ReviewRemember 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)-most have peptidoglycan in their

cell walls-flagella are made with a globular

protein called flagellin- no 9+2 arrangement

Cytosol Granules(Small chunks of food)

Locomotion (Methods of Movement)

Bacterial Flagellum- lacks microtubules

Pili- short, thin appendages

Bacteria

E. coli

E. coli

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

Oxygen Preferences

obligate aerobes must have oxygen obligate anaerobes cannot live in

oxygen facultative anaerobes can grow

with or without oxygen

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:

do not have peptidoglycan in their cell walls

have ribosomes similar to eukaryotes

have unique lipids in their plasma (cell) membranes

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 Methanogens Halophiles Thermoacidophiles = live in

extremely hot, acid environments

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

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

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.

HalophileEnvironmentssolar salternsOwens Lake, Great Salt Lake,coastal splash zones,Dead Sea

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

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

ThermophileEnvironments

Hydrothermal Vents in the ocean, and

Obsidian Pool in Yellowstone National Park

Psychrophile Environments

Alan Hills Ice Field: Antarctica

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 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

Acidophiles Enzymes used to increase

efficiency of animal feeds– enzymes help animals

extract nutrients from feed»more efficient and less expensive

Life at High Temperatures, Thomas M. Brock

Acidophile Environments

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

Alkaliphile Environments

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

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 SurvivalWhile 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

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

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

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