Archaebacteria & Eubacteria

Archaebacteria: the oldest living organisms on Earth
Three phyla - methanogens, extreme halophiles, thermoacidophiles

-Body plan – prokaryotic and unicellular
-Found in very harsh, extreme conditions (bottom of sea, volcanic vents)
            -the very beginning of evolution
            -only survivor of early Earth’s atmosphere that had little oxygen
            -no previous event led to the evolution of the kingdom
-Metabolism – mostly autotrophic
            -capable of self-nourishing by converting inorganic materials to nutrients
-Digestion – doesn't have a digestive system
-Circulation – no heart
-Respiration – obtain energy from carbon dioxide, oxygen, and sun
-Nervous – no brain
-Reproduction – asexual
            -binary fission – bacterial DNA replicates, pinches off at center, divides into two- each with a copy of the DNA
            -quick, some species divide once every 20 minutes

Phylum: Methanogen
-Live in environments without oxygen
            -swamps, deep-sea waters, sewage facilities, stomachs of cows (hence, why they produce methane as a waste product)
-Obtain energy from carbon dioxide and hydrogen gas
-Example: Methanosarcina barkeri

Phylum: Extreme halophiles
-“Salt loving”
-Live in areas with high salt concentration
            -Dead Sea, Great Salt Lake
-Cannot tolerate unsalty environments
-Bacteriorhodopsin – sunlight as a source of photosynthetic energy
Example: Halobacterium- Halococcus

Phylum: Extreme Thermoacidophiles
-“Heat and acid loving”
-Live in hot, acidic waters
            -sulfur springs or deep-sea thermal vents
            -temps of 160 degrees Fahrenheit or higher
            -pH levels of 1 or 2 (concentrated sulfuric acid)
-Example: Picrophilus torridus

Eubacteria: the common bacteria
More complex and common than Archaebacteria
Four phyla - cyanobacteria, spirochetes, proteobacteria, and gram-positive bacteria
-Found everywhere around us (body, food, etc.)
-Classification – gram staining

            -using 4 liquids: crystal violet, iodine, safranin, alcohol wash
            -purple (crystal violet): gram-positive – thick layer of peptidoglycan, but susceptible to antibiotics
            -pink (safranin): gram-negative – thick lipid bilayer makes it selectively permeable and not as susceptible to antibiotics
-3 general shapes: bacilli, cocci, and spirilla
            -bacilli – oblong and thick
            -cocci – round
            -spirilla - spiral

-Body Plan – prokaryotic, mostly unicellular
-Divergent event - when little amounts of oxygen started appearing in the Earth's atmosphere, eubacteria started evolving from the extreme archaebacteria
            -Some of these bacteria used the oxygen that the archaebacteria expelled as a waste product
-Metabolism – autotrophic and heterotrophic, lithotrophic (inorganic electron donors), organotrophic (organic compounds as electron donors), chemotrophic (energy conservation)
            -Example Autotroph: phototrophic cyanobacteria
            -Example Heterotroph: pseudomona
-Digestion – doesn’t have a digestive system
-Circulation – no heart
-Respiration – use oxygen and chemicals to obtain energy
-Nervous system – no brain
-Reproduction – asexual
            -binary fission, formation of identical bacterial cells

Phylum: Cyanobacteria
-Use sun’s energy to make food
-Give off oxygen as byproduct
            -allow aerobic organisms to survive
-Found in water, once thought to be blue-green algae
-Certain cyanobacteria grow in chains that sometimes form heterocysts
            -heterocyst - specialized cells that contain enzymes that fix atmospheric nitrogen
-Causes eutrophication - sudden increase of cyanobacteria due to a high availability of nutrients
-Example: Prochlorococcus

Phylum: Spirochetes
-Gram-negative, spiral-shaped, and heterotrophic
-Some live with oxygen (aerobic), others do not (anaerobic)
-Some are parasitic, some are free-living
-Treponema pallidum causes syphilis
-Example: Borrelia burgdorferi (causes Lyme Disease)

Phylum: Gram-Positive Bacteria
-Produces yogurt by growing and fermenting in milk (produces lactic acid)
-Produces antibiotics
-Found in oral cavity and intestinal tract where they retard the growth of disease-causing bacteria
-Lactobacilli releases acid to stop tooth decay
-Example: Streptococcus (causes Strep throat)

Phylum: Proteobacteria
-Largest phylum - divided into three groups
1. Enteric bacteria
            -gram-negative, heterotrophic bacteria found in the intestinal tracts of animals
            -aerobic or anaerobic
            -produces vitamins and enzymes that help break down food
Example: Escherichia coli - produces vitamin K and assists enzymes in breaking down food

2. Chemoautotrophs
            -gram-negative bacteria that extracts energy and breaks down minerals
3. Nitrogen-fixing bacteria
            -fix nitrogen, usually found in symbiotic relation with the roots of plants

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