Extremophiles Life on edge Life at High Temperatures, Thomas M. Brock.
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Transcript of Extremophiles Life on edge Life at High Temperatures, Thomas M. Brock.
Extremophiles
Life on edge
Life at High Temperatures, Thomas M. Brock
Extremophiles
Images from NASA, http://pds.jpl.nasa.gov/planets/
Extraterrestrial microbial life-does it exist?
Lecture Aims
What are Extremophiles- an introduction Strategies for growth & survival Biotechnology
Introduction to Extremophiles What are Extremophiles
Live where nothing else can How do they survive?
Extremozymes (more details later) Why are they are interesting?
Extremes fascinate us Life on other planets Life at boiling temperatures
Practical applications are interesting Interdisciplinary lessons
Genetic Prospecting
Extremophile Definition - Lover of extremities History
First suspected in 1950’s Extensively studied since 1970’s
Temperature extremes Boiling or freezing, 1000C to -10C Chemical extremes Vinegar or ammonia (<5 pH or >9 pH) Highly saline, up to x10 sea water
How we sterilize & preserve foods today
Extreme Temperatures
Thermophiles - High temperature 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 1-40C
Deep sea –10C to 40C Most rely on photosynthesis
Thermophiles
Hydrothermal Vents- Black smokers at 350 oC
Obsidian Pool,Yellowstone National Park
Psychrophiles
Chemical Extremes
Acidophiles - Acidic Again some thermal vents & hot springs
Alkaliphiles - Alkaline Soda lakes in Africa and Western U.S.
Halophiles - Highly saline Natural salt lakes and manmade pools Sometimes occurs with extreme
alkalinity
Acidophiles
pH 0-1 of watersat Iron Mountain
Alkaliphiles
Mono Lake- alkalinesoda lake, pH 9 &salinity 8%
Halophiles
Dead Sea
Great Salt Lake coastalsplash zones
Solar salterns Owens Lake
Survival Temperature extremes
Every part of microbe must function at extreme
“Tough” enzymes for Thermophiles “Efficient” enzymes for Psychrophiles
Many enzymes from these microbes are interesting
Life at High Temperatures, Thomas M. Brock
Survival Chemical extremes
Interior of cell is “normal” Exterior protects the cell
Acidophiles and Alkaliphiles sometimes excrete protective substances and enzymes
Acidophiles often lack cell wall Some moderate halophiles have high concs
of a solute inside to avoid “pickling” Some enzymes from these microbes are
interesting
What are enzymes? Definition - a protein that catalyses
(speeds up) chemical reactions without being changed
What are enzymes? Enzymes are specific
Lock and key analogy
Enzyme
Substrate A
Product B
Product C
What are enzymes? Activation energy
Enzymes allow reactions with lower energyEn
erg
y
Time
Without Enzyme
With Enzyme
What are enzymes? Enzymes are just a protein
They can be destroyed by Heat, acid, base
They can be inhibited by Cold, salt
Heat an egg white or add vinegar to milk Protein is a major component of both-
denatures
Practical Applications Extremozymes
Enzyme from Extremophile Industry & Medicine
What if you want an enzyme to work In a hot factory? Tank of cold solution? Acidic pond? Sewage (ammonia)? Highly saline solution?
One solution Pay a genetic engineer to design a
“super” enzymes... Heat resistant enzymes Survive low temperatures Able to resist acid, alkali and/or salt
This could take years and lots of money
Extremophiles got there first Nature has already given us the
solutions to these problems Extremophiles have the enzymes
that work in extreme conditions
Endolithic algae from Antarctica; Hot springs in Yellowstone National Park, © 1998 Reston Communications, www.reston.com/astro/extreme.html
Thermophiles Most interesting, with practical applications
Many industrial processes involve high heat 450C (113F) is a problem for most enzymes First Extremophile found in 1972
Life at High Temperatures, Thomas M. Brock
PCR - Polymerase Chain Reaction
Allows amplification of small sample of DNA using high temperature process Technique is about 10 years old DNA fingerprints - samples from crime
scene Genetic Screening - swab from the mouth Medical Diagnosis - a few virus particles
from blood Thermus aquaticus or Taq
Life at High Temperatures, Thomas M. Brock
Psychrophiles Efficient enzymes to work in the cold
Enzymes to work on foods that need to be refrigerated
Perfumes - most don’t tolerate high temperatures
Cold-wash detergents
Algal mats on an Antarctic lake bottom, © 1998 Reston Communications, www.reston.com/astro/extreme.html
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
Alkaliphiles
“Stonewashed” pants Alkaliphilic enzymes soften fabric and
release some of the dyes, giving worn look & feel
Detergents Enzymes dissolve proteins or fats Detergents do not inhibit alkaliphilic
enzymes
Halophiles What is a halophile? Diversity of Halophilic Organisms Adptation Strategies
Osmoregulation-“Compatible Solute” Strategy
“Salt-in” Strategy
Interesting Facts and Applications
What is a halophile? Halophile = “salt loving; can grow in higher
salt concentrations Based on optimal saline environments
halophilic organisms can be grouped into three categories: extreme halophiles, moderate halophiles, and slightly halophilic or halotolerant organisms
Some extreme halophiles can live in solutions of 25 % salt; seawater = 2% salt
Diversity of Halophilic Organisms
Halophiles are a broad group &t can be found in all three domains of life.
Found in salt marshes, subterranean salt deposits, dry soils, salted meats, hypersaline seas, and salt evaporation ponds.
Unusual Habitats A Pseudomonas species lives on a
desert plant in the Negev Desert- the plant leaves secretes salt through salt glands.
A Bacillus species is found in the nasal cavities of desert iguanas- iguanas nasal cavities have salt glands which secrete KCl brine during osmotic stress.
Osmoregulation Halophiles maintain an internal
osmotic potential that equals their external environment.
Osmosis is the process in which water moves from an area of high concentration to an area of low concentration.
Osmoregulation In order for cells to maintain their water
they must have an osmotic potential equal to their external environment.
As salinity increases in the environment its osmotic potential decreases.
If you placed a non halophilic microbe in a solution with a high amount of dissolved salts the cell’s water will move into the solution causing the cell to plasmolyze.
Osmoregulation Halophiles have adapted to life at high
salinity in many different ways. Structural modification of external cell
walls- posses negatively charged proteins on the outside which bind to positively charged sodium ions in their external environments & stabilizes the cell wall break down.
“Compatible Solute” Strategy
Cells maintain low concentrations of salt in their cytoplasm by balancing osmotic potential with organic, compatible solutes.
They do this by the synthesis or uptake of compatible solutes- glycerol, sugars and their derivatives, amino acids and their derivatives & quaternary amines such as glycine betaine.
Energetically synthesizing solutes is an expensive process. Autotrophs use between 30 to 90 molecules of
ATP to synthesize one molecule of compatible solute.
Heterotrophs use between 23 to 79 ATP.
“Salt-in” Strategy Cells can have internal concentrations
that are osmotically equivalent to their external environment.
This “salt-in” strategy is primarily used by aerobic, extremely halophilic archaea and anaerobic bacteria.
They maintain osmotically equivalent internal concentrations by accumulating high concentrations of potassium chloride.
“Salt-in” Strategy Potassium ions enter the cell
passively via a uniporter. Sodium ions are pumped out. Chloride enters the cell against the membrane potential via cotransport with sodium ions.
For every three molecules of potassium chloride accumulated, two ATP are hydrolyzed making this strategy more energy efficient than the “compatible solute” strategy.
“Salt-in” Strategy To use this strategy all enzymes and
structural cell components must be adapted to high salt concentrations to ensure proper cell function.
Halobacterium: an extreme halophile Halobacterium are members of domain
archaea. Widely researched for their extreme
halophilism and unique structure. Require salt concentrations between
15% to saturation to live. Use the “salt-in” strategy. Produce ATP by respiration or by
bacteriorhodopsin.
Halobacterium May also have halorhodopsin that
pumps chloride into the cell instead of pumping protons out.
The Red Sea was named after halobacterium that turns the water red during massive blooms.
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.
Applications
The extraction of carotene from carotene rich halobacteria and halophilic algae that can then be used as food additives or as food-coloring agents.
The use of halophilic organisms in the fermentation of soy sauce and Thai fish sauce.
Applications Other possible applications being
explored: Increasing crude oil extraction (MEOR) Genetically engineering halophilic
enzymes encoding DNA into crops to allow for salt tolerance
Treatment of waste water (petroleum)
Conclusions Halophiles are salt tolerant organisms. They are widespread and found in all
three domains. The “salt-in” strategy uses less energy
but requires intracellular adaptations. Only a few prokaryotes use it.
All other halophiles use the “compatible solute” strategy that is energy expensive but does not require special adaptations.
Genetic prospecting
What is it? Think of a hunt for the genetic gold
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 The practical applications are
interesting