ExtremophilesPPT演示课件

.,Extremophiles,Life on the edge,Life at High Temperatures, Thomas M. Brock,.,Extremophiles,Images from NASA, /planets/,.,Goals,Overview of ExtremophilesReview some biologyGive some applicationsMotivate you to study Microbiology!,.,Introduction to Extremophiles,What are they?Microbes living where nothing else can How do they survive?ExtremozymesWhy are they are interesting?Extremes fascinate usLife on other planetsPractical applications are interestingInterdisciplinary lessonsGenetic Prospecting,.,Extremo - phile,Definition - Lover of extremesHistorySuspected about 30 years agoKnown and studied for about 20 yearsTemperature extremesboiling or freezing, 1000C to -10C (212F to 30F) Chemical extremesvinegar or ammonia (9 pH)highly salty, up to ten times sea waterHow we sterilize & preserve foods today,.,Extreme Temperatures,Thermophiles - High temperatureThermal vents and hot springsMay go hand in hand with chemical extremesPsychrophiles - Low temperatureArctic and Antarctic1/2 of Earths surface is oceans between 10C & 40CDeep sea 10C to 40CMost rely on photosynthesis,.,Thermophiles,Obsidian Pool,Yellowstone NationalParkHydrothermal Vents,.,Psychrophiles,.,Chemical Extremes,Acidophiles - AcidicAgain thermal vents and some hot springsAlkaliphiles - AlkalineSoda lakes in Africa and western U.S.Halophiles - Highly Salty Natural salt lakes and manmade poolsSometimes occurs with extreme alkalinity,.,Acidophiles,pH 0-1 of watersat Iron Mountain,.,Alkaliphile,e.g. Mono Lakealkaline soda lake, pH 9salinity 8%,.,Halophiles,solar salternsOwens Lake, Great Salt Lakecoastal splash zonesDead Sea,.,Survival,Temperature extremesEvery 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 extremesInterior of cell is “normal”Exterior protects the cellAcidophiles and Alkaliphiles sometimes excrete protective substances and enzymesAcidophiles often lack cell wallSome moderate halophiles have high concentrations 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 specificLock and key analogy,Substrate A,Product B,Product C,.,What are enzymes?,Activation energyEnzymes allow reactions with lower energy,.,What are enzymes?,Enzymes are just a proteinThey can be destroyed byHeat, acid, baseThey can be inhibited byCold, saltTry doing this with an egg white or milkProtein is a major component of both,.,Practical Applications,ExtremozymesEnzyme from ExtremophileIndustry & MedicineWhat if you want an enzyme to work In a hot factory?Tank of cold solution?Acidic pond?Sewage (ammonia)?Highly salty solution?,.,One solution,Pay a genetic engineer to design a “super” enzymes.Heat resistant enzymesSurvive low temperaturesAble to resist acid, alkali and/or saltThis could take years and lots of money,.,Extremophiles got there first,Nature has already given us the solutions to these problemsExtremophiles have the enzymes that work in extreme conditions,Endolithic algae from Antarctica; Hot springs in Yellowstone National Park, 1998 Reston Communications, /astro/extreme.html,.,Thermophiles,Most interesting practical applications so farMany industrial processes involve high heat450C (113F) is a problem for most enzymesFirst Extremophile found 30 years ago,Life at High Temperatures, Thomas M. Brock,.,PCR - Polymerase Chain Reaction,Allows amplification of small sample of DNA using high temperature processTechnique is about 10 years oldDNA fingerprints - samples from crime sceneGenetic Screening - swab from the mouthMedical 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 coldEnzymes to work on foods that need to be refrigeratedPerfumes - most dont tolerate high temperaturesCold-wash detergents,Algal mats on an Antarctic lake bottom, 1998 Reston Communications, /astro/extreme.html,.,Acidophiles,Enzymes used to increase efficiency of animal feedsenzymes help animals extract nutrients from feedmore efficient and less expensive,Life at High Temperatures, Thomas M. Brock,.,Alkaliphiles,“Stonewashed” pantsAlkaliphilic enzymes soften fabric and release some of the dyes, giving worn look and feelDetergentsEnzymes to dissolve proteins or fatsAlkaliphilic enzymes can work with detergents,.,Halophiles,What is a halophile?Diversity of Halophilic OrganismsOsmoregulation“Compatible Solute” Strategy“Salt-in” StrategyInteresting Facts and Applications,.,What is a halophile?,The word halophile means “salt loving”.A halophile is an organism that can grow in higher salt concentrations than the norm.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 35 % salt. This is extreme compared to seawater which is only 3% salt.,.,Diversity of Halophilic Organisms,Halophiles are a broad group that can be found in all three domains of life.They are found in salt marshes, subterranean salt deposits, dry soils, salted meats, hypersaline seas, and salt evaporation pools.,.,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.,.,Osmoregulation,Living in high salinity poses a serious stress that halophiles have overcome through special processes or adaptations.The stress lies in the microbes ability to 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 cells water will move into the solution causing the cell to plasmolyze.,.,Osmoregulation,Halophiles have adapted to life at high salinity in many different ways.One way is through the modification of their external cell walls. They tend to have negatively charged proteins on the outside of their cell walls that stabilize it by binding to positively charged sodium ions in their external environments. If salt concentrations decline their cell walls may become unstable and break down.,.,“Compatible Solute” Strategy,There are two strategies that halophiles have evolved to deal with high salt environments.In the “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.,.,“Compatible Solute” Strategy,Compatible solutes include polyols such as glycerol, sugars and their derivatives, amino acids and their derivatives, and quaternary amines such as glycine betaine.Energetically this is an expensive process.Autotrophs use between 30 to 90 molecules of ATP to synthesize one molecule of the compatible solutes. Heterotrophs use between 23 to 79 ATP.,.,“ Compatible Solute” Strategy,Energy is also expended in pumping out salts that dissolve into the cell.The uptake of available compatible solutes in the environment is an adaptation they have evolved to reduce the energy cost of living in high salt concentrations.,.,“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 uniport system. 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 example of an extreme halophile,Halobacterium are members of the halophile group in the domain archaea. They are widely researched for their extreme halophilism and unique structure.They require salt concentrations between 15% to 35% sodium chloride to live.They use the “salt-in” strategy.They produce ATP by respiration or by bacteriorhodopsin.,.,Halobacterium,They 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,Current applications using halophiles include:the extraction of carotene from carotene rich halobacteria and halophilic algae that can then be us