Chapter 4
Eukaryotic Microorganisms
Molds
Mushrooms Fungi
Yeasts
Algae
Protozoa
Eukaryotic Microorganisms
Major differences among fungi,algae and protozoans
Fungi are heterotrophic eukaryotic microorganisms,
They are nonphotosynthetic and typically form
reproductive spores.
Algae are phototrophic eukaryotes that contain
photosynthetic pigments within a structure called the
chloroplast
Protozoa are animallike protists exhibiting
heterotrophic nutrition and they can be defined as
usually motile eukaryotic unicellular microorganisms.
The morphology
Reproduction
Classification
Typical species
Fungi
Fungi
1,Filamentous fungi
2,Unicellular fungi
The morphology of filamentous fungi
The filamentous fungi consists of two pats,the
mycelium and the spores.
The filamentous fungi develop multicellular
branching structures known as hyphae,which are
connected filaments of vegetative cells,Integrated
masses of hyphae are called a mycelium.
Each hypha is about 5-10 um wide.
(1)nonseptate; (2)septate
Reproduction
Asexual spores are formed by the aerial mycelium of
one organism,When these spores germinate,they
become organisms that are genetically identical to the
parent,
Sexual spores result from the fusion of nuclei from
two opposite mating strains of the same species of fungus,
Organisms that grow from sexual spores will have genetic
characteristics of both parental strains,
Asexual spores are produced by an individual
fungus through mitosis and subsequent cell division;
there is no fusion of the nuclei of cells,Several types
of asexual spores are produced by fungi,
Asexual Spores
Asexual spores
Sporangiospores（孢囊孢子）
Conidiospores（分生孢子）
Arthrospores or Oidia（节孢子）
Chlamydospores（厚壁孢子）
Sporangiospore
Sporangiospores are formed
within a sporangium
Rhizopus (class Zygomycetes),These are
common bread molds,which cause much food
spoilage,They have nonseptate,It forms rootlike
hyphae called rhizoid,as well as stolons,
Zygospores are produced when plus and minus
strains are both present.
Sporangiospore
rhizoid
Chlamydospores are thick-walled cells
within the hyphae
Chlamydospores
Arthrospores
Conidiospores
Conidiospores are
arranged in chains at the
end of a conidiophore
Conidiospores
A fungal sexual spore results from sexual reproduction,
consisting of three phases:
1,A haploid nucleus of a donor cell (+) penetrates
the cytoplasm of a recipient cell (Plasmogamy).
2,The (+) and (-) nuclei fuse to form a diploid
zygote nucleus (Karyogamy).
3,By meiosis,the diploid nucleus gives rise to
haploid nuclei (sexual spores),some of which may
be genetic recombinants (Meiosis).
Sexual Spores
The method of a serial dilutions for viable counting
Chlamydospore External Mucor racemosus
arthrospore External Geotrichum candidum
Conidiospore External Aspergillus niger
Penicillium notatum
Sporangiospore Internal Rhizopus oryzae
Asexual spores of filamentous fungi
Name of fungus Location of spores Examples
Several types of sexual spores
Oospores（卵孢子）
Zygospores（接合孢子）
Ascospores（子囊孢子）
Basidiospores（担孢子）
The major classes of fungi
Oomycetes
Zygomycetes
Ascomycetes
Basdiomycetes
Deuteromycetes
Fungi hyphae representives Sexual spore
Zygomycetes Non -septate Mucor; Rhizopus Zygospore
Ascomycetes Septate Neurospora;
Saccharomyces
Ascospore
Basidiomyctes Septate Agaricus;
amanita
Basidiospore
Deuteromycetes Septate Aspergillus;
Penicillium
Not found
Classification and major properties of fungi
Oospores （ 卵 胞子）,these are formed within a
special female structure,the oogonium(藏卵器 ),
Fertilization of eggs,or oospheres (卵 球 ),by
male gametes in an antheridium (雄器 ) give rise
to oospores.
antheridium
oospheres
oospores
oogonium
Oospores
formation
Zygospores are large,
thick-walled spores
formed when the tips of
two sexually compatible
hyphae of certain fungi
fuse together.
Zygospores
Ascospores,these single-celled spores are
produced in a sac called an ascus,There are
usually 8 ascospores in each ascus.
various ascocarps formed by different ascomycete fungi.
plectocarp pyrenocarp discocarp
Ascospores formation,1,yeast 2,Neurospora
Basidiospores,These single-celled
spores are borne on a club-shaped
structure called basidium.
Basidiospores
Mushroom
Fungi usually grow better in an acidic pH (5.0),which is too
acidic for the growth of most common bacteria.
Most molds are aerobic,so they grow on surfaces rather
than throughout a substrate,Yeasts are facultative anaerobes.
3,Most fungi are more resistant to osmotic pressures than
bacteria are; most fungi are therefore able to grow in high sugar or
salt concentrations.
4,Fungi are capable of growing on substances with a very
low moisture content,generally too low to support the growth of
bacteria.
5,Fungi require somewhat less nitrogen for growth than
bacteria.
Fungi are capable of using complex carbohydrates,such as lignin
(wood),that most bacteria cannot metabolize,
1,Fungi usually grow better in an acidic pH (5.0),
which is too acidic for the growth of most common
bacteria,
2,Most molds are aerobic,so they grow on surfaces
rather than throughout a substrate,Yeasts are facultative
anaerobes,
3,Most fungi are more resistant to osmotic pressures
than bacteria are; most fungi are therefore able to grow in
high sugar or salt concentrations.
Fungi differ from bacteria in certain
environmental requirements and in the following
nutritional characteristics:
4,Fungi are capable of growing on substances with a
very low moisture content,generally too low to support
the growth of bacteria.
5,Fungi require somewhat less nitrogen for growth than
bacteria.
6,Fungi are capable of using complex carbohydrates,
such as lignin (wood),that most bacteria cannot
metabolize.
Classification of fungi
The classification of fungi,unlike that of
bacteria,is based primarily on the
characteristics of the sexual spores and
fruiting bodies present during the sexual
stages of their life cycles.
However,the perfect life cycle of many
fungi are yet unknown,They are placed in a
special class of Deuteromycetes.
Typical species of filamentous fungi
Mucor (class Zygomycetes),occur
abundantly in soil and on fruits,
vegetables and starchy foods,Some are
used in the manufacture of cheeses,Their
mycelium are nonseptate and are white or
gray,Zygospores are produced when plus
and minus strains are both present,No
stolons or rhizoids.
Rhizopus (class Zygomycetes),These are
common bread molds,which cause much
food spoilage,They have nonseptate,It
forms rootlike hyphae called rhizoid,as
well as stolons,Zygospores are produced
when plus and minus strains are both
present.
Neurospora (Class Ascomycetes),This
genus is widely used in the study of
genetics and metabolic pathways,Two
well-known species are N,Crassa and N,
Sitophila,Some species are responsible
for food spoilage,and some species are
used in industrial fermentations,Certain
species produce ascospores,conidia is
usually oval,Because of the characteristic
pink or red color of the conidia,they are
often called pink bread molds.
Agaricus (Class Basidiomycetes),The
best known species is A,campestris,the
field mushroom and A,bisporus,the
cultivated mushroom,Most of the larger
species of Agaricus are edible.
Aspergillus (Class Deuteromycetes),The
aspergilli are widespread in nature,Some
species are involved in spoilage,They are
important economically because they are
used in a number of industrial fermentations,
including the production of the citric acid and
gluconic acid,A.niger,The aspergilli
produce septate,branching mycelium,
Conidia,the colors are black,brown,and
green.
Penicillium (Class Deuteromycetes ),
Members of them occur widely in nature
Some species cause rot or other spoilage,
Some are used in industrial fermentations,
and penicillin is produced by P.notatum and
P.chrysonegum,Some reproduce sexually
by ascospore formation,Penicillia have
septate vegetative mycelium,Conidia,
yeasts
Morphological characteristics
Reproduction
Characteristics of colony
Typical species of yeasts
Morphological characteristics
Yeasts are usually unicellular,Yeast cells
are larger than most bacteria,1-5 um in
width and 5-30 um or more in length,They
are commonly egg-shaped,Yeasts have no
flagella,
Asexual reproduction is by budding or
binary fission; Sexual reproduction is by
forming ascospore.
Saccharomyces,There are about 30
species,S.cerevisiae are used in the
fermentation of beer and wine and in
baking,Budding and 4 ascospores.
Schizosaccharomyces,binary fission
and 8 ascospores,Some species are
used in the fermentation of beer.
Typical species of yeasts
cell structure and characteristics of algae
Algae cells are eukaryotic,single cells
or multicellular,Algae contain
chlorophyll and are photosynthetic.
Algae have a wide range of sizes and
shapes,Some colonies become quite
complex and superficially resemble
higher plants in structure.
The cell wall is thin and rigid,The cell walls
of many algae are surrounded by outer matrix,
which often becomes pigmented and stratified,
Chloroplasts,There are 5 chlorophylls,a,b,
c,d,and e,Chlorophyll a is present in all
algae,
simple sexual reproduction or asexual
reproduction (many algae produce flagellated
spores and/or non motile spores in sporangia).
Typical species of algae
Chlorella,green algae,unicellular
Spirogyra(水绵 ),green algae,
filamentous form,The walls of the filament
are continuous,The chloroplasts of
Spirogyra form a spiral within the filaments,
Diatoms (硅藻 ),golden brown in color,
They have two overlapping halves; one is
larger another is small.
Red algae,exhibit tissue differentiation
and should be classified as plants,
They contain phycocyanin (藻蓝蛋白 )
and phycoerythrin (藻红蛋白 ) in addition
to chlorophyll,The red color is due to
the phycoerythrin,
Roles of Algae in Nature
Algae are an important part of any aquatic food chain
because they fix carbon dioxide into organic molecules
that can be consumed by chemoheterotrophs.
Seasonal changes in nutrients,light,and temperature
cause fluctuations in algal populations; periodic
increases in numbers of algae are called blooms.
Blooms of a few species indicate that the water in
which they grow is polluted
cell structure and characteristics of protozoa
Protozoa are unicellular nonphotosythetic
eukaryotic microorganisms,They generally
lack cell walls,There are 65000 species of
protozoa.
Protozoans are mostly aerobic heterotrophs,
although many intestinal protozoans are capable
of anaerobic growth.
Some protozoa have one nucleus,but others
have two or more nuclei.
Most protozoa reproduce asexually,most
often by binary fission,Some protozoa also
exhibit sexual reproduction,usually by
conjugation.
typical species of protozoa
Euglena (眼虫 )：
Amoeba(变形虫 ):
Parameicium(草履虫 ):
Plasmodium (疟原虫 ):
Eukaryotic Microorganisms
Molds
Mushrooms Fungi
Yeasts
Algae
Protozoa
Eukaryotic Microorganisms
Major differences among fungi,algae and protozoans
Fungi are heterotrophic eukaryotic microorganisms,
They are nonphotosynthetic and typically form
reproductive spores.
Algae are phototrophic eukaryotes that contain
photosynthetic pigments within a structure called the
chloroplast
Protozoa are animallike protists exhibiting
heterotrophic nutrition and they can be defined as
usually motile eukaryotic unicellular microorganisms.
The morphology
Reproduction
Classification
Typical species
Fungi
Fungi
1,Filamentous fungi
2,Unicellular fungi
The morphology of filamentous fungi
The filamentous fungi consists of two pats,the
mycelium and the spores.
The filamentous fungi develop multicellular
branching structures known as hyphae,which are
connected filaments of vegetative cells,Integrated
masses of hyphae are called a mycelium.
Each hypha is about 5-10 um wide.
(1)nonseptate; (2)septate
Reproduction
Asexual spores are formed by the aerial mycelium of
one organism,When these spores germinate,they
become organisms that are genetically identical to the
parent,
Sexual spores result from the fusion of nuclei from
two opposite mating strains of the same species of fungus,
Organisms that grow from sexual spores will have genetic
characteristics of both parental strains,
Asexual spores are produced by an individual
fungus through mitosis and subsequent cell division;
there is no fusion of the nuclei of cells,Several types
of asexual spores are produced by fungi,
Asexual Spores
Asexual spores
Sporangiospores（孢囊孢子）
Conidiospores（分生孢子）
Arthrospores or Oidia（节孢子）
Chlamydospores（厚壁孢子）
Sporangiospore
Sporangiospores are formed
within a sporangium
Rhizopus (class Zygomycetes),These are
common bread molds,which cause much food
spoilage,They have nonseptate,It forms rootlike
hyphae called rhizoid,as well as stolons,
Zygospores are produced when plus and minus
strains are both present.
Sporangiospore
rhizoid
Chlamydospores are thick-walled cells
within the hyphae
Chlamydospores
Arthrospores
Conidiospores
Conidiospores are
arranged in chains at the
end of a conidiophore
Conidiospores
A fungal sexual spore results from sexual reproduction,
consisting of three phases:
1,A haploid nucleus of a donor cell (+) penetrates
the cytoplasm of a recipient cell (Plasmogamy).
2,The (+) and (-) nuclei fuse to form a diploid
zygote nucleus (Karyogamy).
3,By meiosis,the diploid nucleus gives rise to
haploid nuclei (sexual spores),some of which may
be genetic recombinants (Meiosis).
Sexual Spores
The method of a serial dilutions for viable counting
Chlamydospore External Mucor racemosus
arthrospore External Geotrichum candidum
Conidiospore External Aspergillus niger
Penicillium notatum
Sporangiospore Internal Rhizopus oryzae
Asexual spores of filamentous fungi
Name of fungus Location of spores Examples
Several types of sexual spores
Oospores（卵孢子）
Zygospores（接合孢子）
Ascospores（子囊孢子）
Basidiospores（担孢子）
The major classes of fungi
Oomycetes
Zygomycetes
Ascomycetes
Basdiomycetes
Deuteromycetes
Fungi hyphae representives Sexual spore
Zygomycetes Non -septate Mucor; Rhizopus Zygospore
Ascomycetes Septate Neurospora;
Saccharomyces
Ascospore
Basidiomyctes Septate Agaricus;
amanita
Basidiospore
Deuteromycetes Septate Aspergillus;
Penicillium
Not found
Classification and major properties of fungi
Oospores （ 卵 胞子）,these are formed within a
special female structure,the oogonium(藏卵器 ),
Fertilization of eggs,or oospheres (卵 球 ),by
male gametes in an antheridium (雄器 ) give rise
to oospores.
antheridium
oospheres
oospores
oogonium
Oospores
formation
Zygospores are large,
thick-walled spores
formed when the tips of
two sexually compatible
hyphae of certain fungi
fuse together.
Zygospores
Ascospores,these single-celled spores are
produced in a sac called an ascus,There are
usually 8 ascospores in each ascus.
various ascocarps formed by different ascomycete fungi.
plectocarp pyrenocarp discocarp
Ascospores formation,1,yeast 2,Neurospora
Basidiospores,These single-celled
spores are borne on a club-shaped
structure called basidium.
Basidiospores
Mushroom
Fungi usually grow better in an acidic pH (5.0),which is too
acidic for the growth of most common bacteria.
Most molds are aerobic,so they grow on surfaces rather
than throughout a substrate,Yeasts are facultative anaerobes.
3,Most fungi are more resistant to osmotic pressures than
bacteria are; most fungi are therefore able to grow in high sugar or
salt concentrations.
4,Fungi are capable of growing on substances with a very
low moisture content,generally too low to support the growth of
bacteria.
5,Fungi require somewhat less nitrogen for growth than
bacteria.
Fungi are capable of using complex carbohydrates,such as lignin
(wood),that most bacteria cannot metabolize,
1,Fungi usually grow better in an acidic pH (5.0),
which is too acidic for the growth of most common
bacteria,
2,Most molds are aerobic,so they grow on surfaces
rather than throughout a substrate,Yeasts are facultative
anaerobes,
3,Most fungi are more resistant to osmotic pressures
than bacteria are; most fungi are therefore able to grow in
high sugar or salt concentrations.
Fungi differ from bacteria in certain
environmental requirements and in the following
nutritional characteristics:
4,Fungi are capable of growing on substances with a
very low moisture content,generally too low to support
the growth of bacteria.
5,Fungi require somewhat less nitrogen for growth than
bacteria.
6,Fungi are capable of using complex carbohydrates,
such as lignin (wood),that most bacteria cannot
metabolize.
Classification of fungi
The classification of fungi,unlike that of
bacteria,is based primarily on the
characteristics of the sexual spores and
fruiting bodies present during the sexual
stages of their life cycles.
However,the perfect life cycle of many
fungi are yet unknown,They are placed in a
special class of Deuteromycetes.
Typical species of filamentous fungi
Mucor (class Zygomycetes),occur
abundantly in soil and on fruits,
vegetables and starchy foods,Some are
used in the manufacture of cheeses,Their
mycelium are nonseptate and are white or
gray,Zygospores are produced when plus
and minus strains are both present,No
stolons or rhizoids.
Rhizopus (class Zygomycetes),These are
common bread molds,which cause much
food spoilage,They have nonseptate,It
forms rootlike hyphae called rhizoid,as
well as stolons,Zygospores are produced
when plus and minus strains are both
present.
Neurospora (Class Ascomycetes),This
genus is widely used in the study of
genetics and metabolic pathways,Two
well-known species are N,Crassa and N,
Sitophila,Some species are responsible
for food spoilage,and some species are
used in industrial fermentations,Certain
species produce ascospores,conidia is
usually oval,Because of the characteristic
pink or red color of the conidia,they are
often called pink bread molds.
Agaricus (Class Basidiomycetes),The
best known species is A,campestris,the
field mushroom and A,bisporus,the
cultivated mushroom,Most of the larger
species of Agaricus are edible.
Aspergillus (Class Deuteromycetes),The
aspergilli are widespread in nature,Some
species are involved in spoilage,They are
important economically because they are
used in a number of industrial fermentations,
including the production of the citric acid and
gluconic acid,A.niger,The aspergilli
produce septate,branching mycelium,
Conidia,the colors are black,brown,and
green.
Penicillium (Class Deuteromycetes ),
Members of them occur widely in nature
Some species cause rot or other spoilage,
Some are used in industrial fermentations,
and penicillin is produced by P.notatum and
P.chrysonegum,Some reproduce sexually
by ascospore formation,Penicillia have
septate vegetative mycelium,Conidia,
yeasts
Morphological characteristics
Reproduction
Characteristics of colony
Typical species of yeasts
Morphological characteristics
Yeasts are usually unicellular,Yeast cells
are larger than most bacteria,1-5 um in
width and 5-30 um or more in length,They
are commonly egg-shaped,Yeasts have no
flagella,
Asexual reproduction is by budding or
binary fission; Sexual reproduction is by
forming ascospore.
Saccharomyces,There are about 30
species,S.cerevisiae are used in the
fermentation of beer and wine and in
baking,Budding and 4 ascospores.
Schizosaccharomyces,binary fission
and 8 ascospores,Some species are
used in the fermentation of beer.
Typical species of yeasts
cell structure and characteristics of algae
Algae cells are eukaryotic,single cells
or multicellular,Algae contain
chlorophyll and are photosynthetic.
Algae have a wide range of sizes and
shapes,Some colonies become quite
complex and superficially resemble
higher plants in structure.
The cell wall is thin and rigid,The cell walls
of many algae are surrounded by outer matrix,
which often becomes pigmented and stratified,
Chloroplasts,There are 5 chlorophylls,a,b,
c,d,and e,Chlorophyll a is present in all
algae,
simple sexual reproduction or asexual
reproduction (many algae produce flagellated
spores and/or non motile spores in sporangia).
Typical species of algae
Chlorella,green algae,unicellular
Spirogyra(水绵 ),green algae,
filamentous form,The walls of the filament
are continuous,The chloroplasts of
Spirogyra form a spiral within the filaments,
Diatoms (硅藻 ),golden brown in color,
They have two overlapping halves; one is
larger another is small.
Red algae,exhibit tissue differentiation
and should be classified as plants,
They contain phycocyanin (藻蓝蛋白 )
and phycoerythrin (藻红蛋白 ) in addition
to chlorophyll,The red color is due to
the phycoerythrin,
Roles of Algae in Nature
Algae are an important part of any aquatic food chain
because they fix carbon dioxide into organic molecules
that can be consumed by chemoheterotrophs.
Seasonal changes in nutrients,light,and temperature
cause fluctuations in algal populations; periodic
increases in numbers of algae are called blooms.
Blooms of a few species indicate that the water in
which they grow is polluted
cell structure and characteristics of protozoa
Protozoa are unicellular nonphotosythetic
eukaryotic microorganisms,They generally
lack cell walls,There are 65000 species of
protozoa.
Protozoans are mostly aerobic heterotrophs,
although many intestinal protozoans are capable
of anaerobic growth.
Some protozoa have one nucleus,but others
have two or more nuclei.
Most protozoa reproduce asexually,most
often by binary fission,Some protozoa also
exhibit sexual reproduction,usually by
conjugation.
typical species of protozoa
Euglena (眼虫 )：
Amoeba(变形虫 ):
Parameicium(草履虫 ):
Plasmodium (疟原虫 ):
