The ExtremophilesThe Extremophiles

Typical conditions on Earth today are Typical conditions on Earth today are comfortable for typical present forms of comfortable for typical present forms of

life.life.• Average Temperature - 20 to 36°C (-4 to 97°F)• Pressure - 1 atm (sea level) to 0.5 atm (5500m)

• Salinity - Oceans are 3.5% salt• pH - Neutral (pure water) to slightly Basic

(sea water)• Radiation - Low levels = 0.003 Joules/kg/year

• Location - Land or Sea

Extremophiles are organisms Extremophiles are organisms adapted to living inadapted to living in

extreme environments.extreme environments.

• Most Extremophiles are bacteria.

• Some are eukaryotes and simple animals…. tube worms

• Were the first forms of life on Earth.

High temperatures are bad for most organisms

• Heat breaks down chlorophyll, stopping Heat breaks down chlorophyll, stopping photosynthesis.photosynthesis.

• Heat decreases the amounts of COHeat decreases the amounts of CO22 and O and O2 2

in water.in water.

• Heat breaks down proteins, causingHeat breaks down proteins, causingthem to stop working.them to stop working.

Thermophiles are organisms that thrive at high temperatures (>110°F)

• Found in hot springs and Found in hot springs and deep-sea hydrothermal vents.deep-sea hydrothermal vents.

• Have unique proteins & Have unique proteins & enzymes that work at high enzymes that work at high

temperatures.temperatures.

Most are ChemoautotrophsMost are Chemoautotrophs• Get their energy from Get their energy from

hydrogen sulfide or methanehydrogen sulfide or methane

Cold temperatures are bad for most organismsCold temperatures are bad for most organisms

• Freezing dehydrates cells Freezing dehydrates cells

• Cold slows the movement of nutrients & wastesCold slows the movement of nutrients & wastes

• Cold proteins and enzymes get stiff, inhibiting Cold proteins and enzymes get stiff, inhibiting their functiontheir function

• Frozen water can form needles-like crystals Frozen water can form needles-like crystals which puncture cell membraneswhich puncture cell membranes

PsychrophilesPsychrophiles are organisms that thrive at low temperatures (<15°C)

• Found in glaciers, arctic ice, Found in glaciers, arctic ice, snow, and soil deep in the snow, and soil deep in the

oceans.oceans.

• Have flexible enzymes and Have flexible enzymes and proteins that act like proteins that act like

antifreeze.antifreeze.

• Some are eukaryotes that live Some are eukaryotes that live by photosynthesis… snow by photosynthesis… snow

algae.algae.The methane ice worm , found in

Antartic ice cores, is a psychrophile that can survive temperatures from 0 to 5˚C. 

High salinity (too much salt) is bad for High salinity (too much salt) is bad for most organisms.most organisms.

• High salt dries out cells by drawing out water.

• High salinity promotes proteins to clump together, disrupting function.

• High Salinity limits the availability of oxygen.

Halophiles are organisms that thrive Halophiles are organisms that thrive in high in high concentrations of saltconcentrations of salt

• Live in water with 10x the salinity of the oceans• Dead Sea & Great Salt Lake.

• Extra ions reduce water movement out of the cell, stops drying out.

Halophiles have turned the land that surrounds the Great Salt Lake in Utah a reddish color. This happens to the land after flood waters

spread onto the land.

Salt Deposits on the Salt SeaSalt Deposits on the Salt Sea

The Acidity of solutions is measured by The Acidity of solutions is measured by its pH.its pH.

• High and low acidity can destroys High and low acidity can destroys proteins and DNA and inhibit their proteins and DNA and inhibit their

function.function.

Abnormally High or Low pH solutions Abnormally High or Low pH solutions can be bad for most organisms.can be bad for most organisms.

Acidophiles Acidophiles are organisms that thrive in highly acidic environments

• Survive in pH 0 (battery acid)Survive in pH 0 (battery acid)

• Some have an ability to neutralize their cellular interiorsSome have an ability to neutralize their cellular interiors

• Other acidophiles have evolved acid-stable proteins.Other acidophiles have evolved acid-stable proteins.

Ferroplasma acidarmanus can grow at 0 Ph! It can be Ferroplasma acidarmanus can grow at 0 Ph! It can be found in acid mine drainage.found in acid mine drainage.

Acidophiles - Organisms that thrive in extremely acidic habitats. Example: Found in Lechuguilla Cave, Carlsbad,

New Mexico, where the pH is 0.0…..about as acidic as battery acid!

Acidophiles found in a treatment plant in Wales

Radiation is hazardous to DNARadiation is hazardous to DNA• DNA is susceptible to radiation damage:DNA is susceptible to radiation damage:Minor Damage to DNA - limits self-repairMinor Damage to DNA - limits self-repair

Lethal Damage to DNA - results in cell deathLethal Damage to DNA - results in cell deathNon-Lethal Damage to DNA - leads to mutationsNon-Lethal Damage to DNA - leads to mutations

• Radiation Dose = Energy absorbed per kgRadiation Dose = Energy absorbed per kg10 Joules/kg is lethal to humans10 Joules/kg is lethal to humans60 Joules/kg kills 60 Joules/kg kills E. coli bacteriaE. coli bacteria

RadioresistantRadioresistant organisms can organisms can survive high doses of radiationsurvive high doses of radiation

• Deinococcus radiodurans can survive doses of 5000

Joules/kg

• Can absorb up to 15,000 Joules/kg with 37% viability

• Has very efficient DNA repair and carries 4 to 10

copies of its genomeDeinococcus radiodurans thrives in

the cooling ponds of nuclear reactors amid radioactivity levels

lethal to mammals.

EndolithsEndoliths are organisms that live inside rocks & between mineral

grains• Found as deep as 2 miles Found as deep as 2 miles

below the surface.below the surface.

• Most are Most are chemoautotrophschemoautotrophs

• Reproduce maybe once Reproduce maybe once per century….some per century….some

colonies live for colonies live for thousands of years?thousands of years?

These Brown Spherical Structures are Endoliths embedded in Quartz

XerophilesXerophiles are organisms that grow and reproduce in low water environments. They use

endospores, which are dehydrated cells surrounded by a thick protective cell wall, or

enter a anhydrobiosis state (no metabolic activity and little intracellular water). Even after 30

millions years, some bacterial spores have been revived.

The Atacama Desert of northern Chile is the driest non-arctic place on Earth.

• Virtually sterile desert 100 times more Virtually sterile desert 100 times more dry than California’s Death Valley.dry than California’s Death Valley.

• No rainfall recorded in some regions for No rainfall recorded in some regions for the past 400 years!the past 400 years!

Results of a 2003 study for life in the Results of a 2003 study for life in the Atacama Desert….Atacama Desert….

• No bacteria were found down to 4 inches….

• A later study found viable bacteria at depth of 1 foot!

• It Turns out that Life can exist It Turns out that Life can exist even in the driest environments even in the driest environments

as long as there is at least a little as long as there is at least a little liquid water.liquid water.

NASA rover, designed to search for life in the Atacama

Desert.

The record holder for reviving dormant bacteria is Strain 2-9-3, found in sea salt, which was revived after 250 million years of

dormancy.

Tardigrades can withstand the highest variety of extreme Tardigrades can withstand the highest variety of extreme

conditions and are capable of entering a low hydration conditions and are capable of entering a low hydration state called tun in which they use .01% metabolic activity. state called tun in which they use .01% metabolic activity. They can survive a decade without water in the tun state! They can survive a decade without water in the tun state! These organisms look like bears, and inhabit almost every These organisms look like bears, and inhabit almost every

environment on Earth. environment on Earth.

Tardigrades are about 0.1 - 0.5 mmTardigrades are about 0.1 - 0.5 mm

Studying the extremes life forms on Earth can help us in our search for life elsewhere in the Universe.

• The discovery of the existence of The discovery of the existence of extremophiles greatly extends our extremophiles greatly extends our

understanding of the range of possible understanding of the range of possible environments for life.environments for life.

• Extremophiles were the first life-forms on Extremophiles were the first life-forms on Earth.Earth.

• No organisms are known that can survive No organisms are known that can survive without liquid water.without liquid water.

What We’ve Learned

Could Extremophiles survive Could Extremophiles survive elsewhere in our Solar System?elsewhere in our Solar System?

MarsMars• Mars is one of the first planets most people think of when searching for life outside of Earth. It is cold and dry but with the

possibility of liquid water subsurface, organisms such as Tardigrades or Radioresistants could live there. Tardigrades only

requires basalt + water and a radioresistant could survive the radiation, dryness and low atmospheric pressure.

Jupiter’s Moons• Moons such as Europa, Ganymede and Callisto are very

promising because they are believed to have oceans below there icy surfaces.

• Thermophiles could survive, endoliths if there are rock and water combinations, or even psychrophiles on the icy surface of the

moons.

Saturn’s Titan• The Cassini-Huygens

mission surveyed Titan and found similar hydrocarbon

compounds in its thick atmosphere.

Especially promising is Saturn’s moon Enceladus. Pictures taken by the Cassini-Huygens spacecraft show liquid

water Geysers. Not only is there water, but carbon and energy are present… the perfect ingredients for life.

Liquid Water Liquid Water GeysersGeysers

VenusThe Clouds in Venus' The Clouds in Venus'

stratosphere are stratosphere are perfect conditions for perfect conditions for

acidophiles. acidophiles. The clouds The clouds are cooler than the are cooler than the

900˚F surface and there 900˚F surface and there are acid drops in the are acid drops in the

clouds where clouds where acidophiles could acidophiles could

survive. survive.

CometsComets could host organisms such as

psychrophiles. These organisms could have a dormancy periods and only reproduce when

they are in a habitable zone.