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1、极端环境微生物（Extremophiles）,Life in extreme environments Microbes that live in conditions that would kill other creatures.Microbes that Love of extremes对其它生物是极端或致死的环境,火星,木卫二,生活在极端自然环境中的微生物是生命的奇迹，它们蕴涵着生命进化历程的丰富信息，代表着生命对于环境的极限适应能力，是生物遗传和功能多样性最为丰富的宝藏。,1.揭示生命的起源与生命的演化。2.生命机制研究：阐明生物多样性形成机制、生物 适应环境机制3.提供了在地球以外
2、其它环境寻找生命的依据4.实际应用：极端微生物资源在环境保护和修复、人类健康、生物技术等方面的利用,研究意义：,极端酶（extremozymes）,极端酶具有潜在的应用价值嗜热酶嗜冷酶Taq DNA聚合酶从水生栖热菌(Thermusaquaticus)中分离提取的嗜热酶该菌是1969年从美国黄石国家森林公园火山温泉中分离的,极端环境微生物thermophiles psychrophiles acidophiles alkophiles halophiles barophiles Microorganisms resistant to radiation,1.High temperature e
3、nvironments and Thermophiles1.1 background Hot springs(陆地热泉)Shallow submarine hydrothermal systems(浅海底热泉)abyssal hot vents(深海火山口),许多热泉的温度接近或达到沸腾 火山喷气孔的温度可达到150500C 海底火山热气孔的温度可达到350 C,Thomas D.Brock Brock Biology of Microorganisms Yellowstone National Park 82C 热泉发现了细菌 水生栖热菌(Thermus aquaticus)崭新的世界、新的
4、研究领域,在热泉处（白色）由于温度高，没有光合细菌，随着温度降低，开始出现光合细菌，颜色变深,old faithful erupts(忠诚喷泉)，每次能把75001.2万加仑的泉水喷向高空，水柱高达55米！滚烫的热水遇冷气后又在空中凝结成白色云柱，壮观中还透出一些妩媚,(Left)The orange scum is bacterial in origin.New Zealand.1999.(Right)The rusty color on the rocks of this volcanic pool is Sulfolobus solfataricus.Italy.,1.2 嗜热菌(The
5、rmophiles)的主要类群 To date,over 50 thermophiles are known.The most extreme is Pyrolobus fumarii,which can multiply in temperatures up to 113C.optimal temperature:6062C:Procaryote 7073C:photosynthetic bacteria over 100C:a few unusually heat-adapted Archaea called hyperthermophiles.,Temperatures approach
6、ing 100 C normally denature proteins and nucleic acids,and increase the fluidity of membranes to lethal levels.Chlorophyll degrades above 75C,excluding photosynthesis,1.3 适应高温的分子适应性 How can hyperthermophiles maintain the integrity of their macromolecules at temperatures where the chemical degradatio
7、n of DNA and proteins is greatly accelerated?细胞膜中膜脂高饱和度脂肪酸 蛋白质的热稳定性 遗传物质稳定性,2.Low temperature and cold adapted microorganisms The Majority of the Earths ecosystems are Cold Environments,90 percent of the worlds oceans are“cold”Cold polar seas and soils,Glaciers,deep-sea areas High mountains covered
8、with snowIce and brine pools from polar regions,High altitude snow fields and other high altitude habitats,Caves,Refrigerators,Upper atmosphere,Cold environments,Most of the oceans are at approximately 5 C.,The poles cover significant areas and temperatures rarely exceed 0 C,“Red snow”is common in s
9、now fields,C.nivalis grows in melt water It is photosynthetic and contains chlorophyll.As temperatures become extreme it produces resistant spores which contain a photoprotective red pigment.The spores become concentrated at the snow surface.,Bacteria within ice fissures,As water freezes,solutes are
10、 excluded.These accumulate as small inclusions of brine.The high salt concentrations prevent freezing,2.1 嗜冷菌(psychrophiles)和耐冷菌(psychrotrophos)cold adapted microorganisms psychrophiles:终年常冷的环境 最低 最适 最高温度 0 C,15 C 20 C 05 C 20 C 20 C psychrophiles:具有温度波动的环境 最低温度 最适温度 最高温度-120 C 15 C 20 C,微生物的种类 真核生物
11、：yeasts,fungi,algae,lichens 原核生物：Gram negative bacteria Pseudomonas,Vibrio,Achromobacter,Flavobacterium,Cytophaga 严格的厌氧菌很少 鱼和食品的病原菌 是海水中异样菌的主要类群,What happens to cells when water gets colder?Lipid membranes become semi-crystalline and lose integrity at low temperatures.When water freezes it makes ice
12、 crystals that are spiky and hard and destructive to cells.Also,when movements slow down,membranes tend to gel and transportation of ions across the cell membrane slows down.It is harder and harder for an organism to grow.Enzyme activity becomes very slow.Ice crystal formation can disrupt cell structure.,2.2 适应机理 细胞膜的特性 蛋白质结构的特殊性 冷休克蛋白(cold shock protein)冷活性酶,思考题1.从极端环境微生物的角度分析生命的多样性 及形成原因2.如何利用极端环境微生物？,
