Enzymes in the Environment: Activity, Ecology and Applications - Chapter 3 pdf
Enzymes in the Environment: Activity, Ecology and Applications - Chapter 3 pdf
... (18,21 ,35 ,36 ) and probablyalso in the extracellular release of endo -enzymes by these bacteria (37 ,38 ). By hydrolyzingmacromolecular linkages in an endo- fashion (i.e., hydrolyzing the nonterminal linkages in ... supply the entire microbial commu-nity including the free-living bacteria. A key to understanding this paradox lies in the enhanced individual enzyme activity of the attached bacteria (18,21 ,35 ,36 ) ... forchitin-hydrolyzing activity by using MUF-β-d-N, N′-diacetylchitobioside, and chitobiaseactivity was then assayed in protein extracts prepared from the positive clones. The chi-tinases of marine bacteria...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 1 ppsx
... Inc.Thereisthepotentialtouseanintegratedmeasurementofanumberofenzymeactivities(asdiscussedlater),inconjunctionwithotherphysical,chemical,andmicrobio-logicalmeasurements,inassessingsoilquality.Somehydrolaseactivitiesdonotshowwideseasonalvariation,probablybecauseofthelargeamountofactivityassociatedwithenzymesstabilizedbysoilcolloids.Thisprovidesagreatadvantageovermicrobiologicalmeasurementssuchasrespiration,whichvarysowidelywithinaseasonoronayear-to-yearbasisandmakeitdifficulttofindtrendsoridentifytheimpactsofdifferentmanage-mentsystems.Dehydrogenaseactivityisanintracellularprocessthatoccursineveryviablemicro-bialcellandismeasuredtodetermineoverallmicrobiologicalactivityofsoil(40,41) .The problemwiththisisthattheelectronacceptors(2 ,3, 5-triphenyltetrazoliumchloride[TTC](seealsop.19)or2-p-Iodophenyl -3 - p-nitrophenyl-5-phenyltetrazoliumchloride[INT](seealsop. 13) )usedintheassaysarenotveryeffective,andthusthemeasurementsmayunderestimatethetruedehydrogenaseactivity(41).Anotherpotentiallyconfusingaspectofthesestudiesarisesasaconsequenceofsoilcollectionandpretreatment.AccordingtoNannipieriandcoworkers(41),enzymeactivitymeasurementsarecarriedoutafterremovalofvisibleanimalsandplantdebrisandonsievedsoilsamplesunderlaboratoryconditions.Thusthemeasuredactivitiesofthesesamplesmaydependonthemetabolicprocessesorenzymeactivitiesassociatedonlywiththemicrobialcells.Conversely,whenratesofmetabolicprocesses,suchasrespiration,aremeasuredinthefield,thecontributionsoflivingrootsandanimalsaswellasmacro-scopicorganicdebrisarerecorded.Inotherwords,totalbiologicalratherthanmicrobiolog-icalactivitiesaremeasured(41).B.EnzymeActivities:MethodologyandInterpretationAccordingtothereviewbySkujins(40),Woodsin1899suggestedthatextracellularenzymescouldbepresentandactiveinsoil .The rstmeasurementsofenzymeactivitiesinsoilweredoneoncatalaseandperoxidaseactivitiesfrom1905to1910(40).Sincethen,theactivityofdozensofenzymeshasbeendetectedinsoil.Obviouslythenumberofenzymesisconsiderablygreaterthanthosemeasuredbecauseofthemultitudeofmicro-bial,faunal,andplantspeciesinhabitingsoil(46).Inaddition,theactivitymeasuredbymanyassayscannotbeascribedtotheactionofasingleenzyme.Thusdehydrogenaseactivityisdeterminedbythemultipleenzymereductionofasyntheticsubstrate(TTCorINT)duetoanoxidationofgenerallyunknownendogenoussubstrateswhoseconcentra-tionisalsounknown(46).Casein-hydrolyzingactivitiesaremeasuredwithoutspecificidentificationofthebondhydrolyzedorofallproductsformed.Itisimportanttoempha-sizethatevenwhenallthecomponentsofthereactionareknown,forexample,inthecaseofureaseassays,differentenzymesfromdifferentsources(microbial,plant,oranimalcells)catalyzethesamereaction.Tables 2and3 (99–105)reportarangeofactivitiesofenzymescommonlyinvesti-gated ... variable effects,depending on soil and enzyme assay conditions (46,120,162,1 63) . The kinetic analysis of the decline in the activity of l-histidine NH 3 -lyase duringa 96-h incubation period with ... effective for both L- and D- glutamic acid. The PLP-Cu2ϩ-smectitehas acted as a ‘‘pseudoenzyme’’ wherein the PLP was active and independent of the protein matrix of the enzyme and the silicate structure...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 2 pptx
... 0.80 35 .61 97190 59 .30 4. 53 13. 09 94Schleinsee1 1 .30 2.51 0.52 20 3 1.80 2.20 0.82 405 2.98 0.99 3. 01 857 161.51 0. 93 1 73. 67 989 297.60 2.08 1 43. 07 9612 32 7. 63 1 .30 252. 03 99APase, alkaline ... Inc.Currently,itisevidentthatmicroorganismsformcomplexmicrobialfoodwebsinallaquaticecosystems,andthattheiractivitiesandmetabolismsoftenaretightlycoupled and/ ormutuallyaffected( 132 ,1 43, 144).Therefore,itisnotsurprisingthatenzymaticpropertiesandactivitiesofdifferentcomponentscreatingthemicrobialfoodwebsinlakeecosystemshavedemonstratedcloserelationships.Severalreportshavedocumentedthestrongdependencyofbacterialsecondaryproductiononectoenzymeactivitiesofaquaticmicroorganisms(2–4,16,17,19,25,28,29 ,33 ,36 ,59).Thereoftenisasignificantcorrelationbetweenphytoplanktonprimaryproductionandactivitiesofdifferentectoenzymesinfreshwaterecosystems(25,28,29 ,33 ,52).Ourstudiesinlakesofdifferingdegreesofeutrophicationhaveshownmicrobialesteraseactivitytobepositivelycorrelatedtophytoplanktonprimaryproduction,bacterialsecondaryproduction,andconcentrationofdissolvedorganiccarbon(DOC)(Fig. 13) .Wehavefoundasignificantnegativerelationshipbetweenenzymeactivityandtheper-centageofphytoplanktonextracellularrelease(PER)ofphotosyntheticorganiccarboninthestudiedlakes.ThisnegativecorrelationbetweenPERandesteraseactivityindicatedthatenzymesynthesiswaspartiallyinhibitedinbacteriabylow-molecular-weightphoto-syntheticproductsofphytoplanktonthatwerereadilyutilizedbythesemicroheterotrophs:i.e.,catabolicrepressionofesterasesynthesiswasfoundinlakescharacterizedbyhighPERofphytoplankton(29 ,33 ).VIII.ECTOENZYMEACTIVITYANDLAKEWATEREUTROPHICATIONTheimportanceoforganicmatterasavariableforevaluatingthetrophicstatusoflakeshasbeenrecognizedsincethebeginningofthe20thcentury(145,146).Increasingconcen-trationsoforganicconstituentsinwaterarethedistinctindicatorsofacceleratedeutrophi-cationprocessesinmanylakes(147–149).OurstudiesclearlydemonstratedthatenzymeactivitiesweresignificantlypositivelyproportionaltoDOCcontentoflakes(Fig.13C).Asdescribedearlierinthischapter,severalmicrobialectoenzymesareresponsibleforrapidtransformationanddegradationofbothdissolvedorganicmatterandPOMinfresh-waterecosystems.Therefore,wehypothesizethatan‘‘enzymaticapproach’’canbeveryusefulinthestudiesoflakeeutrophication.Severalreportspointedoutthatmicrobialenzymaticactivitieswerecloselyrelatedtotheindicesofwatereutrophicationand/orthetrophicstatusofaquaticecosystems(25,27,29 ,31 ,33 ,38 ,52,58,62,78).Ourstudiesalongthetrophicgradientoflakes(fromoligo/mesotrophictohypereutrophiclakes[Fig.14A]supportourhypothesis(andtheassumptionsofothers)thatselectedenzymaticmicrobialactivitiesareverypracticalforarapidrecognitionofthecurrenttrophicstatusoflakes.Activitiesofalkalinephosphatase,esterase,andaminopeptidaseincreasedexponentiallyalongatrophicgradientandcorre-latedsignificantlywiththetrophicstateindexofthestudiedlakes(Fig.14B,C,D).Wealsofoundastrongrelationshipbetweenactivitiesofectoenzymesandphytoplanktonprimaryproductionintheselakes.RapidincreasesinectoenzymeactivitieswereobservedespeciallyinarangeofgraduallyeutrophiclakeswhenthevalueofCarlson’strophicstateindex(TSI)wasabove55(150)(Fig.14).Moreover, ... the cyto-plasmic membrane, where they hydrolyze macromolecules in close vicinity to the cell. The resulting low-molecular-weight products are then transported across the cell mem-brane and utilized...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 4 potx
... Inc.Althoughthisstudyinvolvedtheuseofageneticallymodifiedmicrobe,themodi - cationswerenotintendedtohaveafunctionalimpact;theywereinsertedasgeneticmark-ers.Asecondstudycomparingtheeffectofthesamegeneticallymarkedstraintothatofafunctionallymodifiedstrainshowedeffectsthataremoreinteresting (36 ).Theaimofthisworkwastodeterminetheimpactintherhizosphereofwildtypealongwithfunction-allyandnonfunctionallymodifiedPseudomonasfluorescensstrains.Thewild-typeF1 13 straincarriedageneencodingtheproductionoftheantibiotic2,4-diacetylphloroglucinol(DAPG),usefulinplantdiseasecontrol,andwasmarkedwithalacZYgenecassette .The firstmodifiedstrainwasafunctionalmodificationofstrainF113withrepressedproductionofDAPG,creatingtheDAPGnegativestrainF113G22.Thesecondpairedcomparisonwasanonfunctionalmodificationofwild-type(unmarked)strainSBW25,constructedtocarrymarkergenesonly,creatingstrainSBW25EeZY-6KX.Significantperturbationswererecordedintheindigenousbacterialpopulationstruc-ture;theF1 13( DAPGϩ)straincausedashifttowardslower-growingcolonies(Kstrate-gists)comparedwiththenon-antibiotic-producingderivative(F113G22)andSBW25strains.TheDAPGϩstrainalsosignificantlyreduced,incomparisonwiththoseoftheotherinocula,thetotalPseudomonassp.populations,butdidnotaffectthetotalmicrobialpopulations.ThesurvivalofF113andF113G22wasanorderofmagnitudelowerthanthatoftheSBW25strains.TheDAPGϩstraincausedasignificantdecreaseintheshoot-to-rootratioincomparisontothatofthecontrolandotherinoculants,indicatingplantstress.F113increasedsoilalkalinephosphatase,phosphodiesterase,andarylsulfataseac-tivities(Table2)comparedtothoseofthecontrols.Theotherinoculareducedthesameenzyme ... would in- crease the microbial P demand.Inverse trends were found with the C and N cycle enzymes in comparison to the general trend found in the P and S cycle enzymes. The F1 13 (DAPGϩ) strain was ... found in the Vmax(74% in the grasslandCopyright © 2002 Marcel Dekker, Inc.solublecarbohydratesandthetotalwater-solublecarbonintherhizospheresoil(Table 3) .StrainF113significantlyincreasedthesoilproteincontentrelativetothatofthecontrolbutnotinrelationtotheF113G22treatment.TheF113treatmenthadasignificantlygreaterorganicacidcontentthanthecontrolandF113G22treatments;theF113G22treatmentalsohadsignificantlygreatercontentthanthecontrol.Bothinocularesultedinsignificantlylowerphosphatecontentthanthecontrol.Bothinoculaincreasedcarbonavailability;however,antibioticproductionbystrainF113reducedtheutilizationofor-ganicacidsreleasedfromtheplant,resultingindifferingeffectsofthetwostrainsonnutrientavailability,plantgrowth,soilenzymeactivities,andPseudomonassp.popula-tions.Thesestudieshighlighttheimportanceoftheuseofsoilenzymeactivitiesinimpactstudies.Theyalsoillustratehowthecombinationofanumberofenzymaticmeasurementsfromdifferentnutrientcyclescanbeusedasadiagnostictooloftheprocessesinvolvedinsuchperturbations.Theenzymaticmethodsworkedwellinsmallmicrocosmsandlargeintactsoilcoreswhereenvironmentalvariationisminimized;thesamemethodsthenweretestedinfieldscaletrialsoftheF113strain.SoilenzymeactivitieswereusedtoinvestigatetheimpactofstrainF113intherhizosphereoffield-grownsugarbeet(42).Thereweredistincttrendsinrhizosphereen-zymeactivitiesinrelationtosoilchemicalcharacteristics(measuredbyelectroultrafiltra-tion).Forexample,theactivitiesofenzymesfromthephosphoruscycle(acidphosphatase,alkalinephosphatase,andphosphodiesterase)andofarylsulfatasewerenegativelycorre-latedwiththeamountofreadilyavailableP(Table4),whereasureaseactivitywasposi-tively...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 5 ppt
... short-chain poly-P was higher in the internal hyphae (67). Long-chain poly-P seems to be more efficient in transporting Pi from the extraradical to the intraradical part of the fungi. Activity of enzymes ... Marcel Dekker, Inc.ThepatternsofenzymeactivityandmRNAaccumulationsuggestthatchitinases and -1 , 3- glucanasesmightbepartoftheearlydefenseresponsebytheplanttotheinvad-ingfungus,whichisthensuppressedassymbioticinteractionsdevelop.Inthiscontext,planthydrolasesmaybeinvolvedintheregulationofAMdevelopment.Nevertheless,someexperimentaldatarevealedthatitisnotlikelythatplantchitinasesandglucanasesareessentialtothecontrolofthegrowthofAMfungi.TransgenicplantsconstitutivelyexpressinghighlevelsofdifferentacidicformsoftobaccoPRs(includingchitinasesand -1 , 3- glucanases)becamenormallycolonizedbytheAMfungi(122,1 23) .Thefactthatchitinasesand -1 , 3- glucanasesinducedbytheAMsymbioticfungiorbyconstitutivegeneexpression,donotpreventrootcolonizationsuggeststhattheyareineffectiveincontrollingfungaldevelopment.ThelowenzymaticaffinityforAMfungalcomponentsorinaccessibilityoftheseenzymestofungalcellwallcomponentsmaycausethisineffec-tiveness(112).Conversely,specificacidicformsofchitinaseand -1 , 3- glucanaseareactivatedinseveralplantscolonizedbyAMfungi.Thesesymbiotic,specificisoenzymeshavebeenreportedinpea(124),tobacco(118),andtomato(125–127)rootsandaredifferentfrompathogen-inducedisoformsorconstitutiveenzymes.Inaddition,newchitosanaseisoformshavebeenshowninpea(128)andtomato(126).Chitosanasesarehydrolyticenzymesactingonchitosan,aderivativepartiallyorfullydeacetylatedofchitin(129).Interestingly,themycorrhizal-relatedchitinaseisoformdescribedintomato-colonizedrootsappearedtodisplaychitosanaseactivity.Thisbifunctionalcharacterwasnotfoundfortheconstitutive enzymes, orinPhytophthorasp.–inducedchitinases(126).Mycorrhizal-specificplantchi-tinasesarenotactiveinpathogen-infectedroots(118,124–125)orinRhizobiumsp.legumesymbiosis( 130 ),indicatingadifferentialinductionandfunction.AlthoughtheprecisefunctionofplanthydrolaseactivitiesintheestablishmentofAMsymbioticinteractionisstillunclear,theirstimulationseemstobeakeypointinthemechanismofrecognitionandsignalingbetweenplantrootsandAMfungi.AregulatoryroleoftheseenzymesduringestablishmentofAMandotherrootsymbiosishasbeenproposed.Stimulationofspecificplantchitinaseshasbeenreportedinsoybean/Rhizobiumsp.( 131 )andectomycorrhiza( 132 ).Ithasbeenpostulatedthatchitinasesmaybeinvolvedintherecognitionoftherhizobialnodulationsignalsand,thus,intheregulationofthenodulationprocess( 133 ).Thedatasuggestaspecificrolefortheseenzymes,onethatcouldberelatedintheAMsymbiosistothedetection,modification ,and/ orreleaseofchitinorchitosanoligomersfromthefungalcellwallthatcanactassignalingcompoundsduringthedevelopmentofAM(Fig .3) .Inthisprocessofsignalexchange,themodulationof ... Inc.ThepatternsofenzymeactivityandmRNAaccumulationsuggestthatchitinases and -1 , 3- glucanasesmightbepartoftheearlydefenseresponsebytheplanttotheinvad-ingfungus,whichisthensuppressedassymbioticinteractionsdevelop.Inthiscontext,planthydrolasesmaybeinvolvedintheregulationofAMdevelopment.Nevertheless,someexperimentaldatarevealedthatitisnotlikelythatplantchitinasesandglucanasesareessentialtothecontrolofthegrowthofAMfungi.TransgenicplantsconstitutivelyexpressinghighlevelsofdifferentacidicformsoftobaccoPRs(includingchitinasesand -1 , 3- glucanases)becamenormallycolonizedbytheAMfungi(122,1 23) .Thefactthatchitinasesand -1 , 3- glucanasesinducedbytheAMsymbioticfungiorbyconstitutivegeneexpression,donotpreventrootcolonizationsuggeststhattheyareineffectiveincontrollingfungaldevelopment.ThelowenzymaticaffinityforAMfungalcomponentsorinaccessibilityoftheseenzymestofungalcellwallcomponentsmaycausethisineffec-tiveness(112).Conversely,specificacidicformsofchitinaseand -1 , 3- glucanaseareactivatedinseveralplantscolonizedbyAMfungi.Thesesymbiotic,specificisoenzymeshavebeenreportedinpea(124),tobacco(118),andtomato(125–127)rootsandaredifferentfrompathogen-inducedisoformsorconstitutiveenzymes.Inaddition,newchitosanaseisoformshavebeenshowninpea(128)andtomato(126).Chitosanasesarehydrolyticenzymesactingonchitosan,aderivativepartiallyorfullydeacetylatedofchitin(129).Interestingly,themycorrhizal-relatedchitinaseisoformdescribedintomato-colonizedrootsappearedtodisplaychitosanaseactivity.Thisbifunctionalcharacterwasnotfoundfortheconstitutive enzymes, orinPhytophthorasp.–inducedchitinases(126).Mycorrhizal-specificplantchi-tinasesarenotactiveinpathogen-infectedroots(118,124–125)orinRhizobiumsp.legumesymbiosis( 130 ),indicatingadifferentialinductionandfunction.AlthoughtheprecisefunctionofplanthydrolaseactivitiesintheestablishmentofAMsymbioticinteractionisstillunclear,theirstimulationseemstobeakeypointinthemechanismofrecognitionandsignalingbetweenplantrootsandAMfungi.AregulatoryroleoftheseenzymesduringestablishmentofAMandotherrootsymbiosishasbeenproposed.Stimulationofspecificplantchitinaseshasbeenreportedinsoybean/Rhizobiumsp.( 131 )andectomycorrhiza( 132 ).Ithasbeenpostulatedthatchitinasesmaybeinvolvedintherecognitionoftherhizobialnodulationsignalsand,thus,intheregulationofthenodulationprocess( 133 ).Thedatasuggestaspecificrolefortheseenzymes,onethatcouldberelatedintheAMsymbiosistothedetection,modification ,and/ orreleaseofchitinorchitosanoligomersfromthefungalcellwallthatcanactassignalingcompoundsduringthedevelopmentofAM(Fig .3) .Inthisprocessofsignalexchange,themodulationof...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 8 potx
... affecting the efficiency of interaction of the substrate and enzyme molecules. In other words, a portion of the enzyme molecules existing in the field soil may not be actively engaged in catalyzing their ... transforma-tions include the effect of bonding of β-d-glucosidase to a phenolic copolymer of l-tyro-sine, pyrogallol, or resorcinol (108) and of linking of urease to tannic acid (49,52). Sarkar and ... Distribution of L-histidine ammonia-lyase activity in soils. Soil Sci 136 :34 7 35 3, 19 83. 46. WT Frankenberger Jr, MA Tabatabai. Factors affecting L-glutaminase activity in soils. SoilBiol Biochem 23: 875–879,...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 9 potx
... that the prominence of ligninase-producing basidiomycetes (35 ) in terrestrial systems and pectinase-producing hyphomy-cetes (7,89) in aquatic systems probably affects the functional profile and ... activity and secondary production in free-living and marine-snow-associated bacteria. Mar Biol 1 13: 341 34 7, 1992. 34 . TK Kirk, RL Farrell. Enzymatic ‘‘combustion’’: The microbial degradation of lignin. ... of POM (Ͼ1 mm and 0.0 63 0.5 mm) were collected from each site and placed in litter bags. In using the ap-proach of Sinsabaugh et al. ( 73) and Jackson et al. (29), confined and in situ POM sampleswere...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 10 docx
... the years; these include vanilin, indulin, ferrulic acid, and, most importantly,14C-labeled synthetic lignins. Various fungal enzymes are involved in lignin degradation, including lignin peroxidase, ... wasconcluded that the higher levels of these enzymes in the upper part of the profile couldbe due to the presence of fungi (chitin in the cell walls) and arthropods (chitin in the exoskeleton) serving as ... strains and the extrac-tion of enzymes, provide complementary information on enzyme production by emphasi-zing the potential of the living hyphae and the sum of past and present activities re-spectively....
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 11 ppsx
... Inc.possibletofindseveralexplanationstointerpretaproteinadsorptionisotherm,withnoexperimentalevidenceavailabletochooseamongthem.TheadvantageoftheNMRmethodisthatitsimultaneouslygivesthequantityofadsorbedprotein,thesurfacecover-ageofthesolidbytheprotein,andthemonolayerormultilayermodeofadsorption(16).Onlyknowledgeofthesethreefactorsallowsapossibleunfoldingoftheproteinsontheclaysurfacestobedetectedandquantified.1.NuclearMagneticResonanceDetectionoftheExchangeofaParamagneticCationonProteinAdsorptiononClaysTheprincipleofthemethod(16)isbasedonthefactthattheadsorptionofproteinsonclayscausesthereleaseofcharge-compensatingcations(7,17).ItalsousesthesensitivityoftherelaxationtimesT1andT2ofnuclearspinstoparamagneticcationsinNMRspectros-copy(18,19).Asmallquantity(between 3and2 0µMdependingonthepH)ofaparamagneticcation,Mn2ϩ,isaddedtoasodium-saturatedmontmorillonitesuspension(1gLϪ1)witha10-mMconcentrationoforthophosphate.Thesuspensionisstudiedby 31 PNMRspec-troscopy.Aninterestingphenomenonisobserved:(1)theMn2ϩcationsthatareadsorbedontheclaysurfacedonotinteractatallwiththeorthophosphate,asshownbythecompari-sonbetweentheclaysuspensionandsupernatantafterremovaloftheclaybycentrifuga-tion ;and( 2)theMn2ϩcationsinsolutioninteractwiththeorthophosphate,leadingtoalinearincreaseofthelinewidthathalfheight,∆ν1/2,oftheorthophosphatepeakontheNMRspectrum.Thislasteffectistheresultoftheparamagneticcontributiontothede-creaseofthespin–spinrelaxationtime,T2,oftheorthophosphatesignal.Whenagivenquantityofproteinisintroducedintothissuspension,itdisturbstheequilibriumbetweentheparamagneticMn2ϩadsorbedontheclaysurfaceandthatinsolution.Theanalysisoftheresultinglinewidthoftheorthophosphosphatesignalgivesthequantityofcationsexchangedonadsorption.Witha300-MHzNMRspectrometer,themeasurementtakesafewminutes;witha500-MHzspectrometer,1minissufficient(evenlessifhigherconcentrationsofortho-phosphateareused).Asnocentrifugationisrequiredwiththismethod,thisshorttimeofsignalacquisitioniscompatiblewithkineticstudies.Theresultsareexpressedas∆νP,whichisthedifferencebetween∆ν1/2inthesystemwithparamagneticcationsand∆ν1/2inacontrolofthesamecomposition,(butwithoutparamagneticcations)dividedbytheconcentrationofparamagneticcations.ThesurfacecoverageoftheclaybytheproteincanbededucedfromthefractionofMn2ϩreleased.Theknowledgeofboththequantityofproteinadsorbedandthesurfacecoverageofthesolidallowsthecalculationoftheinterfacialareaofcontactbetweenasingleproteinmoleculeandtheclaysurfaceatdiffer-entpHandionicstrengths.2.ConformationalChangesonAdsorptionofaSoftProtein,BovineSerumAlbumina.DescriptionoftheProgressiveSurfaceCoverageoftheClayFigure1shows the ... (2) a possi-ble unfolding of the protein on the surface changing the interfacial area between individualprotein and surface and the quantity of protein adsorbed at saturation; (3) the surfacecoverage ... contrast to the three preceding models, which assume that the enzymes retain the sameconformation in the adsorbed state and in solution, another model is based on a pH-depen-dent unfolding of the enzyme...
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Enzymes in the Environment: Activity, Ecology and Applications - Chapter 12 ppsx
... systems, lasR-lasI and rhlR-rhlI. The lasI and rhlI gene productsare involved in the synthesis of two different AHL molecules, N- ( 3- oxododecanoyl)-l-homoserine lactone and N-buytryl-l-homoserine lactone, ... components in- clude β-galactosidase, β-N-acetylglucosaminidase, β-N-acetylgalactosaminidase, - and β-mannosidase, and α-fucosidase (116). Other bacteria then produce proteolytic enzymes, such ... Inc.Microbialmatsareexamplesofthicklylayeredbiofilmsofphotosyntheticmicro-organismsattachedtorocksandsedimentparticlesinaqueoushabitats(25).Theyareoftenfoundunderextremeenvironmentalconditions.Forexample,inthevicinityofdeepseahydrothermalvents,microorganismswithinbiofilmssurviveextremetemperatures(86,87).HotspringsareanotherextremehabitatwherebothhightemperaturesandsulfideconcentrationsharbormatscontaininglayersprimarilycomposedofArchaea,includingsulfate-reducingpurplebacteria(e.g.,Chloroflexisspp.,Chromatiumspp.,Thiopediaro-seopersicinia)inassociationwithcyanobacteria(25).Additionalextremeenvironmentswheremicrobialmatsmaybefoundincludehypersalinelakes(88),terrestrialdesertswithcyclicaldroughtanddesiccation,sodalakesandacidthermalwaterscontainingextremepHconditions,andregionswithhighlevelsofultraviolet(UV)irradiation(88).Themicro-bialspeciesthatarefoundintheseextremeenvironmentsarelimitedtoprimarilycyano-bacteria(e.g.,OscillatoriaandSpirulinaspp.)andotherssuchasDesulfovibriospp.,Beg-giatoaspp.,andThiovulumspp.,withdifferingandvaryingdegreesoftolerance(89).Althoughmatsareprimarilycomposedofprokaryotes,otherorganisms,suchastheeukar-yoticCyanidiumsp.,havebeenfoundatpHlevelsbelow4.5(89).Studieshaveshownthatmostoftheorganismswithinamatareoftennotphysiologicallyadaptedtotheextremeenvironmentbutgrowthwithinlayersofathickbiofilmhelpsthemsurviveandfindasuitablemicroniche(89).Microbialmatsareagoodexampleoftheprotectivenatureofbiofilmgrowthandthemethodwithwhichstratificationcanencouragenutrientavailabilityandcycling(90).Biofilmshavebeenobservedatotheraquaticinterfacesbesidesthoseatasolid–liquidinterface.Forexample,instagnantwaters,biofilmsaresometimesfoundattheair–liquidinterfaceandareoftenseenasbrownorgreenlayerscomposedofalgaeandotheraquaticmicroorganisms.Anotherexampleisthewaxytypebiofilmattheair–liquidinter-faceformedfromtherugosephenotypeofVibriocholeraeisolatedfromstarvationme-dium(91).Theinterfacebetweenjetfuelsandwatercanalsoharborbiofilmgrowth,suchasthefungusCladosporiumresinae(92).VII.NONAQUATICENVIRONMENTSAlthoughbiofilmshaveoftenbeenstudiedinaquaticenvironments,morerecentstudieshaveshownthatmicroorganismswithinthickEPSmatricesorbiofilmsarealsofoundinnonaquaticenvironmentssuchastherhizosphere (Chapter4 ),soil,andsubsurfaceenviron-ments( 93, 94).Oneofthemorecomplexenvironmentsisthesoilecosystem,withitsmanydifferentparticlesandporespaces(95).Microorganismsinthesoiladheretosurfacessuchasinorganicsolidparticles,humicmatter,plantmaterial(roots),andmicrofauna.Plantsprovidelargeamountsofcarbonandothernutrientstoencouragemicrobialgrowthinthevicinityoftheroots ,and, inturn,themicroorganismsfixnitrogen,assisttheplantinadsorptionofnutrientsfromthesoil,andprotecttherootsagainstpathogens.Anotherexampleofanonaquaticbiofilmisthecolonizationoftheleavesofplants—thephyllo-sphere(96 ;Chapter6 ).Thesebiofilmsconsistofadiversepopulationofmicroorganisms,including...
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Từ khóa: enzymes in the manufacturethe dictionary of ecology and environmental scienceproduction networks in the asiapacific region facts and policy implicationsrules in the formation of plural and possessive nounsunit 6 the environment getting started and listen and readBáo cáo thực tập tại nhà thuốc tại Thành phố Hồ Chí Minh năm 2018Nghiên cứu sự biến đổi một số cytokin ở bệnh nhân xơ cứng bì hệ thốngNghiên cứu sự hình thành lớp bảo vệ và khả năng chống ăn mòn của thép bền thời tiết trong điều kiện khí hậu nhiệt đới việt namNghiên cứu vật liệu biến hóa (metamaterials) hấp thụ sóng điện tử ở vùng tần số THzNghiên cứu tổ chức chạy tàu hàng cố định theo thời gian trên đường sắt việt namGiáo án Sinh học 11 bài 13: Thực hành phát hiện diệp lục và carôtenôitGiáo án Sinh học 11 bài 13: Thực hành phát hiện diệp lục và carôtenôitĐỒ ÁN NGHIÊN CỨU CÔNG NGHỆ KẾT NỐI VÔ TUYẾN CỰ LY XA, CÔNG SUẤT THẤP LPWANĐỒ ÁN NGHIÊN CỨU CÔNG NGHỆ KẾT NỐI VÔ TUYẾN CỰ LY XA, CÔNG SUẤT THẤP LPWANNGHIÊN CỨU CÔNG NGHỆ KẾT NỐI VÔ TUYẾN CỰ LY XA, CÔNG SUẤT THẤP LPWAN SLIDETrả hồ sơ điều tra bổ sung đối với các tội xâm phạm sở hữu có tính chất chiếm đoạt theo pháp luật Tố tụng hình sự Việt Nam từ thực tiễn thành phố Hồ Chí Minh (Luận văn thạc sĩ)Phát triển du lịch bền vững trên cơ sở bảo vệ môi trường tự nhiên vịnh hạ longNghiên cứu về mô hình thống kê học sâu và ứng dụng trong nhận dạng chữ viết tay hạn chếTìm hiểu công cụ đánh giá hệ thống đảm bảo an toàn hệ thống thông tinTổ chức và hoạt động của Phòng Tư pháp từ thực tiễn tỉnh Phú Thọ (Luận văn thạc sĩ)Giáo án Sinh học 11 bài 14: Thực hành phát hiện hô hấp ở thực vậtGiáo án Sinh học 11 bài 14: Thực hành phát hiện hô hấp ở thực vậtChiến lược marketing tại ngân hàng Agribank chi nhánh Sài Gòn từ 2013-2015MÔN TRUYỀN THÔNG MARKETING TÍCH HỢPQUẢN LÝ VÀ TÁI CHẾ NHỰA Ở HOA KỲ