Freefattyacidsareusefulassourcematerialsfor
theproductionofbiodieselfuelandvarious
chemicalssuchaspharmaceuticalsanddietary
supplements.Previously,weattaineda9.2-fold
increaseinfreefattyacidproductivitybydisrupting
apredictedacyl-CoAsynthetasegene(faaA,
AO090011000642)inAspergillusoryzae.Inthis
study,weachievedfurtherincreaseintheproductiv-
itybyoverexpressingapredictedtransketolasegene
ofthepentosephosphatepathwayinthefaaAdis-
ruptant.TheA.oryzaegenomeispredictedtohave
threetransketolasegenesandoverexpressionof
AO090023000345,oneofthethreegenes,resultedin
phenotypicchangeandfurtherincrease(corre-
spondingtoanincreasedproductionof0.38mmol/g
drycellweight)infreefattyacidsat1.4-fold
comparedtothefaaAdisruptant.Additionally,the
biomassofhyphaeincreasedat1.2-foldbytheover-
expression.Asaresult,freefattyacidproduction
yieldperliterofliquidcultureincreasedat1.7-fold
bytheoverexpression.
Keywords:transketolasegeneoverexpression;
pentosephosphatepathway;freefatty
acid;productivity;Aspergillusoryzae
faaAdisruptant
Involvedintheincreasingglobaldemandoffossil
fuels,biofuelsgeneratedfromplantbiomasshavesig-
nificantlybeenfocusedduetolesseffectonglobal
environmentinthecarbonneutralcharacteristics.1,2)In
addition,somepharmaceuticalsanddietarysupple-
mentsproducedfromrarenaturalresourcesareexpen-
sive,andtheirproductionbytheheterologous
microbialbiosynthesisforloweringthepriceshasbeen
desired.3,4)
Microbiallipidproductionhasbeenresearchedin
cerevisiae,8−10)Yarrowialipolytica,11)etc.),filamentous
fattyacid(FFA),acylglycerol,fattyacidmethylester,
andalkanehavebeenthemajortargetsofthemicrobial
production.1)Amongthem,FFAcanbeusedassource
materialsofbiodieselfuelsandchemicals.1)
ThefilamentousfungusA.oryzaeiswellknownfor
highproductioncapabilityofhydrolasessuchasamy-
lase,protease,andlipase.17)Inaddition,A.oryzaeis
notonlyaproducerofsmallmoleculessuchasthe
kojicacid,18)butalsolistedasasafemicroorganism
fortheGRAS(i.e.GenerallyRecognizedasSafe)sta-
tusbytheUSFoodandDrugAdministration.19)Thus,
itimpliesA.oryzaeissuperiortotheotherfilamentous
fungiintheproductionofawiderangeofbiomole-
culesforindustrialapplication.Infact,ithasbeenused
forproducingsake(ricewine),shoyu(soysauce),and
miso(soybeanpaste)byconvertingstarch,proteins,
andlipidsderivedfromrice,wheat,andsoybean,to
manyvarietiesofsmallmoleculesthroughthecatabo-
lismandtheassimilation.
Inourresearch,A.oryzaehasbeenusedforaccom-
plishinghighproductionoflipidssuchasFFAand
acylglycerolassourcematerialsofbiofuelsandchemi-
cals.12,13)Todate,overexpressionofafattyacidsyn-
thase(FAS)geneinvolvedinthedenovofattyacid
biosynthesisenhancedtheFFAproductivityat2.1-
fold.12)Disruptionofanacyl-CoAsynthetasegene
faaAalsodrasticallyincreasedtheFFAproductivityat
9.2-fold.13)However,constructionofadoublemutant
havingboththeFASoverexpressionandthefaaAdis-
ruptionhasbeendifficultforunknownreasonandbeen
underconstruction.
Thepentosephosphatepathway(PPP)existscom-
monlyinabroadrangeoforganismsandgenerates
bothNADPHandpentosemolecules.Itbeginswith
theglucose6-phosphatemoleculesynthesizedatthe
firstreactionstepofglycolysis,thusPPPcompetesthe
usewiththeglycolysis.PPPconsistsofsevenreaction
stepsuntilitfinallymergesintoglycolysisagain
Freefattyacidsareusefulassourcematerialsfortheproductionofbiodieselfuelandvariouschemicalssuchaspharmaceuticalsanddietary补充剂。以前,weattaineda9.2 折increaseinfreefattyacidproductivitybydisruptingapredictedacyl-CoAsynthetasegene(faaA,AO090011000642)inAspergillusoryzae.Inthis研究中,weachievedfurtherincreaseintheproductiv-itybyoverexpressingapredictedtransketolasegeneofthepentosephosphatepathwayinthefaaAdis-ruptant。TheA.oryzaegenomeispredictedtohavethreetransketolasegenesandoverexpressionofAO090023000345,oneofthethreegenes,resultedinphenotypicchangeandfurtherincrease(corre-spondingtoanincreasedproductionof0.38mmol/gdrycellweight) infreefattyacidsat1.4 折comparedtothefaaAdisruptant.Additionally,thebiomassofhyphaeincreasedat1.2-foldbytheover-表达式。因此 freefattyacidproductionyieldperliterofliquidcultureincreasedat1.7 折bytheoverexpression。关键词︰ transketolasegeneoverexpression;pentosephosphatepathway; freefatty酸; 生产力;AspergillusoryzaefaaAdisruptantInvolvedintheincreasingglobaldemandoffossil燃料,biofuelsgeneratedfromplantbiomasshavesig.nificantlybeenfocusedduetolesseffectonglobalenvironmentinthecarbonneutralcharacteristics.1,2)In另外,somepharmaceuticalsanddietarysupple-mentsproducedfromrarenaturalresourcesareexpen-平整、 andtheirproductionbytheheterologousmicrobialbiosynthesisforloweringthepriceshasbeendesired.3,4)Microbiallipidproductionhasbeenresearchedin酵母,8−10) Yarrowialipolytica,11) 等)、 丝状指出 (FFA),甘,fattyacidmethylester,andalkanehavebeenthemajortargetsofthemicrobialproduction.1)Amongthem,FFAcanbeusedassourcematerialsofbiodieselfuelsandchemicals.1)ThefilamentousfungusA.oryzaeiswellknownforhighproductioncapabilityofhydrolasessuchasamy-lase,protease,andlipase.17)Inaddition,A.oryzaeisnotonlyaproducerofsmallmoleculessuchasthekojicacid,18) butalsolistedasasafemicroorganismfortheGRAS (i.e.GenerallyRecognizedasSafe) sta-tusbytheUSFoodandDrugAdministration.19)Thus,itimpliesA.oryzaeissuperiortotheotherfilamentousfungiintheproductionofawiderangeofbiomole-culesforindustrialapplication。事实上 ithasbeenusedforproducingsake (米酒),酱油 (酱油),和味噌 (soybeanpaste) byconvertingstarch,蛋白质,andlipidsderivedfromrice,小麦,andsoybean,到manyvarietiesofsmallmoleculesthroughthecatabo-lismandtheassimilation。Inourresearch,A.oryzaehasbeenusedforaccom-plishinghighproductionoflipidssuchasFFAandacylglycerolassourcematerialsofbiofuelsandchemi-cals.12,13)Todate,overexpressionofafattyacidsyn-这些 (FAS) geneinvolvedinthedenovofattyacidbiosynthesisenhancedtheFFAproductivityat2.1-fold.12) Disruptionofanacyl CoAsynthetasegenefaaAalsodrasticallyincreasedtheFFAproductivityat9.2 fold.13) 然而,constructionofadoublemutanthavingboththeFASoverexpressionandthefaaAdis-ruptionhasbeendifficultforunknownreasonandbeen建设。Thepentosephosphatepathway (PPP) existscom-monlyinabroadrangeoforganismsandgeneratesbothNADPHandpentosemolecules.Itbeginswiththeglucose6-phosphatemoleculesynthesizedatthefirstreactionstepofglycolysis thusPPPcompetestheusewiththeglycolysis。PPPconsistsofsevenreactionstepsuntilitfinallymergesintoglycolysisagain
正在翻譯中..