Mycology

Fungi

mykes

Fungi

a general term for a group of eukaryotic organisms (mushroom, mold, yeast) marked by the absence of chlorophyll (non-photosynthetic), the presence of a rigid cell wall in some

stage of the life cycle.

Fungi

May be aerobic or facultative anaecrobic

obligate anaerobic

No __ fungi are known

Fungi

Majority are saprophytes in soil and water;

Fungi

they primarily decompose plant material, but

some are parasitic

rigid cell wall

the presence of a ___ in some stage of the life cycle.

HETEROTROPHS

Mode of nutrition:Fungi

Fungi

Produce digestive enzymes and obtain nutrients by absorption

Saprophytes (Saprotrophs) and Parasites

HETEROTROPHS compose of

Saprophytes (Saprotrophs)

Dead organisms or their wastes (dung)

Parasites

Living cells of other fungi, plants or animals

1\. Molds and Fleshy Fungi

2\. YEASTS

3\. Dimorphic Fungi

Enumerate forms of fungi

Molds and Fleshy Fungi

appear like tuft of cotton, or a sooty black patch, or a fuzzy or powdery mass & sometimes variously colored

Molds and Fleshy Fungi

often found growing on old, moist bread, jellies, fruits or other foods or appearing as contaminants in laboratory culture media with a characteristic “moldy” smell.

Molds and Fleshy Fungi

with a characteristic “moldy” smell.

Molds and Fleshy Fungi

Prefer neutral (pH 7.0) but can tolerate pH 2.0 (very acidic) to pH 8.0 (alkaline)

Prefer neutral (pH 7.0) but can tolerate pH 2.0 (very acidic) to pH 8.0 (alkaline)

Molds and Fleshy Fungi prefer neutral __*___*__ but can tolerate pH ___ to ph ____

Molds and Fleshy Fungi

Prefer room temperature but can grow at freezing temperatures

molds

Some ___ produce toxins that can cause illness.

Thallus (Colony)

Mycelium

Hyphae

Structure of a Mold or Fleshy Fungi

Thallus (Colony)

Body of the mold or fleshy fungi

Mycelium

filamentous tangled mass or tissue like aggregation formed by

growing hyphae

Hyphae

Greek “web”

Hyphae

Basic filamentous unit of structure of the fungi

Hyphae

Relatively coarse threads or ribbon-like, having an average width of

about 4um

Vegetative hypha

Reproductive hypha/Acrial hypha

Divisions of hyphae:

Vegetative hypha

portion of a hypha that obtains nutrients

Reproductive hypha/Aerial hypha

portion concerned with reproduction; often bear reproductive spores

Septate Hyphae

Coenocytic Hyphae

2 types of Hyphae:

Septate Hyphae

Hyphae with septa

SEPTA (SEPTUM)

In most molds, the hyphae contain cross-walls called__ which divide them into distinct, uninucleate (one-nucleus) cell-like units.

Coenocytic Hyphae

Hyphae without septa

Yeast

non-filamentous, unicellular fungi that are typically spherical or oval

Yeast

Like molds, they are widely distributed in nature;

Yeast

frequently found as powdery coating on fruits and leaves

Yeast

capable of facultative anaerobic growth

Yeast

can use oxygen or an organic compound as the final electron acceptor; this is avaluable attribute because it allows these fungi to survive in various environments.

Yeast reproduce by means of

BUDDING

2 Types of Yeasts:

Budding Yeast

Fission Yeast

Fission Yeast

The parent cell starts to elongate

Fission Yeast

It’s nucleus divides and two offspring cells are produced

Fission Yeast

Increases in number of yeast cells on a solid medium, produce a colony

similar to bacterial colony.

Budding Yeast

The parent cell forms a protuberance (bud) on its outer surface

Budding Yeast

As the bud elongates, the parent cell’s nucleus divides and one nucleus

migrate into the bud.

Budding Yeast

Cell wall materials is then laid down between the bud and parent cell,

and the bud eventually breaks away.

PSEUDOHYPHA

Some yeasts produce buds that fail to detach themselves, these buds

form a short chain of cells called

PSEUDOHYPHA

Occurs under appropriate conditions

Dimorphic Fungi

Fungi that appear as both yeast-like and mold-like at different phases of their growth

Histoplasma and Coccidioides spp.

Common among disease-producing fungi such as

Temperature-dependent: of yeast-like

37°C

Temperature-dependent: of mold-like

25°C

Examples: Dimorphic Fungi

Histoplasma capsulatum, Blastomyces dermatitidis, Coccidioides immitis

Types of Fungal Reproduction

Asexual Reproduction

Sexual Reproduction

Asexual Reproduction

Fragmentation of specialized, differentiated parts (aerial hyphae) of thallus

Sexual Reproduction

Occurs in ascus, a sac-like structure and by means of spores formed from the product

of fusion of parent haploid nuclei.

spores.

Both sexual and asexual reproduction occurs by the formation of

spore type

fungi are usually identified by

Spores

Any single, rounded structure which when separated from the parent fungus, is capable of germinating and reproducing the whole organism

asexually

In the more highly organized molds, reproductive spores are formed __ in great

numbers on characteristically differentiated fertile hyphae (aerial hyphae).

special reproductive structure.

In other fungi, spores develop directly from the growing (vegetative) portion of the fungus without any ___

Asexual spores

Formed by the hyphae of one organism.

Asexual spores

When these spores germinate, they become

organisms that are genetically identical to the parent

Types of Asexual spore

Sporangiospores

Conidiospore (Conidia/Conidium)

Sporangiospores

spore borne within a sporangium or sac at the end of an aerial hyphae called sporangiophore (Rhizopus)

sporangiophore (Rhizopus)

spore borne within a sporangium or sac at the end of an aerial hyphae called

Sporangiospores

The spores are formed within the sporangium or sac

Sporangiosperes

Produced by non-septate mycelium

Conidiospore (Conidia/Conidium)

spore that is NOT enclosed in a sac

and bud from conidiophores

Arthroconidia

Conidia formed by the fragmentation of a septate hypha into single, slightly thickened cells (Coccidoides immitis,

Aspergillus)

Arthroconidia

segments pinched off or walled off directly from undifferentiated hyphae

Arthroconidia

Often these are round or cylindrical, rather thick-walled cells are seen still in position in the segmented filament.

Coccidoides immitis,

Aspergillus

Example of Arthroconidia

Blastoconidia

consists of buds coming off the parent cell

Blastoconidia

The buds formed by a process of sprouting from the surface of the parent cell.

Blastoconidia

Budding is the characteristic method by which true yeast multiply

yeasts such as Candida albicans and Cryptococcus

Examples of Blastoconidia

Chlamydoconidium

a thick-walled spore formed by rounding and enlargement within a hyphal segment

Chlamydoconidium

a rounded, swollen portion of a hypha which becomes surrounded by a thick, tough wall. This represents a resting,

encysted part of the fungus, capable of resisting unfavorable

environment.

Candida albicans

Example of Chlamydoconidium

Conidia

asexual spores formed outside of a limiting membrane, born on specialized hyphae (conidiophores) or arising directly from a vegetative mycelium.

Conidia

They are freed from the hyphae by abstraction at the point of attachment.

Macroconidia

Microconidia

Types of Conidia

Macroconidia

Large, multi-celled conidia which are produced by dermatophytes

in culture

Macroconidia

spindle-shaped, or club-shaped bodies, divided into two or more cells by septa.

Macroconidia

characteristic of certain ringworm

fungi.

Microconidia

Small, single-celled conidia which are produced by certain dermatophytes

Sexual spores

result from the fusion of nuclei from two opposite mating strains of the same

species of fungus. Fungi produce sexual spores less frequently than asexual spores.

Sexual spores

will have genetic characteristics of both

parental strains.

Plasmogamy

Karyogamy

Meiosis

A fungal sexual spore results from sexual reproduction, which consists of three

phases:

Plasmogamy.

A haploid nucleus of a donor cell (+) penetrates the cytoplasm of a recipient cell (—).

Karyogamy.

The (+) and (—) nuclei fuse to form a diploid zygote nucleus.

Meiosis.

The diploid nucleus gives rise to haploid nuclei (sexual spores), some of which may be genetic recombinants.

|. Zygospore

2\. Ascospore — Sac Fungi

3\. Basidiospore — Club Fungi

Types of Sexual spore

Zygospore

formed when tips of hyphae come together and their contents fuse with the development of a large thick-walled body

Zygospore

formed when two undifferentiated hyphae fuse from neighboring growths to make a single, round, pigmented structure from which new hyphae develop later.

Zygospore

Fusion of the nuclei may occur from two cells that are morphologically similar to each other

Ascospore

ascus (sac) with definite number of spores

Ascospore

sexual spores are formed within an especially developed closed sac

Ascospore

A rudimentary sexual process involving fusion of the nuclei of the parent cells precedes the actual formation of the ascospores