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单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,单击此处编辑母版标题样式,*,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,Chapter 2,Morphology,，,structure and physiological function of eukaryotes,Definition,：,eukaryotic cells are compartmentalized by membran-es .The cell contains several different types of membrane bou- nd organelle in which different biochemical and physiological processes can occur in a regulated way.,Membranes also transport information,，,metabolic intermediats and end-products from the site of biosynthesis to the site of use.,Eukaryotes is a big group of living organisms made up of eukaryotic membrane bound nucleus and several organelles such as mitochondrion divided by mitosis,.,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,.,eukaryotic micro-organisms is a group of Microorganisms that made up of eukaryotic cells include Fungi、microalgae、and protozoa,真核细胞,真核生物,真核微生物,peroxisomes,mitochondrion,cytosol,chloroplast,Smooth endoplasmic reticulum,Structure of a typical plant cell,Cytosol,细胞液,Plasma membrane,Secretory vesicles,Structure of a typical animal cell,membrane,Cell wall,mitochondrion,Vesicals,(,泡囊,),Dictyosomes (,分散高尔基体,),Hyphal structures,Endoplasmic reticlum,ribosomes,membrane,vacuole,Cell wall,mitochondrion,Nucleus,Endoplasmic reticulum,Yeast structures,Yeast structures,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True Fungi)、,粘菌(Myxomycota或Fungilike Protozoa)、,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),Major groups of eukaryotic microorganisms,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unicellular fungi,真菌 eumycota 丝状真菌filamentous,大型子实体 蕈菌 mushroom,Major groups of eukaryotic microorganisms,Eukaryotic microorganisms,“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、依靠细胞外表吸收有机养料、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：,无叶绿素，不能进行光合作用；,一般具有兴旺的菌丝体；,细胞壁多数含几丁质；,营养方式为异养吸收型；,以产生大量无性和(或)有性孢子的方式进行繁殖；,陆生性较强,Fungi are filamentous, non-photosynthetic, eukaryotic microorganisms that have a heterotrophic nutrition . Their basic cellular unit is described as a hypha,.,This is a tubular cell which is surrounded by a rigid, chitin-containing cell wall. The hypha extends by tip growth, and multiplies by branching, creating a fine network called a mycelium. Hyphae contain nuclei, mitochondria, ribosomes, Golgi and membrane-bound vesicles within a plasma-membrane bound cytoplasm .,The subcellular structures are supported and organized by microtubules and endoplasmic reticulum. The cytoplasmic contents of the hypha tend to be concentrated towards the growing tip. Older parts of the hypha are heavily vacuolated and may be separated from the younger areas by cross walls called septae. Not all fungi are multicellular, some are unicellular and are termed yeasts. These grow by binary fission or budding, creating new individuals from the parent cell.,Mould Mold,Definition,Mold are filamentous, nonphotosynthetic, eukaryotic microorganisms that have a heterotrophic nutritionfilamentous fungi。,Morphology and structure,Hypha and mycelium,菌丝与菌丝体,lower funginon-septate mycelium,s higher fungiseptate mycelium with elaborate,、,perforate septa,The hypha extends by tip growth, and multiplies by branching, creating a fine network called a mycelium. plural mycelia,Mycelia can be divided into vegatative mycelium and aerial mycelium营养菌丝体和气生菌丝体,Basic unithyphapl。 hyphae This is a tubular cell which is surrounded by a rigid, chitin-containing cell wall. Hyphae contain nuclei, mitochondria, ribosomes, Golgi and membrane-bound vesicles within a plasma-membrane bound cytoplasm,membrane,Cell wall,mitochondrion,Vesicals,Dictyosomes (,分散高尔基体,),Hyphal structures,Specialized morphology of vegetative mycelium,营养菌丝体的特化形态,Rhizoid,假根,Rhizopus,Stolon,匍匐菌丝,Mucorales,、,Rhizopus,Haustorium,吸器,Adhesive cell,附着胞,Adhesive branch,附着枝,Sclerotium,菌核,Rhizomorph,，,funiculus,菌索,ring and net,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外表平行、具有延伸功能的菌丝，称匍匐菌丝。最典型的可在Rhizopus中见：在固体基质外表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(adhesive cell) 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外表，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(adhesive branch) 假设干寄生真菌由菌丝细胞生出12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fruiting body，sporocarp， fructification,Colonial growth,Hyphal tip growth allows fungi to extend into new regions from a point source or inoculum(接种物). Older parts of the hyphae are often emptied of contents as the cytoplasm is taken forwards with the growing tip. (老的菌丝通常缺乏内含物，因为细胞质流向生长点)This creates the radiating colonial pattern seen on agar plates , in ringworm infections of skin and fairy rings in grass lawns. Only hyphal tips contribute to extension growth. However older hyphae can grow aerially or differentiate to produce sporing structures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,Mycelium in agar,Agar,Surface mycelium,Kinetics of growth,Fungal growth in a given medium follows the growth phases of lag, acceleration, exponential, linear, retardation, stationary and decline延迟期、加速期、指数期、直线期、减速期、稳定期、衰亡期 .Exponential growth occurs only for a brief period as hyphae branches initiated, and then the new hypha extends at a linear rate into uncolonized regions of substrate.,Life cycles,All fungi are characterized by having a period of vegetative growth where their biomass increases. The length of time and the amount of biomass needed before sporulation can occur varies. Almost all fungi reproduce by the production of spores, but a few have lost all sporing structures and are referred to as,mycelia sterilia(,不育菌丝体,).,Different types of spore are produced in different parts of the life cycle.,Reproduction in fungi,All fungi undergo a period of vegetative growth where their mycelium exploits a substrate. This stage is followed by asexual and sexual reproduction.,.,There are two conflicting requirements fungi have for their spores. Spores must allow fungi to spread, but they must also allow them to survive adverse conditions. These requirements are met by different types of spores. Small, light spores are carried furthest from parent mycelium in air and these are the dispersal spores释放型孢子. They are usually the products of asexual sporulation, the sporangiospores and the conidiospores, and so spread genetically identical individuals as widely as possible. Genetic diversity is maintained by sexual reproduction, and the spore products are often large resting spores休眠孢子 that withstand adverse conditions but remain close to their site of formation. Spores therefore vary greatly is size, shape and ornamentation, and this variation reflects specialization of purpose.,Fungal spores,：,spores allow fungi to spread, to maintain genetic diversity and to survive adverse conditions,Reproduction in fungi,spore discharge,：,Spores that have a dispersal function can be released from their parent mycelium by active or passive mechanisms,.,As many spores are wind dispersed, they are produced in dry friable masses which are passively discharged by wind. Other spores are passively discharged by water droplets splashing spores away from parent mycelium,.,Spores may be discharged from parent mycelium by passive or active means. Passive mechanisms include using wind and water as dispersants;,active mechanisms use explosive principles.,Fungal spore discharge,Spores in the atmosphereair-borne fungal spores can be carried great distances。Their presence in the air can have impact on human health as they can cause allergic rhinitus hay feverand asthma。 Many plant diseases that cause great economic losses are air borne。can affect human, animal and plant health. They can cause allergies and spread plant disease.,Air spora,Fungi reproduce by the formation of sexual or asexual spores,Asexual reproduction,fission,Arthrospore,Budding,blastospore,Other asexual spore,Zoospore,Chlamydospore,Sporangiospore,conidiospora,Sexual reproduction,Oospore,Zygospore,Ascospore,Basidiospore,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).,arthrospore,Blastospore (,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,(Ustilago maydis),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局部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(Mucor racemosus)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,23,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，柄的长度已到达最高，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。,Plastic kitchen cutting board surface - rod bacteria in a smooth matrix; filamentous bacteria (,丝状菌,) -smooth oval cells; fungal hyphae (,真菌菌丝,) with textured spores (,结构孢子,) (x 2,270),conidium,Zoospore游动孢子,Asexual spore,，,usually,produced by fungi living in water .Motile zoospores in motile sporangia differentiated from swelled hyphal tips have a single posterior flagellum,。,The structure of the flagellum is 9+2,，,some has two flagella.,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。有性孢子通常有以下几种：,Sexual reproduction,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18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,cleistothecium,Sexual reproduction in this group occurs after somatic fusion of different mating-type mycelia. A transient diploid phase is rapidly followed by the formation of ascospores within sac-shaped asci differentiated from modified hyphal tips. In the initial stages of ascal development hooked hyphal tips form, called croziers 产囊丝钩or shepherds crooks牧羊杖 because of their shape. They have distinctive septae at their base which insure that two different mating-type nuclei are maintained in the terminal cell. Formation of the septae is coordinated with nuclear division . In yeasts all these events occur within one cell, after fusion of two mating-type cells, the whole cell being converted into an ascus.,The formation of ascospores,Sexual reproduction in the ascomycetes,In more complex Ascomycetes many asci form together, creating a fertile tissue called a hymenium叫子实层的能育组织. In some groups the hymeniumcan be supported or even enclosed by large amounts of vegetative mycelium. The whole structure is called a fruit body or sporocarp子囊果 and is used as a major taxonomic feature . They can become large enough to be seen with the naked eye. Flask-shaped sexual reproductive bodies are called perithecia, cup-shaped bodies are called apothecia and closed bodies are called cleistothecia. These structures have evolved to protect the asci in spore dispersal， but the hymenium itself is unafected by the presence of water。,The formation of sporocarp and its forms,Cup-shaped apothecium,Flask-shaped perithecium,Closed cleistothecium,Asci,Asci,Ascus containing ascospores,Basidiomycete fungi rarely reproduce asexually. Sexual reproduction is by the formation of basidiospores on the gills or pores of large fruit group of fungi are characterized by the most complex and large structures found in the fungi. They are also distinctive in that they very rarely produce asexual spores. Much of the life cycle is spent as vegetative mycelium, exploiting complex substrates. A preliminary requisite for the onset of sexual reproduction is the acquisition of two mating types of nuclei by the fusion of compatible hyphae. Single representatives of the two mating-type nuclei are held within every hyphal compartment for extended periods of time. This is termed a dikaryotic state双核期, and its maintenance requires elaborate septum formation during growth and nuclear division .,Basidiospore,Onset of sexual-spore formation is triggered by environmental conditions and begins with the formation of a fruit body primordium子实体原基. Dikaryotic mycelium双核菌丝体 expands and differentiates to form the large fruit bodies we recognize as mushrooms and toadstools毒蕈. Diploid formation and meiosis occur within a modified hyphal tip called a basidium 。,Basidium formation,核融合,Nuclear fusion,减数分裂,meiosis,担孢子梗,sterigmata,Basidiospores,担孢子,Basidium,担子,Basidium and basidiospore formation,Four spores are budded from the basidium. Basidia form together to create a hymenium which is highly sensitive to the presence of free water. The hym-enium is distributed over sterile, dikaryotic supporting tissues which protect it from rain. The hymenium can be exposed on gills or pores beneath the fruit body, seen in the toadstools and bracket fungi, or enclosed within chambers as in the puffballs and truffles,Formation of basidiospore,puffball 马勃,Bracket,檐状伞,Toadstool毒蘑菇,Hymenenium,子实层,Structure of sexual sporocarps in the basidiomycetes,basidiospore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外表特征,Food related molds,1. 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,food related Moulds,Aspergillus,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,Conidia,primary sterigma,conidial head sterigme,secondary sterigma,Vesicle,foot cell,Morphology of Conidial head is the basis for species identification,孢子穗的形态是菌种鉴定的依据,Aspergillus,Relationship with foodbeneficial,Fermentation industry,soy sauce,酿酱,vinegar,制醋曲,fermented bean curd,腐乳,alcohol beverage,酿酒,Food processing,organic acid,有机酸,enzyme,酶制剂,淀粉酶,蛋白酶,果胶酶等,Relationship with foodharmful,Usually distributed on the surface of following foodstuff,：,Cakes,、,fruits,、,vegetables,、,meat,、,grain and other organic objects,。,Causing following consequences：,Go mouldy；become mildewed,Produce or secrete carcinogenic substanceblastomogen致癌物质,eg 。 aflatoxin黄曲霉毒素,Food related moldspenicillium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，而是经过屡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。,Plastic kitchen cutting board surface - rod bacteria in a smooth matrix; filamentous bacteria (,丝状菌,) -smooth oval cells; fungal hyphae (,真菌菌丝,) with textured spores (,结构孢子,) (x 2,270),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。,Food related moldsRhizopus 根霉属,Rhizoid,假根,Stolen,匍匐丝,sporange,Uaually black,sporangiophore,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，为枯燥粉末状。,已经报告该菌能在OC以下生长，常在冷藏肉中形成白色,斑点。,food related moldssporotrichum,(,侧孢霉属,),S,Carnis,肉色侧孢霉,Conidium,分生孢子,Conidiophore,分生孢子梗,Cause the deterioration of vegetables and fruit,conidium,conidiophore,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。,Food related moldsAlternaria交链孢属,septate mycelium,Food related moldsBotrytis 葡萄孢霉,conidiophore,conidium,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。,常产生外形不规那么的黑色菌核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。,Food related moldsTrichoderma木霉属,Spherical or ellipticaloval，smmoth or rough，yellow-green conidia,Colorless hypha,，,with septa and branches,，,produce chlamydospores,Bottle-like sterigme,瓶状小梗,Spore head gatheredconglutenated by mucusslime,Food related moldsTrichoderma木霉属,Colony grows rapidly，like cotton fibre棉絮状，white at first，later become green。Spore-producing area takes onhas concentric circles,Sone species has cellulolytic activity，therefore can be used to produce cellulase to manufacture sugars with cellular waste下脚，starch processing and food processing,Moldy grain,，,fruit and vegetables,Mildew and rot of cellular material,。,Food related moldsMonascus红曲属,Can secrete red pigment,The source of natural red pigment in the food processing，for instance red riceang-kakused in the processing of red fermented bean curd，bevarage and meat is prepared from Monascus。,Type culture that commonly used：M. purpureus紫红曲,Food related moldsMonascus红曲属,Colony features,：,membranous colony covers the whole malt extract plate,，,mycelium is white at first,，,later becomes red,，,red-purple,，,the water-soluble pigments are secreted into the medium,。,conidium,Food related moldsMonascus红曲属,13 initiate,cleistothecium,45 premature cleistothecium,6 mature,cleistothecium,cleistothecium of,紫红曲的闭囊壳,Food related moldsGibberella赤霉属 reproduction,scarcely produce Sexual generatin gamobium ，sexual progeny，sexual spore is ascospore in spherical ，smooth and blue perithecium子囊壳。,Asexual reproduction produce two types of conidium,Small type,：,single cellular,，,spherical,，,elliptical to long column,，,colorless or other colors,Large type,：,multicellular with septa,，,Sickle-like or long column,，,Colorless or other colors,Food related moldsGibberella赤霉属,Gibberellin or abbeymycin 赤霉素,Metabolic product of Gibberella,，,is a kind of hormone with the following function,：,1.Stimulate plant growth,2.Break the dormancy of seed and tuber,3.Increase the yield of vegetables especially leafy vegetables,Food related moldsCordyceps虫草属,Formation： The insect body parasitized by the fungi was full of myceliumsclerotium 菌核and mummified， stem-head like or rod like stroma plural stromata 子座grows out from its front end。,Inchworm,尺蠖,Stroma grassusually single， scarcely 2 or 3，411cm in length。,perithecium,Ascusasci,ascospore,Cordyceps sinesis,冬虫夏草,Food related moldsgeotrichum地霉属,Reproduction by fission,，,septate hypha,，,hypha may break into arthrospore,，,without blastospore,。,Always existed in sauerkrautkimchi，pickles泡菜， fecund，organic fertilizer，rotten fruit and vegetables and other plant residues。,Arthrospore,germination,Hypha breaks into,fragment-arthrospore,G. Candidum (,白地霉,),Food related moldshelminthosporium长蠕孢霉,conidiophore,conidium,Colorless or gray septate mycelium，septate conidiophore，conidium is black-gray，usually has 46 cells， many fungi of the genera are both parasite and saprobe saprophytic bacterium，saprogen，saprotroph，腐生菌,Food related moldsgeotrichum地霉属,Some species has high nutritional value, has the following usages:,1. Edible or as forage supplement,2. Nucleic acid extraction,3. Fat synthesis,Eukaryoteyeast,Definition,：,yeast is a group of unicelled eukaryotic microorganisms reproduced by budding.,Generally it refers to all single-celled eukaryotes that can ferment carbohydrates,.,Eukaryoteyeast,Its a kind of microbes utilized
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