Download Bacterial Classification

Bacterial Classification
•  DOMAINS:
•  Bacteria
•  Archaea
•  KINGDOM:
•  Monera (in five-kingdom system)
We will focus our initial attempts at
classification on Bergey’s Manual of
DETERMINATIVE Bacteriology
•  It uses the following characteristics in attempting to
classify bacteria:
•  Gram stain reaction (cell wall type)
•  Cellular morphology (rod, coccus, etc.)
•  Oxygen requirements (obligate anaerobe, etc.)
•  Nutritional patterns (chemoautotrophs, etc.)
•  Remember, the SYSTEMATIC Manual is
attempting to base this entire scheme on phylogeny.
Four Divisions (same as Phyla)
•  Gram-negative
•  Gram-positive
•  Mycoplasmas - have no cell wall!
•  Archaebacteria - have strange cell walls
w/no peptidoglycan.
DIVISION I: GRAM
NEGATIVE BACTERIA
•  The Cyanobacteria:
aerobic photosynthesizers – primary producers in aquatic ecosystems
Representative genus: Oscillatoria
Gram Negative cont’d - spirals
–  The Spirochetes:
•  spiral in shape, possess axial filament
Representative genera:
– Treponema - causes syphilis
– Borrelia - causes Lyme Disease
–  Other “spiral” bacteria •  Helicobacter - causes stomach ulcers
–  microaerophilic, spiral shaped, motile flagellum
•  Vibrio - causes cholera
–  facultatively anaerobic, “curved”, motile flagellum
Gram Negative cont’d - Enterics
–  The Enteric Bacteria:
•  facultatively anaerobic rods, often inhabit colon
Representative genera:
–  Escherichia (coli) - large part of the normal microbiota, can cause
food poisoning, used in research
–  Salmonella - causes food poisoning and typhoid fever
–  Shigella - causes dysentery
–  Klebsiella - member of normal microbiota in colon, may
cause bacterial pneumonia
–  Serratia - may cause nosocomial infections –  Yersinia - causes Plague (Black Death)
Gram Negative cont’d
•  Chlamydias and Rickettsias: (Obligate Parasites)
Chlamydia - causes a common sexually transmitted
disease (STD)
Rickettsia - causes Rocky Mountain Spotted Fever
•  Chemoautotrophs: –  usually oxidize reduced Sulfur, Iron, and Nitrogen
Compounds, live in muddy sediments, Thiobacillus - various species can oxidize reduced sulfur
or iron compounds
Gram Negative cont’d
– Aerobic Rods and Cocci
– Pseudomonas ubiquitous, lives in soil and water,
may cause food spoilage, opportunistic infections
– Neisseria causes gonorrhea, it is a diplococcus
– Bordetella causes Whooping Cough
– Rhizobium fixes atmospheric Nitrogen for plants
DIVISION II: GRAM POSITIVE
BACTERIA
•  Cocci
–  Staphylococcus: •  Cocci arranged in grapelike clusters
•  May cause food poisoning, wound infections, boils, toxic shock
syndrome
–  Streptococcus: •  Cocci arranged linear chains
May cause sore throat and Scarlet Fever
Gram positive cont’d
Rods
–  Endospore-forming rods
Representative genera:
–  Bacillus - causes anthrax
–  Clostridium - causes botulism and tetanus
–  Acid-fast, non-spore forming rods
Representative genus:
–  Mycobacterium - causes tuberculosis and leprosy
Gram positive cont’d
•  The Actinomycetes:
– filamentous (looks like fungal type growth),
most live in soil
Representative genus: Streptomyces produces many antibiotics including
streptomycin.
DIVISION III: The Mycoplasmas BACTERIA LACKING A CELL
WALL
Representative genus: Mycoplasma - may cause
bacterial pneumonia
DIVISION IV: THE
ARCHAEBACTERIA
•  Have unusual cell walls, no peptidoglycan
–  Extreme Halophiles: “salt-lovers”
•  Halobacterium - photosynthesizes using bacteriorhodopsin, requires high
salt concentrations
–  Extreme Thermophiles: “ heat-lovers”
•  Sulfolobus, Thermococcus - thrive at temperatures from 70oC to over 100oC,
live in deep sea vents, volcanoes, hot springs
–  Thermoacidophiles: “heat and acid lovers”
•  Thermoplasma - thrives at pH ~ 2, 60 degrees C
–  Methanogens: “CH4 producers”
•  Methanobacterium - turn organic wastes, carbon dioxide, and hydrogen gas
into methane; used in sewage treatment plants