IV. Fungi KNOW RED STUFF

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IV. Fungi KNOW RED STUFF A. Overview
1. General Characteristics - multicellular
eukaryotes - heterotrophic - absorptive
nutrition excrete enzymes into environment and
absorb the product of that digestion. They
digest dead matter (decomposers) or live matter
(pathogens), or may be symbiotes.
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IV. Fungi 2. Classification -
Chytridiomycota - Zygomycota - Ascomycota -
Basidiomycota Single celled members of these
groups are all called yeasts. They are
distinguished from protists based on a chitinous
cell wall and absorptive (rather than phagocytic)
nutrition.
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IV. Fungi 3. General Biology - The organism
is composed of threadlike hyphae
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IV. Fungi 3. General Biology - The organism is
composed of threadlike hyphae - The hypha can
be coenocytic (without divisions) or septate
(with incomplete cell walls between)
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IV. Fungi 3. General Biology - The organism is
composed of threadlike hyphae - The hypha can
be coenocytic (without divisions) or septate
(with incomplete cell walls between) - These
have a huge surface area/volume ratio for
absorption. - The largest organisms known 37
acres.
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IV. Fungi 4. Ecological Roles - decomposers
Fungi decompose lignin and cellulose, which most
free-living bacteria cant digest.
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IV. Fungi 4. Ecological Roles - decomposers
Fungi decompose lignin and cellulose, which most
free-living bacteria cant digest.
antibiotics
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IV. Fungi 4. Ecological Roles - decomposers
Fungi decompose liginin and cellulose, which most
free-living bacteria cant digest.
antibiotics - mycorrhizae fungal symbiotes of
certain plants. The fungus increases the
absorbance area of roots dramatically, and passes
water and nutrients to the plant. The plant
feeds the fungus with glucose.
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IV. Fungi 4. Ecological Roles - decomposers
Fungi decompose liginin and cellulose, which most
free-living bacteria cant digest.
antibiotics - mycorrhizae fungal symbiotes of
certain plants. The fungus increases the
absorbance area of roots dramatically, and passes
water and nutrients to the plant. The plant
feeds the fungus with glucose. - lichens
symbiote with alga
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IV. Fungi 4. Ecological Roles - decomposers
Fungi decompose liginin and cellulose, which most
free-living bacteria cant digest.
antibiotics - mycorrhizae fungal symbiotes of
certain plants. The fungus increases the
absorbance area of roots dramatically, and passes
water and nutrients to the plant. The plant
feeds the fungus with glucose. - lichens
symbiote with alga - pathogens Athletes foot,
ringworm, yeast infections - parasites
entomophagous fungi
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IV. Fungi B. Zygomycetes - coenocytic hypha
- asexual reproduction haploid hypha produces
sporangia and releases spores.
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IV. Fungi B. Zygomycetes - sexual
reproduction hypha touch, and produce
gametangia. Gametes produced inside fusion
into dikaryotic cells (2 nuclei). Each dikaryon
then becomes diploid (fusion of nuclei and
undergoes meiosis. Spores are released. - many
are imporant mycorrhyzal symbionts.
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IV. Fungi C. Ascomycetes - septate hypha
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IV. Fungi C. Ascomycetes - septate hypha -
characterized by production of spore-bearing
asci
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IV. Fungi C. Ascomycetes - septate hypha -
characterized by production of spore-bearing
asci - bakers yeast (levening and
fermentation) - molds pathogens of plants such
as Aspergillus, Penicillium, Neurospora, Chestnut
Blight, Dutch Elm disease, etc.
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IV. Fungi C. Ascomycetes - life cycle
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IV. Fungi D. Basidiomycetes - bear puffballs
or mushrooms as fruiting bodies
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IV. Fungi D. Basidiomycetes - bear puffballs
or mushrooms as fruiting bodies - haploid hyphae
fuse in dikaryotic hyphae.
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IV. Fungi D. Basidiomycetes - bear puffballs
or mushrooms as fruiting bodies - haploid hyphae
fuse in dikaryotic hyphae. - these dikaryotic
hyphae form the fruiting structure.
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IV. Fungi D. Basidiomycetes - bear puffballs
or mushrooms as fruiting bodies - haploid hyphae
fuse in dikaryotic hyphae. - these dikaryotic
hyphae form the fruiting structure. - at the tip
of each hyphae, the basidium forms, in which
meiosis occurs to produce new haploid spores.
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- life cycle
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Characteristics of Fungal HyphaeSeptate versus
Coenocytic
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Mycelium Large, Visible Mass of Hyphae
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• IMPORTANT DIVISIONS OF FUNGI
• 1. Deuteromycota
• Not known to produce sexual spores.
• Reproduce asexually.
• Catch-all category for unclassified fungi
• Pneumocystis carinii Causes pneumonia in AIDS
  patients. Leading cause of death in AIDS
  patients. Originally classified as a protozoan.
• Candida albicans Causes yeast infections of
  vagina in women. Opportunistic infections of
  mucous membranes in AIDS patients.

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Opportunistic Infection by Candida albicans in an
AIDS Patient
Source Atlas of Clinical Oral Pathology, 1999
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Life Cycle of Eupenicillium (Ascomycete)Reproduce
s Asexually and Sexually
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Severe nail infection with Trichophyton rubrum
in a 37-year-old male AIDS patient. Source
Intern. J. Dermatol. 31(1992) 453.
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Disseminated Histoplasma capsulatum, skin
infection. Source Microbiology Perspectives,
1999.
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• FUNGAL DISEASES
• Mycosis Any fungal disease. Tend to be chronic
  because fungi grow slowly.
• Mycoses are classified into the following
  categories
• I. Systemic mycoses Fungal infections deep
  within the body. Can affect a number if tissues
  and organs.
• Usually caused by fungi that live in the soil and
  are inhaled. Not contagious.
• Examples
• Histoplasmosis (Histoplasma capsulatum) Initial
  infection in lungs. Later spreads through blood
  to most organs.
• Coccidiomycosis (Coccidioides immites)
  Resembles tuberculosis.

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Systemic Mycosis Histoplasmosis
Disseminated Histoplasma capsulatum, lung
infection. Source Microbiology Perspectives,
1999.
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• FUNGAL DISEASES (Continued)
• II. Cutaneous mycoses Fungal infections of the
  skin, hair, and nails.
• Secrete keratinase, an enzyme that degrades
  keratin.
• Infection is transmitted by direct contact or
  contact with infected hair (hair salon) or cells
  (nail files, shower floors).
• Examples
• Ringworm (Tinea capitis and T. corporis)
• Athletes foot (Tinea pedis)
• Jock itch (Tinea cruris)

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Cutaneous Mycosis
Ringworm skin infection Tinea corporis Source
Microbiology Perspectives, 1999
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Cutaneous Mycosis
Candida albicans infection of the nails. Source
Microbiology Perspectives, 1999.
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• FUNGAL DISEASES (Continued)
• III. Subcutaneous mycoses Fungal infections
  beneath the skin.
• Caused by saprophytic fungi that live in soil or
  on vegetation.
• Infection occurs by implantation of spores or
  mycelial fragments into a skin wound.
• Can spread to lymph vessels.
• IV. Superficial mycoses Infections of hair
  shafts and superficial epidermal cells.
  Prevalent in tropical climates.

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• FUNGAL DISEASES (Continued)
• Opportunistic mycoses Caused by organisms that
  are generally harmless unless individual has
  weakened defenses
• AIDS and cancer patients
• Individuals treated with broad spectrum
  antibiotics
• Very old or very young individuals (newborns).
• Examples
• Aspergillosis Inhalation of Aspergillus spores.
• Yeast Infections or Candidiasis Caused mainly
  by Candida albicans. Part of normal mouth,
  esophagus, and vaginal flora.

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• ECONOMIC IMPORTANCE OF FUNGI
• 25-50 of harvested fruits and vegetables are
  damaged by fungi.
• Fungal infections of plants are commonly called
  rots, rusts, blights, wilts, and smuts.
• Phytophthora infestans Caused great potato
  famine in mid-1800s. Over 1 million people died
  from starvation in Ireland. Many immigrated to
  the U.S.
• Beneficial fungi
• Candida oleophila Prevents fungal growth on
  harvested fruits.
• Saccharomyces cerevisiae Used to make bread and
  wine.
• Genetically engineered yeast strains are used to
  make proteins (Hepatitis B vaccine).
• Taxomyces Produces anticancer drug taxol.
• Trichoderma Produces cellulase. Used to make
  fruit juice.