极端环境微生物VIP专享VIP免费

极端环境微生物（Extremophiles）LifeinextremeenvironmentsMicrobesthatliveinconditionsthatwouldkillothercreatures.MicrobesthatLoveofextremes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TaqDNA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thermophilespsychrophilesacidophilesalkophileshalophilesbarophilesMicroorganismsresistanttoradiation1.HightemperatureenvironmentsandThermophiles1.1backgroundHotsprings(陆地热泉)Shallowsubmarinehydrothermalsystems(浅海底热泉)abyssalhotvents(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150~500°C海底火山热气孔的温度可达到350°CThomasD.BrockBrockBiologyofMicroorganismsYellowstoneNationalPark82°C热泉发现了细菌水生栖热菌(Thermusaquaticus)崭新的世界、新的研究领域在热泉处（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oldfaithfulerupts(忠诚喷泉)，每次能把7500~1.2万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)Theorangescumisbacterialinorigin.NewZealand.1999.(Right)TherustycolorontherocksofthisvolcanicpoolisSulfolobussolfataricus.Italy.1.2嗜热菌(Thermophiles)的主要类群Todate,over50thermophilesareknown.ThemostextremeisPyrolobusfumarii,whichcanmultiplyintemperaturesupto113°C.optimaltemperature:60~62C:Procaryote70~73C:photosyntheticbacteriaover100C:afewunusuallyheat-adaptedArchaeacalledhyperthermophiles.Temperaturesapproaching100°Cnormallydenatureproteinsandnucleicacids,andincreasethefluidityofmembranestolethallevels.Chlorophylldegradesabove75°C,excludingphotosynthesis1.3适应高温的分子适应性HowcanhyperthermophilesmaintaintheintegrityoftheirmacromoleculesattemperatureswherethechemicaldegradationofDNAandproteinsisgreatlyaccelerated?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.LowtemperatureandcoldadaptedmicroorganismsTheMajorityoftheEarth’secosystemsareColdEnvironments,90percentoftheworldsoceansare“cold”Coldpolarseasandsoils,Glaciers,deep-seaareasHighmountainscoveredwithsnowIceandbrinepoolsfrompolarregions,Highaltitudesnowfieldsandotherhighaltitudehabitats,Caves,Refrigerators,UpperatmosphereColdenvironmentsMostoftheoceansareatapproximately5C.Thepolescoversignificantareasandtemperaturesrarelyexceed0C“Redsnow”iscommoninsnowfieldsC.nivalisgrowsinmeltwaterItisphotosyntheticandcontainschlorophyll.Astemperaturesbecomeextremeitproducesresistantsporeswhichcontainaphotoprotectiveredpigment.Thesporesbecomeconcentratedatthesnowsurface.BacteriawithinicefissuresAswaterfreezes,solutesareexcluded.Theseaccumulateassmallinclusionsofbrine.Thehighsaltconcentrationspreventfreezing2.1嗜冷菌(psychrophiles)和耐冷菌(psychrotrophos)coldadaptedmicroorganismspsychrophiles:终年常冷的环境最低最适最高温度0°C,15°C20°C0~5°C20°C20°Cpsychrophiles:具有温度波动的环境最低温度最适温度最高温度-12~0ºC<15ºC<20ºC微生物的种类真核生物：yeasts,fungi,algae,lichens原核生物：GramnegativebacteriaPseudomonas,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Whathappenstocellswhenwatergetscolder?Lipidmembranesbecomesemi-crystallineandloseintegrityatlowtemperatures.Whenwaterfreezesitmakesicecrystalsthatarespikyandhardanddestructivetocells.Also,whenmovementsslowdown,membranestendtogelandtransportationofionsacrossthecellmembraneslowsdown.Itisharderandharderforanorganismtogrow.Enzymeactivitybecomesveryslow.Icecrystalformationcandisruptcellstructure.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(coldshockprotein)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？