2Typical conditions on Earth today are comfortable for typical present forms of life. Average Temperature to 36°C (-4 to 97°F)Pressure - 1 atm (sea level) to 0.5 atm (5500m)Salinity - Oceans are 3.5% saltpH - Neutral (pure water) to slightly Basic (sea water)Radiation - Low levels = Joules/kg/yearLocation - Land or Sea
3Extremophiles are organisms adapted to living in extreme environments.
4Most Extremophiles are bacteria. Some are eukaryotes and simple animals…. tube wormsWere the first forms of life on Earth.
5High temperatures are bad for most organisms Heat breaks down chlorophyll, stopping photosynthesis.Heat decreases the amounts of CO2 and O2 in water.Heat breaks down proteins, causingthem to stop working.
6Thermophiles are organisms that thrive at high temperatures (>110°F) Found in hot springs and deep-sea hydrothermal vents.Have unique proteins & enzymes that work at high temperatures.Most are ChemoautotrophsGet their energy from hydrogen sulfide or methane
7Cold temperatures are bad for most organisms Freezing dehydrates cellsCold slows the movement of nutrients & wastesCold proteins and enzymes get stiff, inhibiting their functionFrozen water can form needles-like crystals which puncture cell membranes
8Psychrophiles are organisms that thrive at low temperatures (<15°C) Found in glaciers, arctic ice, snow, and soil deep in the oceans.Have flexible enzymes and proteins that act like antifreeze.Some are eukaryotes that live by photosynthesis… snow algae.The methane ice worm , found in Antartic ice cores, is a psychrophile that can survive temperatures from 0 to 5˚C.
9High salinity (too much salt) is bad for 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.
10Halophiles are organisms that thrive in high concentrations of salt Live in water with 10x the salinity of the oceansDead Sea & Great Salt Lake.Extra ions reduce water movement out of the cell, stops drying out.
11Halophiles 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.
13The Acidity of solutions is measured by its pH. Abnormally High or Low pH solutions can be bad for most organisms.The Acidity of solutions is measured by its pH.High and low acidity can destroys proteins and DNA and inhibit their function.
14Acidophiles are organisms that thrive in highly acidic environments Ferroplasma acidarmanus can grow at 0 Ph! It can befound in acid mine drainage.Survive in pH 0 (battery acid)Some have an ability to neutralize their cellular interiorsOther acidophiles have evolved acid-stable proteins.
15Acidophiles found in a treatment plant in Wales 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
16Radiation is hazardous to DNA DNA is susceptible to radiation damage:Minor Damage to DNA - limits self-repairLethal Damage to DNA - results in cell deathNon-Lethal Damage to DNA - leads to mutationsRadiation Dose = Energy absorbed per kg10 Joules/kg is lethal to humans60 Joules/kg kills E. coli bacteria
17Radioresistant organisms can survive high doses of radiation Deinococcus radiodurans can survive doses of 5000 Joules/kgCan absorb up to 15,000 Joules/kg with 37% viabilityHas 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.
18Endoliths are organisms that live inside rocks & between mineral grains Found as deep as 2 miles below the surface.Most are chemoautotrophsReproduce maybe once per century….some colonies live for thousands of years?These Brown Spherical Structures are Endoliths embedded in Quartz
19Xerophiles 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.
20No rainfall recorded in some regions for the past 400 years! The Atacama Desert of northern Chile is the driest non-arctic place on Earth.Virtually sterile desert 100 times more dry than California’s Death Valley.No rainfall recorded in some regions for the past 400 years!
21Results of a 2003 study for life in the 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 even in the driest environments as long as there is at least a little liquid water.NASA rover, designed to search for life in the Atacama Desert.
22The 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 conditions and are capable of entering a low hydration state called tun in which they use .01% metabolic activity. They can survive a decade without water in the tun state! These organisms look like bears, and inhabit almost every environment on Earth. Tardigrades are about mm
23Extremophiles were the first life-forms on Earth. Studying the extremes life forms on Earth can help us in our search for life elsewhere in the Universe.What We’ve LearnedThe discovery of the existence of extremophiles greatly extends our understanding of the range of possible environments for life.Extremophiles were the first life-forms on Earth.No organisms are known that can survive without liquid water.
24Could Extremophiles survive elsewhere in our Solar System?
25MarsMars 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.
26Jupiter’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.
27Saturn’s TitanThe Cassini-Huygens mission surveyed Titan and found similar hydrocarbon compounds in its thick atmosphere.
28Especially promising is Saturn’s moon Enceladus 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 Geysers
29VenusThe Clouds in Venus' stratosphere are perfect conditions for acidophiles. The clouds are cooler than the 900˚F surface and there are acid drops in the clouds where acidophiles could survive.
30CometsComets could host organisms such as psychrophiles. These organisms could have a dormancy periods and only reproduce when they are in a habitable zone.