《食品微生物学》真核微生物的形态结构和功能95

食品微生物学Morphology，structureandphysiologicalfunctionofeukaryotesDefinition：eukaryoticcellsarecompartmentalizedbymembran-es.Thecellcontainsseveraldifferenttypesofmembranebou-ndorganelleinwhichdifferentbiochemicalandphysiologicalprocessescanoccurinaregulatedway.

Membranesalsotransportinformation，metabolicintermediatsandend-productsfromthesiteofbiosynthesistothesiteofuse.Eukaryotesisabiggroupoflivingorganismsmadeupofeukaryoticmembraneboundnucleusandseveralorganellessuchasmitochondriondividedbymitosis.真核生物是一大类细胞核具有核膜，能进行有丝分裂，细胞质中存在线粒体或同时存在叶绿体等多种细胞器的生物.

eukaryoticmicro-organismsisagroupofMicroorganismsthatmadeupofeukaryoticcellsincludeFungi、microalgae（）、andprotozoa真核细胞真核生物

真核微生物peroxisomesmitochondrioncytosolchloroplastSmoothendoplasmicreticulumStructureofatypicalplantcellCytosol细胞液PlasmamembraneSecretoryvesiclesStructureofatypicalanimalcellmembraneCellwall

mitochondrionVesicals

(泡囊)

Dictyosomes(分散高尔基体)HyphalstructuresEndoplasmicreticlumribosomesmembranevacuoleCellwallmitochondrionNucleusEndoplasmicreticulumYeaststructuresYeaststructures

真核微生物主要包括菌物界(Mycetalia或广义的“Fungi”)中的真菌(Eumycota或狭义的“Fungi”，即TrueFungi)、粘菌(Myxomycota或Fungi—likeProtozoa)、假菌(Chromista或Pseudofungi)，植物界(Plantae)中的显微藻类(Algae)和动物界(Animalia)中的原生动物(Protozoa)

Majorgroupsofeukaryoticmicroorganisms

真核微生物的主要类群

植物界（plantae）：显微藻类algae

动物界（animalia）：原生动物protozoa真核微生物

黏菌myxomycota假菌pseudofungi菌物界（mycetalia）单细胞真菌unicellularfungi真菌eumycota丝状真菌filamentous大型子实体蕈菌mushroomMajorgroupsofeukaryoticmicroorganismsEukaryoticmicroorganisms“菌物界’’这个名词是我国学者裘维蕃等于1990年提出的，并已·得到学术界的一定支持，这是指与动物界、植物界相并列的一大群无叶绿素、依靠细胞表面吸收有机养料、细胞壁一般含有几丁质的真核微生物。一般包括真菌、粘菌和假菌(卵菌等)3类。真菌是最重要的真核微生物，故是本章的重点，它们的特点是：①无叶绿素，不能进行光合作用；②一般具有发达的菌丝体；③细胞壁多数含几丁质；④营养方式为异养吸收型；⑤以产生大量无性和(或)有性孢子的方式进行繁殖；⑥陆生性较强

Fungiarefilamentous,non-photosynthetic,eukaryoticmicroorganismsthathaveaheterotrophicnutrition.Theirbasiccellularunitisdescribedasahypha.Thisisatubularcellwhichissurroundedbyarigid,chitin-containingcellwall.Thehyphaextendsbytipgrowth,andmultipliesbybranching,creatingafinenetworkcalledamycelium.Hyphaecontainnuclei,mitochondria,ribosomes,Golgiandmembrane-boundvesicleswithinaplasma-membraneboundcytoplasm.Thesubcellularstructuresaresupportedandorganizedbymicrotubulesandendoplasmicreticulum.Thecytoplasmiccontentsofthehyphatendtobeconcentratedtowardsthegrowingtip.Olderpartsofthehyphaareheavilyvacuolatedandmaybeseparatedfromtheyoungerareasbycrosswallscalledseptae.Notallfungiaremulticellular,someareunicellularandaretermedyeasts.Thesegrowbybinaryfissionorbudding,creatingnewindividualsfromtheparentcell.Mould（Mold）

DefinitionMoldarefilamentous,nonphotosynthetic,eukaryoticmicroorganismsthathaveaheterotrophicnutrition（filamentousfungi）。

MorphologyandstructureHyphaandmycelium菌丝与菌丝体lowerfungi——non-septatemyceliumshigherfungi——septatemyceliumwithelaborate、perforateseptaThehyphaextendsbytipgrowth,andmultipliesbybranching,creatingafinenetworkcalledamycelium.

（pluralmycelia）Myceliacanbedividedintovegatativemyceliumandaerialmycelium（营养菌丝体和气生菌丝体）Basicunit——hypha（pl。hyphae）Thisisatubularcellwhichissurroundedbyarigid,chitin-containingcellwall.Hyphaecontainnuclei,mitochondria,ribosomes,Golgiandmembrane-boundvesicleswithinaplasma-membraneboundcytoplasmmembraneCellwall

mitochondrionVesicalsDictyosomes(分散高尔基体)HyphalstructuresSpecializedmorphologyofvegetativemycelium

营养菌丝体的特化形态Rhizoid假根——Rhizopus

Stolon匍匐菌丝——Mucorales、Rhizopus

Haustorium吸器Adhesivecell附着胞Adhesivebranch附着枝Sclerotium菌核Rhizomorph，funiculus菌索

ringandnet菌环和菌网1)假根(rhizoid)是Rhizopus(根霉属)等低等真菌匍匐菌丝与固体基质接触处分化出来的根状结构，具有固着和吸取养料等功能(2)匍匐菌丝(stolon)又称匍匐枝。毛霉目(Mueorales)真菌在固体基质上常形成与表面平行、具有延伸功能的菌丝，称匍匐菌丝。最典型的可在Rhizopus中见：在固体基质表面的营养菌丝分化为匍匐菌丝，在其上每隔一段距离可长出伸人基质的假根

根霉的形态和构造和伸向空间的孢囊梗，随着匍匐菌丝的延伸，不断形成新的假根和孢囊梗，这类真菌会随基质的存在而向四处快速蔓延，根本就不会形成像在其他真菌中常见的那样有固定大小和形态的菌落。sporangium(3)吸器(haustorium)由几类专性寄生的真菌如锈菌目(Uredinales)、霜霉目(Peronosporales)和白粉菌目(Erysiphales)等的一些种所产生。吸器是一种只在宿主细胞间隙间蔓延的营养菌丝上分化出来的短枝，它可侵入细胞内形成指状、球状或丝状的构造，用以吸取宿主细胞内的养料而不使其致死。(4)附着胞(adhesivecell)许多寄生于植物的真菌在其芽管或老菌丝顶端会发产膨大，分泌粘状物，借以牢固地粘附在宿主的表面，此即附着胞。在其上再形成针状感染菌丝，以侵入宿主的角质表皮而吸取养料。

(5)附着枝(adhesivebranch)若干寄生真菌由菌丝细胞生出1—2个细胞的短枝，将菌丝附着于宿主体上，（6）菌核（sclerotium)是一种形状、大小不一的休眠菌丝组织，在不良外界条件下：可保存数年生命力。菌核形状有大有小，大的如茯苓(大如小孩头)，小的如油菜菌核(形如鼠粪）。菌核的外层色深、坚硬、内层疏松，大多呈白色。（7）菌索（）一般由伞菌等产生，为白色根状菌丝组织，功能为促进菌体蔓延和抵御不良环境。通常可在腐朽的树皮下和地下发现。

(8)菌环(loop)和菌网(net)捕虫菌目(zoopasdes)和一些半知菌的菌丝常会分化成圈环或网状的特化菌丝组织，用以捕捉线虫或其他微小动物，然后进一步从这类环或网上生出菌丝侵入线虫等体内，吸收养料（9）子实体（fruitingbody，sporocarp，fructification）ColonialgrowthHyphaltipgrowthallowsfungitoextendintonewregionsfromapointsourceorinoculum(接种物).Olderpartsofthehyphaeareoftenemptiedofcontentsasthecytoplasmistakenforwardswiththegrowingtip.(老的菌丝通常缺乏内含物，因为细胞质流向生长点)Thiscreatestheradiatingcolonialpatternseenonagarplates,inringworminfectionsofskinandfairyringsingrasslawns.Onlyhyphaltipscontributetoextensiongrowth.Howeverolderhyphaecangrowaeriallyordifferentiatetoproducesporingstructures（只有菌丝顶端对延伸生长起作用，而老菌丝可以进行气生生长或分化出产孢子的结构）MyceliuminagarAgar

SurfacemyceliumKineticsofgrowth

Fungalgrowthinagivenmediumfollowsthegrowthphasesoflag,acceleration,exponential,linear,retardation,stationaryanddecline（延迟期、加速期、指数期、直线期、减速期、稳定期、衰亡期）.Exponentialgrowthoccursonlyforabriefperiodashyphaebranchesinitiated,andthenthenewhyphaextendsatalinearrateintouncolonizedregionsofsubstrate.Lifecycles

Allfungiarecharacterizedbyhavingaperiodofvegetativegrowthwheretheirbiomassincreases.Thelengthoftimeandtheamountofbiomassneededbeforesporulationcanoccurvaries.Almostallfungireproducebytheproductionofspores,butafewhavelostallsporingstructuresandarereferredtoasmyceliasterilia(不育菌丝体).Differenttypesofsporeareproducedindifferentpartsofthelifecycle.ReproductioninfungiAllfungiundergoaperiodofvegetativegrowthwheretheirmyceliumexploitsasubstrate.Thisstageisfollowedbyasexualandsexualreproduction..

Therearetwoconflictingrequirementsfungihavefortheirspores.Sporesmustallowfungitospread,buttheymustalsoallowthemtosurviveadversecondi­tions.Theserequirementsaremetbydifferenttypesofspores.Small,lightsporesarecarriedfurthestfromparentmyceliuminairandthesearethedispersalspores（释放型孢子）.Theyareusuallytheproductsofasexualsporulation,thesporangiosporesandtheconidiospores,andsospreadgeneticallyidenticalindividualsaswidelyaspossible.Geneticdiversityismaintainedbysexualreproduction,andthesporeproductsareoftenlargerestingspores（休眠孢子）thatwithstandadverseconditionsbutremainclosetotheirsiteofformation.Sporesthereforevarygreatlyissize,shapeandornamentation,andthisvariationreflectsspecializationofpurpose.Fungalspores：sporesallowfungitospread,tomaintaingeneticdiversityandtosurviveadverseconditionsReproductioninfungi

sporedischarge

：Sporesthathaveadispersalfunctioncanbereleasedfromtheirparentmyceliumbyactiveorpassivemechanisms.Asmanysporesarewinddispersed,theyareproducedindryfriablemasseswhicharepassivelydischargedbywind.Othersporesarepassivelydischargedbywaterdropletssplashingsporesawayfromparentmycelium.Sporesmaybedischargedfromparentmyceliumbypassiveoractivemeans.Passivemechanismsincludeusingwindandwaterasdispersants;activemechanismsuseexplosiveprinciples.Fungalsporedischarge

Sporesintheatmosphere（air-bornefungalspores）canbecarriedgreatdistances。Theirpresenceintheaircanhaveimpactonhumanhealthastheycancauseallergicrhinitus（hayfever）andasthma。Manyplantdiseasesthatcausegreateconomiclossesareairborne。canaffecthuman,animalandplanthealth.Theycancauseallergiesandspreadplantdisease.AirsporaFungireproducebytheformationofsexualorasexualspores

AsexualreproductionfissionArthrosporeBuddingblastosporeOtherasexualsporeZoosporeChlamydosporeSporangiosporeconidiospora

Sexualreproduction

OosporeZygosporeAscosporeBasidiospore节孢子(arthrospore)某些真菌生长到一定阶段，菌丝中间形成许多隔膜，接着从隔膜处断裂成许多竹节似的无性孢子，称为节孢子，也称为粉孢子。最典型的例于是白地霉(Geotrichumcandidum).arthrosporeBlastospore(芽孢子)

这和酵母菌的出芽一样，它是由母细胞生芽而形成的。当芽长到正常大小时，脱离母细胞，或仍连在母细胞上。如玉蜀黍黑粉菌(Ustilagomaydis)能产生芽孢子。某些毛霉或根霉在液体培养基中形成的被称为酵母型细胞，也属芽孢子。

又称厚壁孢子或厚膜孢子。某些真菌生长到—定阶段，在菌丝的顶端或中间有部分细胞的细胞质密集在一起，变圆，然后在其四周生出厚壁，或原细胞壁加厚，形成圆形、纺锤形的无性休眠体，来抵抗外界不良的环境条件。例如总状毛霉(Mucorracemosus)往往在菌丝中间形成许多厚垣孢子schlamydospore（厚垣孢子）

无性繁殖产生的孢子在孢子囊(Sporange)内,孢子囊一般生在气生菌丝的顶端或生在孢囊梗(sporangiophore)的顶端。在形成孢子囊前，首先有多核的原生质密集于此处，使其膨大，并在下方生出横隔，形成圆形的囊状物，然后其中原生质体割裂成许多小块，每—块发育成为—个孢子囊孢子。因而每一·个孢子囊所含有的孢子的数—般都相当多。就孢子囊孢子而言,—般有二类,一种具有—根或2~3根鞭毛，能够游动，所以称游动孢子(zoospore)。例如腐霉(即thium)。另一种无鞭毛，不能游动，又称静止担于。sporangiospore

(孢子囊孢子)游动孢子

conidium

(分生孢子)

分生孢子的形成方法其形成方式有两种，一种是在分生孢子梗的顶端突出，发育成第一个孢子。梗再伸长形成第二个孢子，如此重复形成一串孢子。这样形成的分生孢子，顶端的最老。曲霉属和青霉届的分生孢子形成，即属于此类型。

另一种是在第—个分生孢子形成时，柄的长度已达到最高，由第一个分生孢子顶端生长出第二个分生孢子，如此重复形成一串孢子。这样形成的分生孢子，下部的最老。如枝孢霉属(Cladosporium)的分生孢子形成即属于此类型。Plastickitchencuttingboardsurface-rodbacteriainasmoothmatrix;filamentousbacteria(丝状菌)-smoothovalcells;fungalhyphae(真菌菌丝)withtexturedspores(结构孢子)(x2,270)conidiumZoospore（游动孢子）Asexualspore，usually

producedbyfungilivinginwater.Motilezoosporesinmotilesporangiadifferentiatedfromswelledhyphaltipshaveasingleposteriorflagellum。Thestructureoftheflagellumis9+2，somehastwoflagella.

霉菌的有性繁殖是经过不同性别的细胞结合(质配和核配)后，产生一定形态的孢子来实现的，这种孢子称为有性孢子。繁殖过程可分为三个阶段：第—个阶段为质配；第二个阶段为核配，产生二倍体的核；第三个阶段是减数分裂，恢复核的单倍体状态。大多数真菌菌体是单倍体的。有性孢子通常有下列几种：Sexualreproduction

菌丝分为雄器(antheridium)和藏卵器(oogonium)。藏卵器中有一个或数个卵球(oosphere)。当雄器和藏卵器相配时，雄器中细胞质与细胞核，通过受精管而进入藏卵器，与卵球结合形成卵孢子。图所示是德巴利腐霉的卵孢子的形成。oospore

(卵孢子)

（b）同宗结合（a）异宗结合根霉的接合孢子Zygospore（接合孢子）ascospore（子囊孢子）形成子囊孢子是子囊菌的主要特征。子囊中孢子数目通常为1~8个，或为2n。典型的子囊中有8个孢子。大多数霉菌的子囊是包裹在子囊果（ascocarp）中。子囊果有三种类型子囊壳perithecium子囊盘apothecium闭囊壳cleistotheciumSexualreproductioninthisgroupoccursaftersomaticfusionofdifferentmating-typemycelia.Atransientdiploidphaseisrapidlyfollowedbytheformationofascosporeswithinsac-shapedascidifferentiatedfrommodifiedhyphaltips.Intheinitialstagesofascaldevelopmenthookedhyphaltipsform,calledcroziers（产囊丝钩）orshepherds‘crooks（牧羊杖）

becauseoftheirshape.Theyhavedistinctiveseptaeattheirbasewhichinsurethattwodifferentmating-typenucleiaremain­tainedintheterminalcell.Formationoftheseptaeiscoordinatedwithnucleardivision.Inyeastsalltheseeventsoccurwithinonecell,afterfusionoftwomating-typecells,thewholecellbeingconvertedintoanascus.TheformationofascosporesSexualreproductionintheascomycetes

InmorecomplexAscomycetesmanyasciformtogether,creatingafertiletissuecalledahymenium（叫子实层的能育组织）.Insomegroupsthehymeniumcanbesupportedorevenenclosedbylargeamountsofvegetativemycelium.Thewholestructureiscalledafruitbodyorsporocarp（子囊果）andisusedasamajortaxonomicfeature.Theycanbecomelargeenoughtobeseenwiththenakedeye.Flask-shapedsexualreproductivebodiesarecalledperithecia,cup-shapedbodiesarecalledapotheciaandclosedbodiesarecalledcleistothecia.Thesestructureshaveevolvedtoprotecttheasciinsporedispersal，butthehymeniumitselfisunafectedbythepresenceofwater。TheformationofsporocarpanditsformsCup-shapedapotheciumFlask-shapedperitheciumClosedcleistotheciumAsciAsciAscuscontainingascosporesBasidiomycetefungirarelyreproduceasexually.Sexualreproductionisbytheformationofbasidiosporesonthegillsorporesoflargefruitgroupoffungiarecharacterizedbythemostcomplexandlargestructuresfoundinthefungi.Theyarealsodistinctiveinthattheyveryrarelyproduceasexualspores.Muchofthelifecycleisspentasvegetativemycelium,exploitingcomplexsubstrates.Apreliminaryrequisitefortheonsetofsexualreproductionistheacquisitionoftwomatingtypesofnucleibythefusionofcompatiblehyphae.Singlerepresentativesofthetwomating-typenucleiareheldwithineveryhyphalcompartmentforextendedperiodsoftime.Thisistermedadikaryoticstate（双核期）,anditsmaintenancerequireselaborateseptumformationduringgrowthandnucleardivision.Basidiospore

Onsetofsexual-sporeformationistriggeredbyenvironmentalconditionsandbeginswiththeformationofafruitbodyprimordium（子实体原基）.Dikaryoticmycelium（双核菌丝体）expandsanddifferentiatestoformthelargefruitbodieswerecognizeasmushroomsandtoadstools（毒蕈）.Diploidformationandmeiosisoccurwithinamodifiedhyphaltipcalledabasidium。Basidiumformation核融合Nuclearfusion减数分裂meiosis担孢子梗sterigmataBasidiospores担孢子Basidium（担子）BasidiumandbasidiosporeformationFoursporesarebuddedfromthebasidium.Basidiaformtogethertocreateahymeniumwhichishighlysensitivetothepresenceoffreewater.Thehym-eniumisdistributedoversterile,dikaryoticsupportingtissueswhichprotectitfromrain.Thehymeniumcanbeexposedongillsorporesbeneaththefruitbody,seeninthetoadstoolsandbracketfungi,orenclosedwithinchambersasinthepuffballsandtrufflesFormationofbasidiosporepuffball（马勃）Bracket（檐状伞）

Toadstool（毒蘑菇）Hymenenium（子实层）Structureofsexualsporocarpsinthebasidiomycetesbasidiospore（担孢子）担孢子是担子菌特有的特征。它是一种外生孢子，经过两性细胞核配合后产生。因为它生在担子上，所以称为担孢子。典型的担子菌的担子上有四个担孢子。各种担孢子的形状及表面特征Foodrelatedmolds1.Aspergillus

曲霉属2.penicillium（青霉属）3.Rhizopus

（根霉属）4.sporotrichum(侧孢霉属)5.Thamnidium(枝霉属)6.Alternaria（交链孢属）7.Botrytis（葡萄孢霉）（木霉属）（红曲属）（赤霉属）

11.Cordyceps（虫草属）（地霉属）（长蠕孢霉）foodrelatedMouldsAspergillus曲霉属分生孢子初生小梗孢子穗小梗次生小梗顶囊足细胞ConidiaprimarysterigmaconidialheadsterigmesecondarysterigmaVesiclefootcellMorphologyofConidialheadisthebasisforspeciesidentification孢子穗的形态是菌种鉴定的依据AspergillusRelationshipwithfood——beneficialFermentationindustrysoysauce酿酱vinegar制醋曲

fermentedbeancurd腐乳alcoholbeverage酿酒Foodprocessingorganicacid有机酸enzyme酶制剂

淀粉酶蛋白酶果胶酶等Relationshipwithfood——harmfulUsuallydistributedonthesurfaceoffollowingfoodstuff：Cakes、fruits、vegetables、meat、grainandotherorganicobjects。Causingfollowingconsequences：Gomouldy；becomemildewedProduceorsecretecarcinogenicsubstance（blastomogen）致癌物质eg。aflatoxin（黄曲霉毒素）Foodrelatedmolds——penicillium（青霉属）

十分接近于曲霉，在自然界分布很广，长生长在腐烂的柑橘皮上，呈青绿色，不少种类引起食品变质，但也用来生产青霉素和有机酸等。青霉菌菌丝与曲霉相似，但无足细胞，孢子穗结构也不同。其分生孢子梗顶端不膨大，而是经过多次分枝产生几轮对称或不对称的小梗，然后在小梗的顶端产生成串的分生孢子。青霉菌的孢子穗形状似扫帚状。分生孢子球形、椭圆形或短柱形，一般呈蓝绿色。

Plastickitchencuttingboardsurface-rodbacteriainasmoothmatrix;filamentousbacteria(丝状菌)-smoothovalcells;fungalhyphae(真菌菌丝)withtexturedspores(结构孢子)(x2,270)根霉在自然界分布广泛，经常出现在淀粉质食品上，引起粮食、食品腐烂、腐败。I工业上常利用根霉生产糖化酶，甜酒曲中主要菌种也是根霉。此外，根霉也可以用来生产有机酸等其它物质。Foodrelatedmolds——Rhizopus（根霉属）Rhizoid假根Stolen匍匐丝

sporangeUauallyblacksporangiophore

菌丝分隔·分生孢子梗分枝，顶端产生分生孢子。分生孢子单细胞，梨形。菌落呈奶油色泽，时间长后，为干燥粉末状。已经报告该菌能在O~C以下生长，常在冷藏肉中形成白色斑点。

foodrelatedmolds—sporotrichum

(侧孢霉属)S．Carnis肉色侧孢霉Conidium分生孢子Conidiophore分生孢子梗Causethedeteriorationofvegetablesandfruitconidiumconidiophore形状大小不定，数个连接成链，暗褐色，有纵横隔膜，呈壁砖状。大多数不分支，较短，单生或成簇，暗褐色。Foodrelatedmolds——Alternaria（交链孢属）septatemyceliumFoodrelatedmolds——Botrytis（葡萄孢霉）conidiophoreconidium分生孢子梗顶端形成树枝状分支，分支顶端细胞常常膨大，在短的小梗上着生分生孢子，如一串葡萄。卵圆形，无色或暗褐色。常产生外形不规则的黑色菌核（sclerotium）。分布在许多植物和植物食品上，形成一层“灰色霉”，引起水果、蔬菜的腐败。Foodrelatedmolds——Trichoderma（木霉属）Sphericalorelliptical（oval），smmothorrough，yellow-greenconidiaColorlesshypha，withseptaandbranches，producechlamydosporesBottle-likesterigme瓶状小梗Sporeheadgathered（conglutenated）bymucus（slime）Foodrelatedmolds——Trichoderma（木霉属）Colonygrowsrapidly，likecottonfibre（棉絮状），whiteatfirst，laterbecomegreen。Spore-producingareatakeson（has）concentriccirclesSonespecieshascellulolyticactivity，thereforecanbeusedtoproducecellulasetomanufacturesugarswithcellularwaste（下脚），starchprocessingandfoodprocessing

Moldygrain，fruitandvegetablesMildewandrotofcellularmaterial。Foodrelatedmolds——Monascus（红曲属）CansecreteredpigmentThesourceofnaturalredpigmentinthefoodprocessing，forinstanceredrice（ang-kak）usedintheprocessingofredfermentedbeancurd，bevarageandmeatispreparedfromMonascus。Typeculturethatcommonlyused：M.purpureus（紫红曲）Foodrelatedmolds——Monascus（红曲属）Colonyfeatures：membranouscolonycoversthewholemaltextractplate，myceliumiswhiteatfirst，laterbecomesred，red-purple，thewater-solublepigmentsaresecretedintothemedium。conidiumFoodrelatedmolds——Monascus（红曲属）1~3initiatecleistothecium4~5prematurecleistothecium

6maturecleistothecium

cleistotheciumof

紫红曲的闭囊壳Foodrelatedmolds——Gibberella（赤霉属）reproduction

scarcelyproduceSexualgeneratin（gamobium，sexualprogeny），sexualsporeisascosporeinspherical，smoothandblueperithecium（子囊壳）。

AsexualreproductionproducetwotypesofconidiumSmalltype：singlecellular，spherical，ellipticaltolongcolumn，colorlessorothercolorsLargetype：multicellularwithsepta，Sickle-likeorlongcolumn，ColorlessorothercolorsFoodrelatedmolds——Gibberella（赤霉属）Gibberellinorabbeymycin（赤霉素）MetabolicproductofGibberella，isakindofhormonewiththefollowingfunction：1.Stimulateplantgrowth2.Breakthedormancyofseedandtuber3.IncreasetheyieldofvegetablesespeciallyleafyvegetablesFoodrelatedmolds——Cordyceps（虫草属）Formation：Theinsectbodyparasitizedbythefungiwasfullofmycelium（sclerotium菌核）andmummified，stem-headlikeorrodlikestroma（pluralstromata子座）growsoutfromitsfrontend。Inchworm尺蠖

Stroma（grass）usuallysingle，scarcely2or3，4~11cminlength。peritheciumAscus（asci）ascosporeCordycepssinesis冬虫夏草Foodrelatedmolds——geotrichum（地霉属）Reproductionbyfission，septatehypha，hyphamaybreakintoarthrospore，withoutblastospore。

Alwaysexistedinsauerkraut（kimchi，pickles泡菜），fecund，organicfertilizer，rottenfruitandvegetablesandotherplantresidues。ArthrosporegerminationHyphabreaksintofragment----arthrosporeG.Candidum(白地霉)Foodrelatedmolds——helminthosporium（长蠕孢霉）conidiophoreconidium

Colorlessorgrayseptatemycelium，septateconidiophore，conidiumisblack-gray，usuallyhas4~6cells，manyfungiofthegeneraarebothparasiteandsaprobe（saprophyticbacterium，saprogen，saprotroph，腐生菌）Foodrelatedmolds——geotrichum（地霉属）Somespecieshashighnutritionalvalue,hasthefollowingusages:1.Edibleorasforagesupplement2.Nucleicacidextraction3.FatsynthesisEukaryote——yeastDefinition：yeastisagroupofunicelledeukaryoticmicroorganismsreproducedbybudding.

Generallyitreferstoallsingle-celledeukaryotesthatcanfermentcarbohydrates.Eukaryote——yeast

It‘sakindofmicrobesutilizedearlybyhumanbeing.

Mainlyexistsintheacidicenvironmentwithhighsugarcontentsuchasonthefruits，vegetables，flowerhoneyandconfect，orintheorchardsoil.Mostyeastsaresaprophyteandbeneficialtohumanbeing，onlyafewareparasitismandcancausethehumanbeing，plantandanimaldiseases.

Someyeastscanleadtothedeteriorationoffruitjuice，jam，honey，alcoholbeverage，andmeat.YeastcellmorphologyandstructureMostyeastareunicellusuallyarespherical，ovalorcolumnshape，somespeciesmayformlotusrootshapedpseudomycelium.

DiagramofyeastcellstructureSaccharomycescerevisiaeis

the

mosttypicalandthemostimportantyeast.Thefigurerightshowsitscellstructure.membranevacuoleCellwallmitochondrionNucleusEndoplasmicreticulumThemajorcomponentsofyeastcellwallareglucan（葡聚糖）and

mannan（甘露聚糖），anddifferentamountofproteins，lipidsandchitin（几丁质）.Infantcellshashomologouscytoplasm，latervacuoleemerged.Yeaststructures

Colonialmorphology

Likebacterialcolonies，yeastcolonyhasfollowingfeatures：wettish（humid）、alittletransparent，withlubricous（光滑的slippery）surfaceandeventextureandcanbeeasilypickedup，theobversesideandthereversoside，theedgeandthecenterhasthesamecolor.Otherhand，itisbigger，thicker，denser，andalittleopaquethanthatofbacterium.Comparedwithbacteria，itscolonyonlyhasseveralcolors，normallyismilkwhiteorcandlewhite（矿烛色），fewarered，oneortwoisblack.Thosewithoutpseudomyceliumhasbulgedcolonywithroundedge，whileCandidahastheflatcolonywithcoarsebrinkandsurface.Reproductionofyeast

Budding:byallyeastsAsexualfission:byschizosaccharomycetesarthrosporeAsexualsporulationballistosporechlamydosporeSexual:byformationofascusandascosporeBuddingWhenyeastgrowsonaplateofrichnutritionandunderoptimalculturecondition，itmultiplyrapidly，nearlyallcellsarebudding，therefore，conglomeratedintocellclusters（balls）.Afteraseriesofbudding，ifdaughteryeastsdon‘tdepartfromparentcells，andonlylinkedbynarrowandsmallarea，thusformedlotusrootshapedcellstringscalledpseudohyphae.PseudohyphaeandeuhyphaeOtherwise，cellslinkedandtheseptaareaisthesameascelldiameterformedlaemodipodiform（竹节形）cellstrings，thatiscalledeuhyphae

euhyphae

。Whendaughteryeastdepartfromtheparentcell，Scarwasleavedonbothofthem，calledbudscar（onparentcell）andbirthscar（ondaughtercell）respectively.Budscarandbirthscar光学显微镜下看到的酵母细胞这里显示的菌种是用来发面团以及将葡萄汁转变成酒的那些细胞。他们繁殖时先出芽，进而不对称分裂为一大一小两个子细胞酿酒酵母（saccharomycescerevisiae）Foodrelatedyeasts(1)——saccharomyces（酵母属）

Saccharomyceswidelycolonizedonfruitsandvegetables，orchardandseedyeast（酒曲）.Spherical，elliptical，sausage-shapedreproducedbymulti-endsbuddingorsexuallyproducing1~4ascospores.

Strongfermentativeability，majorproductsareethonalandco2.Can‘tuselactoseandhigh-levelhydrocarbon（烃类).features

Manyspeciesarewidelyusedinindustry，forinstanceS.cerevisiae（酿酒酵母）

canbeusedinbrewingofbeer，alcoholandotherbeverages，aswellasbreadmaking.

Beneficial

Somecausethefruitandvegetablefermentation，thereforecausefooddecay.Forexample

（鲁氏毛霉）andS.Melliscan（蜂蜜酵母）aretoleranttosugarsolutionofhighconcentrationcausethespoilageordeteriorationofjamandotherfoods.Theycanalsosurviveinhighconcentrativesaltsolution，liveinsoysauceandformalayerofgray-white，powder-likepellicle，thusaffectthequalityofsoysauce.Detrimental酿酒酵母的光镜照片Saccharomycescerevisiae

酿酒酵母SEM10μmFoodrelatedyeasts（2）Brettanomyces（酒香酵母属）Somespeciesinvolvedinthepost-fermentativeperiodinthebrewingofsomeEuropebeers.SomeotherspeciescanbeisolatedfromdeterioratedKraut，fruitsandvegetables.（3）Candida（假丝酵母属）Normallyexistsonthesurfaceoffreshandsaltedmeatandothermanyfoods.Foodrelatedyeasts(4)Debaromyces（德巴利酵母属）Usuallycanbeisolatedfromtheflowingdeterioratedfood：meat，sausageandalcoholbeverages.(5)Endomycopsis（拟内酵母属）

Formeuhyphaeandusuallyformathinlayerofpellicle,canbedetectedfromflowingfoods：grains，fermentedsauerkrautorcucumberandSomespeciescanbeusedtoproduceαandβamylase.(6)Hansenula（汉逊酵母属）

Usuallyformedpseudohyphae，growsonoranges，grapeandthetheirproductorcondensedjuice.Foodrelatedyeasts(7)Kloeckera（克勒克酵母属）

Thisgroupcanbothinvolveinthefermentationandoxidation，usuallygrowsonfruitthecontaminatedbythefruitflies.Somespeciescanleadstotheabnormalsmellorturbidityofalcoholicbeverages.(8)Mycoderma（醭酵母属）Formathicklayerofmycoderm（pellicle）floatedabovethebeer，vinegar，sauerkraut,fruitjuiceandtheirproduct.Foodrelatedyeasts(10)Rhodotorula（红酵母属）

Widelyexistedintheenvironment，manycanproduceredpigmentonfoodormedium，Somespeciescancausehumanandanimaldiseases.(9)Pichia（毕赤氏酵母属）Contaminativefungiofalcoholindustry，alwaysforma