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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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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


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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


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Cytosol

Granules

(Small chunks of food)


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Locomotion (Methods of Movement)

  • Bacterial Flagellum- lacks microtubules

  • Pili- short, thin appendages


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Bacteria

E. coli

E. coli


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Nutrition

  • 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


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Oxygen Preferences

  • obligate aerobes must have oxygen

  • obligate anaerobes cannot live in oxygen

  • facultative anaerobes can grow with or without oxygen


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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


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The Archaebacteria:

  • do not have peptidoglycan in their cell walls

  • have ribosomes similar to eukaryotes

  • have unique lipids in their plasma (cell) membranes


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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


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3 Archaebacterial Groups

  • Methanogens

  • Halophiles

  • Thermoacidophiles = live in extremely hot, acid environments


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Methanogens

  • 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


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Halophiles

  • 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


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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.


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Halophile

Environments

solar salterns

Owens Lake,

Great Salt Lake,

coastal splash zones,

Dead Sea


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Thermoacidophiles

  • 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


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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


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Thermophile

Environments

Hydrothermal Vents in the ocean, and

Obsidian Pool in Yellowstone National Park


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Alan Hills Ice Field: Antarctica

Psychrophile Environments


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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


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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


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Life at High Temperatures, Thomas M. Brock

Acidophiles

  • Enzymes used to increase efficiency of animal feeds

    • enzymes help animals extract nutrients from feed

      • more efficient and less expensive



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Alkaliphiles

  • “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


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Alkaliphile Environments

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


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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.


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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


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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.


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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


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Summary

  • Now you know something about Extremophiles

    • where they live

    • how they survive

  • They are interesting because

    • they have enzymes that work in unusual conditions


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