensed DNA molecule in ring form)
3. Plasmids
• small, circular, extrachromosomal DNA molecules
4. Microcompartments
5. Reproduction
a. By binary fission
• a bacterium may undergo fission every 10-20 minutes
b. Conjugation
• part of a chromosome is transferred from donor cell to recipient through
pilus
c. Transformation
• living cell picks up fragments of DNA released by dead cells
d. Transduction
• fragments of DNA carried from one cell to another by viruses
B. Size, Form, and Classification of Bacteria
1. Size
• most are less than 2-3 µm in diameter, the smallest being around 0.15 µm
2. Form
a. Cocci
• spherical
b. Bacilli
• rod-shaped or cylindrical
c. Spirilli
• helical or spiral
3. Classification
a. Based on reaction to a dye
b. Two categories
a. Gram-positive
b. Gram-negative
c. Stain named after Christian Gram
• made observation in 1884
4. Social Life
a. biofilms
b. quorum sensing
III. Domain Bacteria (Kingdom Bacteria)—The True Bacteria (Phylum Bacteriophyta)
A. Class Bacteriae—The Unpigmented, Purple, and Green Sulfur Bacteria
1. Heterotrophic bacteria
a. Saprobes
b. Parasites
2. Autotrophic bacteria
a. Photosynthetic bacteria
1) Some produce oxygen, others sulphur
2) Pigments located in thylakoids
• bacteriochlorophyll or chlorobium chlorophyll
b. Chemoautotrophic bacteria
1) Obtain energy through oxidation of reduced inorganic groups (NH3,
H2S)
2) Examples: iron, sulfur, and hydrogen bacteria
IV. Human Relevance of the Unpigmented, Purple, and Green Sulfur Bacteria
A. Composting and Compost
B. True Bacteria and Disease
1. Modes of access of disease bacteria
a. Access from the air ("strep throat", chlamydias)
 drug resistant strains of tuberculosis
b. Access through contamination of food and drink
1) Salmonella food poisoning
2) Staphylococcus food poisoning
3) E. coli contaminated food and water
4) Clostridium difficile
• Common in hospitals, elderly and long term care facilities due to
antibiotic treatments
5) Legionnaire's disease
6) Botulism
•infant botulism
c. Access through direct contact
1) Syphilis. Gonorrhea and Chlamydia
2) Anthrax
3) Brucellosis
d. Access through wounds
1) Tetanus
2) Gas gangrene
e. Access through bites of insects and other organisms
1) Bubonic plague (the "Black Death")
2) Tularemia
3) Rickettsias
4) Pleuropneumonia-like organisms (PPLOs)
5) Lyme disease
C. Koch's Postulates
1. Microorganism must be present in all cases of the disease
2. Microorganism must be isolated from the victim in pure culture
3. Microorganism from pure culture, when injected into susceptible host, must
produce the disease in the host
4. Microorganism must be isolated from the experimentally infected host and
grown in pure culture
D. True Bacteria Useful to Humans
1. Bacillus thuringiensis and Bacillus popilliae
a. Bacillus thuringiensis
• control of caterpillars, cutworms and genetic engineering
b. Bacillus thuringiensis (var. israelensis)
• control of mosquitoes
c. Bacillus popilliae
• control of Japanese beetle grubs
2. Bioremediation
a. Break down of nitroglycerin and trinitrotoluene
b. Pseudomonas capacia
• breakdown of oil spills and chemical dumps
3. Other Useful Bacteria
a. Research into chemistry of vision
b. Dairy industry
c. Digestive system aids (Lactobacillus acidophilus)
d. Production of metabolic wastes with industrial use
e. Food production
V. Class Cyanobacteriae—The Cyanobacteria (Blue-Green Bacteria)
A. Introduction
1. Pigments
a. Chlorophyll a
b. Phycocyanin
c. Phycoerythrin
2. Can both fix nitrogen and produce oxygen
B. Distribution
1. Widely distributed in fresh and marine waters
2. Some precipitate carbonate deposits (travertine)
C. Form, Metabolism, and Reproduction
1. Form
a. Cells often occur in chains or hair-like filaments
b. Some species occur as colonies
c. Color varies depending on pigments present, although half are
blue-green
2. Metabolism
• store carbohydrates, lipids, and the nitrogenous cyanophycin
3. Reproduction
a. New cells formed by fission
b. New colonies may be formed by fragmentation at:
1) Heterocysts (nitrogen-fixing cells)
2) Akinetes
c. Genetic recombination
D. Cyanobacteria, Chloroplasts, and Oxygen
1. Symbiotic origin of chloroplasts from blue-green bacteria
• blue-green bacteria occur symbiotically and function essentially as
chloroplasts in host organism
2. Speculation that chloroplasts originated as prochlorobacteria
E. Human Relevance of the Cyanobacteria (Blue-Green Bacteria)
1. Occur at bottom of food chains
2. Production of blooms
3. Poisons
4. Spirulina used as food
5. Undesirable effects in human water supplies
6. Nitrogen fixation
VI. Class Prochlorobacteriae—The Prochlorobacteria
A. Discovery
• Discovered living on sea squirts (1976)
B. Characteristics
1. Have chlorophylls a and b, but not phycobilins
2. Thylakoid membranes double, unlike thylakoids of blue-green bacteria
3. One very abundant form found at depth of 100 m in ocean waters
VII. Kingdom Archaea (Domain Archaea)—The Archaebacteria
A. Distinctive Characteristics
1. Unique sequence of bases in RNA
2. Cell walls lack muramic acid
3. Production of distinctive lipids
B. The Methane Bacteria
1. Anaerobic
2. Produce methane from carbon dioxide and hydrogen
C. The Salt Bacteria
1. Thrive in high salinity
2. Carry on photosynthesis with the aid of bacterial rhodopsin
D. The Sulfolobus Bacteria
• occur in sulphur hot springs
E. Human Relevance of the Archaebacteria
• methane production for fuel
VIII. Viruses
A. Introduction
1. Smallpox
a. An often fatal, communicable disease
b. Has now been eradicated
2. Vaccination against smallpox
• performed by Edward Jenner, a country physician, in 1796
B. Size and Structure
1. Vary in diameter from 15 to 300 nm
2. Consist of nucleic acid core surrounded by a protein coat
a. Nucleic acid may be DNA or RNA, but never both
b. Protein coat often has 20 sides, resembling tiny geodesic domes
C. Bacteriophages
• viruses that attack bacteria
D. Viral Reproduction
1. Viruses replicate only at the expense of their host cells
2. Viruses must become attached to a susceptible cell
3. Once inside the host cell, their DNA or RNA directs the synthesis of new viral
particles
4. Some viruses mutate rapidly
5. Viruses may affect the metabolism of their host cells
6. Infected cells can produce interferon which protects uninfected cells
E. Human Relevance of Viruses
1. Numerous diseases caused by viruses
2. AIDS, caused by a retrovirus called HIV
3. Production of vaccines
IX. Viroids and Prions