Download B. Class Cyanobacteriae—The Blue

Chapter 17
Kingdom Monera and Viruses
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. Fossils of eukaryotic cells
are 1.5 billion years old
C. Number of Species
1. About 5,000 species known
2. Occur in almost any natural habitat
3. Some species may have many different strains (Streptomyces
pneumonia has 84 strains
D. Pathogenic or Harmless?
• more than 90% either harmless or beneficial to humans
II. Features of the Kingdom Monera
A. Prokaryotic Cells
B. Colonies or Filaments
C. Motility
1. Most nonmotile
2. Some possess bacterial flagella
3. Others move by gliding motion
D. Nutrition
1. Absorption of food in solution
2. Chemosynthesis i.e. obtain their energy through chemical
reactions involving various compounds or elements
3. A few bacteria such as cyanobacteria and chloroxybacteria
carry on a form of photosynthesis
E. Reproduction
1. Predominantly asexual by binary fission
2. Genetic recombination in several groups through the use of pili
(minute tubes that allow the passage of the bacterial chromosome
from the donor cell to the recipient cell
III. Cellular Detail and Reproduction
A. Cell Structure
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
B. Reproduction
1. By binary fission
• a bacterium may undergo fission every 10-20 minutes
2. Conjugation
• part of a chromosome is transferred from donor cell to
recipient through pilus
3. Transformation
• living cell picks up fragments of DNA released by dead
cells
4. Transduction
• fragments of DNA carried from one cell to another by
viruses
IV. Size, Form, and Classification of Bacteria
A. Size
• most are less than 2-3 µm in diameter, the smallest being
around 0.15 µm
B. Form
1. Cocci
• spherical
2. Bacilli
• rod-shaped or cylindrical
3. Spirilli
• helical or spiral
C. Classification
1. Based on reaction to a dye
2. Two categories
a. Gram-positive
b. Gram-negative
3. Stain named after Christian Gram
• made observation in 1884
V. Subkingdom Archaebacteriobionta: 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 Sulpholobus Bacteria
• occur in sulphur hot springs
E. Human Relevance of the Archaebacteria
• methane production for fuel
VI. Subkingdom Eubacteriobionta: The True Bacteria (Division
Eubacteriophyta)
A. Class Eubacteriae—The Unpigmented, Purple, and Green
Sulphur 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, sulphur, and hydrogen bacteria
3. Human relevance of the Unpigmented, Purple, and Green
Sulphur Bacteria
a. Compost and composting
b. True bacteria and disease
1) Modes of access of disease bacteria
a) Access from the air ("strep throat", chlamydias)
b) Access through contamination of food and drink
i) Salmonella food poisoning
ii) Staphylococcus food poisoning
iii) Legionnaire's disease
iv) Botulism
c) Access through direct contact
- Syphilis and Gonorrhea, Anthrax, Brucellosis
d) Access through wounds
- Tetanus, Gas gangrene
e) Access through bites of insects and other organisms
i) Bubonic plague (the "Black Death")
ii) Tularemia
iii) Rickettsias
iv) Pleuropneumonia-like organisms (PPLOs)
v) Lyme disease
2) Koch's postulates
a) Microorganism must be present in all cases of the
disease
b) Microorganism must be isolated from the victim in
pure culture
c) Microorganism from pure culture, when injected into
susceptible host, must produce the disease in the host
d) Microorganism must be isolated from the
experimentally infected host and grown in pure
culture
c. True bacteria useful to humans
1) Biological controls
a) Bacillus thuringiensis (control of caterpillars)
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
d. Other useful bacteria
1) Research into chemistry of vision
2) Dairy industry
3) Digestive system aids (Lactobacillus acidophilus)
4) Production of metabolic wastes with industrial use
5) Food production
B. Class Cyanobacteriae—The Blue-Green Bacteria
1. Introduction
a. Pigments
1) Chlorophyll a
2) Phycocyanin
3) Phycoerythrin
b. Can both fix nitrogen and produce oxygen
2. Distribution
a. Widely distributed in fresh and marine waters
b. Some precipitate carbonate deposits (travertine)
3. Form, metabolism, and reproduction
a. Form
1) Cells often occur in chains or hair-like filaments
2) Some species occur as colonies
3) Color varies depending on pigments present, although
half are blue-green
b. Metabolism
• store carbohydrates, lipids, and the nitrogenous
cyanophycin
c. Reproduction
1) New cells formed by fission
2) New colonies may be formed by fragmentation at:
a) Heterocysts (nitrogen-fixing cells)
b) Akinetes
3) Genetic recombination
4. Blue-green bacteria, chloroplasts, and oxygen
a. Symbiotic origin of chloroplasts from blue-green bacteria
• blue-green bacteria occur symbiotically and function
essentially as chloroplasts in host organism
b. Speculation that chloroplasts originated as
prochlorobacteria
5. Human relevance of the blue-green bacteria
a. Occur at bottom of food chains
b. Production of blooms
c. Poisons
d. Spirulina used as food
e. Undesirable effects in human water supplies
f. Nitrogen fixation
C. Class Prochlorobacteriae—The Prochlorobacteria
1. Discovered living on sea squirts (1976)
2. Have chlorophylls a and b, but not phycobilins
3. Thylakoid membranes double, unlike thylakoids of bluegreen bacteria
4. One very abundant form found at depth of 100 m in ocean
waters
VII. 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
4. Viroids and Prions