I. I. FUNGI (Mycology) FUNGI (Mycology) Diverse group of heterotrophs. Diverse group of heterotrophs. Many are ecologically important Many are ecologically important saprophytes saprophytes (consume dead (consume dead and decaying matter) and decaying matter) Others are parasites. Others are parasites. Most are multicellular, but yeasts are Most are multicellular, but yeasts are unicellular. unicellular. Most are aerobes or facultative anaerobes. Most are aerobes or facultative anaerobes. Cell walls are made up of Cell walls are made up of chitin chitin (polysaccharide). (polysaccharide). Over 100,000 fungal species identified. Over 100,000 fungal species identified. Only about 100 are human or animal pathogens. Only about 100 are human or animal pathogens. Most human fungal infections are nosocomial and/or occur in Most human fungal infections are nosocomial and/or occur in immunocompromised individuals (opportunistic infections). immunocompromised individuals (opportunistic infections). Fungal diseases in plants cause over 1 Fungal diseases in plants cause over 1 billion dollars/year in losses. billion dollars/year in losses.
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U I. FUNGI (Mycology) u Diverse group of heterotrophs. u Many are ecologically important saprophytes (consume dead and decaying matter) u Others are parasites.
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I. I. FUNGI (Mycology)FUNGI (Mycology) Diverse group of heterotrophs.Diverse group of heterotrophs.
Many are ecologically important Many are ecologically important saprophytessaprophytes (consume dead and (consume dead and decaying matter)decaying matter)
Others are parasites. Others are parasites.
Most are multicellular, but yeasts are unicellular.Most are multicellular, but yeasts are unicellular. Most are aerobes or facultative anaerobes.Most are aerobes or facultative anaerobes. Cell walls are made up of Cell walls are made up of chitinchitin (polysaccharide). (polysaccharide). Over 100,000 fungal species identified. Only Over 100,000 fungal species identified. Only
about 100 are human or animal pathogens.about 100 are human or animal pathogens. Most human fungal infections are nosocomial and/or occur in Most human fungal infections are nosocomial and/or occur in
Fungal diseases in plants cause over 1 billion Fungal diseases in plants cause over 1 billion dollars/year in losses.dollars/year in losses.
CHARACTERISTICSCHARACTERISTICS OFOF FUNGI FUNGI
1. Yeasts1. Yeasts
Unicellular fungi, nonfilamentous, typically oval or Unicellular fungi, nonfilamentous, typically oval or
spherical cells. Reproduce by mitosis:spherical cells. Reproduce by mitosis: Fission yeastsFission yeasts: Divide evenly to produce two new cells : Divide evenly to produce two new cells
((SchizosaccharomycesSchizosaccharomyces).).
Budding yeastsBudding yeasts: Divide unevenly by budding (: Divide unevenly by budding (Saccharomyces)Saccharomyces)..
Budding yeasts can form Budding yeasts can form pseudohyphapseudohypha, a short chain of , a short chain of
undetached cells.undetached cells.
Candida albicans Candida albicans invade tissues through pseudohyphae.invade tissues through pseudohyphae.
Yeasts are facultative anaerobes, which allows them to Yeasts are facultative anaerobes, which allows them to
grow in a variety of environments.grow in a variety of environments. When oxygen is available, they carry out aerobic respiration.When oxygen is available, they carry out aerobic respiration.
When oxygen is not available, they ferment carbohydrates to produce When oxygen is not available, they ferment carbohydrates to produce
ethanol and carbon dioxide.ethanol and carbon dioxide.
2. Molds and Fleshy Fungi2. Molds and Fleshy Fungi Multicellular, filamentous fungi.Multicellular, filamentous fungi. Identified by physical appearance, colony characteristics, Identified by physical appearance, colony characteristics,
and reproductive spores.and reproductive spores. ThallusThallus: Body of a mold or fleshy fungus. Consists of many : Body of a mold or fleshy fungus. Consists of many
hyphae.hyphae. HyphaeHyphae (Sing: Hypha): Long filaments of cells joined together. (Sing: Hypha): Long filaments of cells joined together.
Septate hyphae:Septate hyphae: Cells are divided by cross-walls (septa). Cells are divided by cross-walls (septa). Coenocytic (Aseptate) hyphaeCoenocytic (Aseptate) hyphae: Long, continuous: Long, continuous cells that cells that
are not divided by septa.are not divided by septa.Hyphae grow by elongating at the tips.Hyphae grow by elongating at the tips.Each part of a hypha is capable of growth.Each part of a hypha is capable of growth.
Vegetative HyphaVegetative Hypha: Portion that obtains nutrients.: Portion that obtains nutrients. Reproductive or Aerial HyphaReproductive or Aerial Hypha: Portion connected with : Portion connected with
reproduction.reproduction. MyceliumMycelium: Large, visible, filamentous mass made up of many : Large, visible, filamentous mass made up of many
hyphae.hyphae.
Characteristics of Fungal Hyphae:Septate versus Coenocytic
1. Deuteromycota1. Deuteromycota Not known to produce sexual spores. Not known to produce sexual spores.
Reproduce asexually.Reproduce asexually.
Catch-all category for unclassified fungi:Catch-all category for unclassified fungi: Pneumocystis cariniiPneumocystis carinii: Causes pneumonia in AIDS : Causes pneumonia in AIDS
patients. Leading cause of death in AIDS patients. patients. Leading cause of death in AIDS patients.
Originally classified as a protozoan.Originally classified as a protozoan.
Candida albicansCandida albicans: Causes yeast infections of vagina in : Causes yeast infections of vagina in
women. Opportunistic infections of mucous women. Opportunistic infections of mucous
membranes in AIDS patients.membranes in AIDS patients.
Opportunistic Infection by Candida albicans in an AIDS Patient
2. Zygomycota (Conjugation Fungi)2. Zygomycota (Conjugation Fungi) Also known as bread molds. Also known as bread molds. Saprophytic molds with Saprophytic molds with coenocyticcoenocytic hyphae (lack septa). hyphae (lack septa). Asexual ReproductionAsexual Reproduction: Used most of the time. : Used most of the time.
SporangiosporeSporangiospore: Asexual spore enclosed within a : Asexual spore enclosed within a sporangiumsporangium or sac at the end on an aerial hypha. or sac at the end on an aerial hypha.
Sexual ReproductionSexual Reproduction: Occurs through : Occurs through conjugationconjugation, the , the joining of hypha of two different strains (plus and minus).joining of hypha of two different strains (plus and minus).
Zygospores:Zygospores: Sexual spores which are enclosed in a thick, Sexual spores which are enclosed in a thick, resistant wall. resistant wall.
Generally not pathogens.Generally not pathogens. Rhizopus nigricansRhizopus nigricans: Common black bread mold. May cause : Common black bread mold. May cause
opportunistic infections in diabetes patientsopportunistic infections in diabetes patients
Life Cycle of a Zygomycete: Black Bread Mold (Rhizopus)Reproduces Asexually and Sexually
Reproductive Structures of Zygomycete (Rhizopus)Sporangia (asexual) and Zygospore (sexual)
IMPORTANTIMPORTANT DIVISIONSDIVISIONS OFOF FUNGIFUNGI3. Ascomycota (Sac Fungi)3. Ascomycota (Sac Fungi) Molds with septate hyphae and some yeasts.Molds with septate hyphae and some yeasts.
Asexual ReproductionAsexual Reproduction: : ConidiosporesConidiospores notnot enclosed in a enclosed in a
sac. Become airborne easily. Form chains (broom-like sac. Become airborne easily. Form chains (broom-like
structures).structures).
Sexual ReproductionSexual Reproduction: : AscosporesAscospores enclosed in a enclosed in a sac-likesac-like
structure (structure (ascusascus).). Include common antibiotic producing fungi and yeasts, Include common antibiotic producing fungi and yeasts,
and several human pathogens.and several human pathogens. Penicillium notatumPenicillium notatum (Produces penicillin)(Produces penicillin) SaccharomycesSaccharomyces (Brewer’s yeast)(Brewer’s yeast) TrychophytonTrychophyton (Athlete’s foot)(Athlete’s foot) AspergillusAspergillus (Carcinogenic aflatoxin in peanuts)(Carcinogenic aflatoxin in peanuts),, BlastomycesBlastomyces (Respiratory infections)(Respiratory infections) Histoplasma capsulatumHistoplasma capsulatum (Respiratory and systemic infections)(Respiratory and systemic infections)
Life Cycle of Eupenicillium (Ascomycete)Reproduces Asexually and Sexually
Severe nail infection with Trichophyton rubrum ina 37-year-old male AIDS patient.Source: Intern. J. Dermatol. 31(1992): 453.
Opportunistic mycosesOpportunistic mycoses: Caused by organisms that are : Caused by organisms that are
generally harmless unless individual has weakened generally harmless unless individual has weakened
defenses:defenses: AIDS and cancer patientsAIDS and cancer patients
Individuals treated with broad spectrum antibioticsIndividuals treated with broad spectrum antibiotics
Very old or very young individuals (newborns).Very old or very young individuals (newborns).
Examples:Examples: AspergillosisAspergillosis: Inhalation of : Inhalation of AspergillusAspergillus spores. spores.
Yeast Infections or Candidiasis:Yeast Infections or Candidiasis: Caused mainly by Caused mainly by Candida Candida
albicansalbicans. Part of normal mouth, esophagus, and vaginal flora.. Part of normal mouth, esophagus, and vaginal flora.
ECONOMIC IMPORTANCE OF FUNGIECONOMIC IMPORTANCE OF FUNGI 25-50% of harvested25-50% of harvested fruits and vegetables are damaged fruits and vegetables are damaged
by fungi.by fungi.
Fungal infections of plants are commonly called rots, Fungal infections of plants are commonly called rots,
rusts, blights, wilts, and smuts.rusts, blights, wilts, and smuts. Phytophthora infestansPhytophthora infestans: Caused great potato famine in mid-: Caused great potato famine in mid-
1800s. Over 1 million people died from starvation in Ireland. 1800s. Over 1 million people died from starvation in Ireland.
Many immigrated to the U.S.Many immigrated to the U.S.
Beneficial fungi:Beneficial fungi: Candida oleophilaCandida oleophila: Prevents fungal growth on harvested fruits.: Prevents fungal growth on harvested fruits.
Saccharomyces cerevisiaeSaccharomyces cerevisiae: Used to make bread and wine. : Used to make bread and wine.
Genetically engineered yeast strainsGenetically engineered yeast strains are used to make proteins are used to make proteins
(Hepatitis B vaccine).(Hepatitis B vaccine).
TaxomycesTaxomyces: Produces anticancer drug taxol.: Produces anticancer drug taxol.
TrichodermaTrichoderma: Produces cellulase. Used to make fruit juice.: Produces cellulase. Used to make fruit juice.