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Review. Remember from earlier this year that there are two broad categories of organisms: *Prokaryotes – have No membrane bound organelle *Eukaryotes – have membrane bound organelle. Important Features. -all are prokaryotes -all have plasmids (small circular packages of DNA)

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Remember from earlier this year that there

are two broad categories of organisms:

*Prokaryotes – have No membrane bound organelle

*Eukaryotes – have membrane bound organelle

important features
Important Features

-all are prokaryotes

-all have plasmids (small circular packages of DNA)

-most have peptidoglycan in their cell walls

-flagella are made with a globular protein called flagellin- no 9+2 arrangement




(Small chunks of food)

locomotion methods of movement
Locomotion (Methods of Movement)
  • Bacterial Flagellum- lacks microtubules
  • Pili- short, thin appendages

E. coli

E. coli

  • Autotrophs- manufacture organic compounds
    • Photoautotrophs- use light energy & CO2
    • Chemoautotrophs-use inorganic substances like H2S, NH3, and other nitrogen compounds
  • Heterotrophs- obtain energy by consuming organic compounds
    • parasites- get energy from living organisms
    • saprobes (saprophytes)- get energy from dead, decaying matter; also called decomposers
oxygen preferences
Oxygen Preferences
  • obligate aerobes must have oxygen
  • obligate anaerobes cannot live in oxygen
  • facultative anaerobes can grow with or without oxygen
2 bacteria kingdoms
2 Bacteria Kingdoms
  • Kingdom Archaebacteria - are ancient bacteria that live in extreme environments
  • Kingdom Eubacteria - are generally referred to as bacteria or germs, and are considered more recent. Most types of bacteria belong in this kingdom.
  • First appeared approximately 3.7 BYA
the archaebacteria
The Archaebacteria:
  • do not have peptidoglycan in their cell walls
  • have ribosomes similar to eukaryotes
  • have unique lipids in their plasma (cell) membranes
the archaebacteria also
The Archaebacteria also:
  • have some genes that resemble eukaryotic genes
  • usually are not pathogenic (they don’t usually make us sick!)
  • live in extreme environments:
    • high concentrations of salt
    • extremes of pH and temperature
3 archaebacterial groups
3 Archaebacterial Groups
  • Methanogens
  • Halophiles
  • Thermoacidophiles = live in extremely hot, acid environments
  • anaerobic bacteria that get energy by turning H2 and CO2 into methane (CH4)
  • live in mud, swamps, and the guts of cows, humans, termites and other animals
  • are organisms that live in environments with extremely high salt concentrations
    • some extreme halophiles can live in solutions of 35 % salt. (seawater is only 3% salt!)
  • halophile means “salt loving”
  • most halophiles are aerobic and heterotrophic; others are anaerobic and photosynthetic, containing the pigment bacteriorhodopsin
diversity of halophilic organisms
Diversity of Halophilic Organisms
  • halophiles are found in salt lakes, salt marshes, subterranean salt deposits, dry soils, salted meats, hypersaline seas, and salt evaporation pools
  • the Red Sea was named after the halobacterium that turns the water red during massive blooms.



solar salterns

Owens Lake,

Great Salt Lake,

coastal splash zones,

Dead Sea

  • Like temperature and pH extremes
    • Hot = up to 110ºC
    • Cold = down to 1ºC
    • Acid = as low as pH 2
    • Alkali = as high as pH 9
  • they are chemoautotrophs, using H2S
  • the first Extremophile was found about 30 years ago
extreme temperatures
Extreme Temperatures
  • Thermophiles - High temperature = 60-800C
    • Thermal vents and hot springs
    • May go hand in hand with chemical extremes
  • Psychrophiles - Low temperature
    • Arctic and Antarctic
      • 1/2 of Earth’s surface is oceans between 10C & 40C
      • Deep sea –10C to 40C
      • Most rely on photosynthesis



Hydrothermal Vents in the ocean, and

Obsidian Pool in Yellowstone National Park


Alan Hills Ice Field: Antarctica

Psychrophile Environments

thermophile applications
Thermophile Applications
  • many industrial processes involve temperature extremes, which is a problem for most enzymes
    • Enzymes to work on foods that need to be refrigerated
    • Perfumes - most don’t tolerate high temperatures
    • Cold-wash detergents
    • PCR reactions
chemical extremes
Chemical Extremes
  • Acidophiles - Acidic
    • Again thermal vents and some hot springs
  • Alkaliphiles - Alkaline
    • Soda lakes in Africa and western U.S.
  • Halophiles - Highly Salty
    • Natural salt lakes and manmade pools
    • Sometimes occurs with extreme alkalinity

Life at High Temperatures, Thomas M. Brock

  • Enzymes used to increase efficiency of animal feeds
    • enzymes help animals extract nutrients from feed
      • more efficient and less expensive
  • “Stonewashed” pants
    • Alkaliphilic enzymes soften fabric and release some of the dyes, giving worn look and feel
  • Detergents
    • Enzymes to dissolve proteins or fats
    • Alkaliphilic enzymes can work with detergents

Alkaliphile Environments

e.g. Mono Lake alkaline soda lake, pH 9, salinity 8%

examples of unusual habitats
Examples of Unusual Habitats
  • The bacterium pseudomonas was found living on a desert plant in the Negev Desert. The plant secretes salt through salt glands on its leaves.
  • Bacillus was found in the nasal cavities of desert iguanas. These iguanas have salt glands in their nasal cavities that secrete KCl brine during osmotic stress.
special techniques for survival
Special Techniques for Survival

While external environments are “extreme”, internal cell environments are “normal”.

  • Ways to protect the cell:
    • Acidophiles and Alkaliphiles sometimes excrete protective substances and enzymes
    • Acidophiles often lack cell wall
    • Some moderate halophiles have high concentrations of a solute inside to avoid “pickling”
  • Many microbes contain unusual enzymes
interesting facts
Interesting Facts
  • The term “red herring” comes from the foul smell of salted meats that were spoiled by halobacterium.
  • There have been considerable problems with halophiles colonizing leather during the salt curing process.
future applications
Future Applications

Many possible applications using halophiles are being explored such as:

  • genetically engineering halophilic enzymes, encoding DNA into crops to allow for salt tolerance
  • treatment of waste water
  • Now you know something about Extremophiles
    • where they live
    • how they survive
  • They are interesting because
    • they have enzymes that work in unusual conditions