嗜酸微生物总结

CHAPTER1MICROORGANISMSINVOLVEDINBIOLEACHINGANDNUCLEICACID-BASEDMOLECULARMETHODSFORTHEIRIDENTIFICATIONANDQUANTIFICATIONAXELSCHIPPERSGeomicrobiology,FederalInstituteforGeosciencesandNaturalResources,Stilleweg2,D-30655Hannover,Germany.E-mail:a.schippers@bgr.de1.INTRODUCTIONBioleachingisthebiologicalconversionofaninsolublemetalcompoundintoawatersolubleform.Incaseofmetalsulfidebioleaching,metalsulfidesareoxidizedtometalionsandsulfatebyaerobic,acidophilicFe(II)and/orsulfur-compoundoxidizingBacteriaorArchaea.Bioleachinginvolveschemicalandbiologicalreactions.Despitemolecularoxygenbeingthefinalelectronacceptorfortheoverallmetalsulfidebioleachingprocess,Fe(III)ionsaretherelevantoxidizingagentforthemetalsulfides.ThemetalsulfideoxidationitselfisachemicalprocessinwhichFe(III)ionsarereducedtoFe(II)ionsandthesulfurmoietyofthemetalsulfideisoxidizedtosulfate,andvariousintermediatesulfurcompounds,e.g.elementalsulfur,polysulfide,thiosulfate,andpolythionates.Forexampletheoxidationofsphalerite(ZnS)toelementalsulfurisgiveninthefollowingequation:(1)ZnS+2Fe3+→Zn2++0�125S8+2Fe2+Becauseoftwodifferentgroupsofmetalsulfidesexist,twodifferentmetalsulfideoxidationmechanismshavebeenproposed,namelythethiosulfatemechanism(foracid-insolublemetalsulfides,suchaspyrite)andthepolysulfidemechanism(foracid-solublemetalsulfides,e.g.sphaleriteorchalcopyrite,CuFeS2�.Thesemecha-nismsexplaintheoccurrenceofallinorganicsulfurcompoundswhichhavebeendetectedinthecourseofmetalsulfideoxidation(forreviewsee:Sandetal.,2001;Rohwerderetal.,2003;Schippers,2004;Chapter2).Theroleofthemicroorganismsinthebioleachingprocessistooxidizetheproductsofthechemicalmetalsulfideoxidation(Fe(II)ionsandsulfur-compounds)inordertoprovideFe(III)andprotons,themetalsulfideattackingagents.Inaddition,protonproductionkeepsthepHlowandthus,theFeionsinsolution.3E.R.DonatiandW.Sand(eds.),MicrobialProcessingofMetalSulfides,3–33.©2007Springer.4SCHIPPERSAerobic,acidophilicFe(II)oxidizingBacteriaorArchaeaprovideFe(III)bythefollowingequation:(2)2Fe2++0�5O