Microbiology Chapter 17.txt

Molds grow as long, tangled filaments of cells in visible colonies

Yeasts are unicellular fungi

Most fungi (except yeasts) exist as hyphae

A mycelium is a thick mass of hyphae

• Cellulose
• Chitin
• Fungal cell walls are composed of chitin

In many species, septa divide the cytoplasm into separate cells

Growing at filamentous molds or as unicellular pathogens

• Eat food
• Fungi absorb preformed organic matter so they are called heterotrophs

Feeding on dead or decaying organic matter

Live on skin

Hyphae containing many nuclei are considered coenocytic

• Most fungi are aerobic
• Most fungi grow best at around room temperature

• 20-25C - Slow growth, mold like appearance.
• 37C - Colony form, yeast like

• Different shapes at different temps
• Some fungal species may actually have both a mold and yeast life cycle stage
• This ability is largely determined by temperature, but it is also influenced by other factors such as levels of oxygen and nutrients.
• True fungal pathogens to humans are dimorphic.

Many fungi thrive at slightly acidic pH (pH 5-6)

Sabouraud Dextrose Agar

Fungi take up nutrients through absorption

• No genetic diversity
• Sporangiospores
• Conidiaspores
• Arthrospores
• Blastospores
• Chlamydiospores

• Genetic diversity
• Fusion of cells/hyphae
• Heterokaryon
• Fusion of nuclei
• Zygote
• Meiosis
• Spore-producing structure
• Spores
• Germination

Sporulation occurs in fruiting bodies

• Asexual reproductive structures develop at the ends of specialized hyphae
• Many asexual spores (sporangiospores) develop in sacs called sporangia

• Penicillium and Aspergillus possessing septate hyphae and produce conidia (asexual spores) at the end of aerial hyphae called conidiophores
• Conidia form as unprotected spores on conidiophores

• Sporangiospores develop in sacs called sporangia
• The sporangia located at the end of aerial hyphae are called sporangiophores.
• Rhizopus has nonseptate hyphae and produce asexual sporangiospores within a sac called the sporangium.

Large spores

• Fragmentation of hyphae yields arthrospores
• The ends get thick and break off
• Athlete's foot

• In budding, a blastospore develops from the parent cell
• Yeast

Opposite mating types come together and fuse into a heterokaryon

• Division I: Eumycota
• Class 2: Zygomycetes
• Class 3: Ascomycetes
• Class 5: Deuteromycetes

• Form a zygospore
• Zygomycetes are terrestrial fungi that grow as mold on bread and produce
• In asexual reproduction, they produce a sporangiaspores
• During sexual reproduction, they form a heterokaryotic, diploid zygospore

• Conidia through asexual reproduction
• Ascospores through sexual reproduction

• Baker�s yeast
• The mold that produces penicillin
• The fungus that produces aflatoxin
• Candida albicans, the cause of thrush, diaper rash, and vaginitis

• Basidiomycetes are club fungi, including mushrooms and puffballs
• Some form mycorrhizae
• Others are plant pathogens
• Basidia on the gills of a mushroom cap contain sexually-produced basidiospores

• No known sexual reproduction
• Imperfect fungi

• Produces CO2 or alcohol
• Reproduces by budding
• Has lots of B vitamins

• In orchards
• Wine yeasat

Any Single-Celled Stage of a Fungus

Ferment sugars

• They are used in bread backing and alcohol production
• S. cerevisiae is a model eukaryotic organism

Moldy skin

Feet

Head

Body

Groin

Nails

Haired portion of the head and face

A fungal infection of the body surface

Include blister-like lesions with a thin fluid discharge

• Often involves changing the skin environment (moisture, pH, etc.)
• Keep skin dry
• Vinegar & Honey
• Cigar Ash

dermatophytosis (tinea infections/ringworm) on the skin, hair, nails

• Domestic animals
• Fomites like:
• floors
• mats
• towels

• Tricophyton
• Microsporium
• Epidermophyton

• An immune reaction showing symptoms of fungal infection elsewhere on the body.
• When the sight is cultured, there is no fungus there.

• 33% in the US have this on their skin
• Candidiasis Often Is a Mild, Superficial Infection

• The immune system is compromised or
• Microbial populations in the body change

• Often called a �yeast infection,� involves
• itching
• burning
• reddening
• swelling
• Discharge

Decrease protective bacteria in the vagina and intestine, allowing C. albicans to flourish

• Vulvovaginitis (yeast infection)
• Oral candidiasis (thrush)
• Onychia, a brownish thickening of the nails

• Gentian violet
• Nystatin

• Sporothrix schenkii
• Rose thorn disease
• Infection with spores can cause pus-filled lesions
• Get when immune system isn't working

• Sporotrichosis Is an Occupational Hazard
• wood
• wood products
• soil

• Poked with a rose thorn
• Peat moss
• Splinters

Amphotericin B

• Found in pigeon droppings
• Affects lungs and meninges
• Commonly seen in AIDS patients
• Cells can (rarely) pass into the bloodstream, infecting the brain and meninges

• Headache
• Stiff neck
• Possible paralysis

Amphotericin B

Damages kidneys

• It is caused by Histoplasma capsulatum
• It is found in dry, dusty soil, chicken coops, and bat caves
• Most people suffer only mild influenza-like symptoms
• Darling�s disease

Inhaling dust

• Summer flu
• Occasionally nodules in the lungs
• Looks just like TB in XRay

If nodules in the lungs, Amphotericin B, otherwise clears without help

• It is caused by Blastomyces dermatitidis
• Gilchrist�s disease

• Blastomycosis Usually Is Acquired Via the Respiratory Route
• It is associated with dusty soil and bird droppings

• Lung lesions
• Persistent cough
• Chest pains
• It can cause chronic pneumonia and may disseminate to other organs in AIDS patients

Amphotericin B

• It is commonly caused by Aspergillus fumigatus
• In aspergillosis, conidia enter the body and grow as a mycelium

Surgery may be necessary to remove an aspergilloma from the lungs

Otomycosis in the ear, which can affect the heart

Beano� to reduce flatulence

Inhaling a spore

Amphotericin B

• Aspergilloma
• Otomycosis

• Aflatoxin: Aspergillus flavus
• Mycotoxins
• A. flavus and A. parasiticus produce carcinogenic aflatoxins
• Aflatoxins contaminate many agricultural products
• Can eat through the skin

Ergotism is caused by Claviceps purpurea, which grows on Rye, Wheat, Barley

Ingestion

• numbness
• hot and cold sensations
• seizures
• paralysis of nerve endings

• Pitosin
• Lysergic acid diethylamide (LSD) is a derivative of an alkaloid in ergot

mutualistic association between a fungus (frequently an ascomycete) and a photosynthetic organism

• It is caused by Pneumocystis jiroveci
• It is a common infection in AIDS patients
• P. jiroveci has a complex life cycle in the alveoli
• It is usually transmitted through respiratory droplets

Fungi that grow as long, tangled filaments of cells that give rise to visible colonies.

• Intertwined filaments of mold.
• The morphological (structural) unit of filamentous fungi

• A thick mass of hyphae
• Usually large enough to be seen with the unaided eye and generally has a rough, couttony texture.

• A carbohydrate polymer of actylglucosamine units
• Composes a large amount of the cell wall

Walls that separate the hyphal cytoplasm into separate cells

Hyphae contains many nuclei in a common cytoplasm

Fungi that grow as filamentous molds at room temperature (25C) and convert to unicellular, pathogenic yeast-like forms at body temperature (37C)

Laboratory media containing extra glucose for growing molds and yeasts

A symbiotic relationship between two organisms of different species that benefits both.

• Live harmoniously with plants where the hyphae invade or envelop the roots of plants.
• They consume some of the carbs produced by the plants
• Contribute essential minerals and water to the plants

Part of the fungus where spores are formed and from which they are released.

Spores produced in sacs called sporangia

Spores produced on the supportive structures called conidia. These spores are unprotected, are very light and blown on wind currents.

• Spores that form by fragmentation of the hyphae.
• Athlete's foot fungus multiplies in this manner

A new yeast cell formed by budding.

• Fungi produced by sexual reproduction
• The nuclei are different from each parent
• Hetero = different
• Karyo = nucleus

The oldest known fungi belonging to the phylum Chytridiomycota

• Formed during sexual reproduction between Zygomycota.
• Opposites fuse forming a unique, heterokaryotic, diploid zygospore

A member ascomycota phylum, lichen is a mutualistic association between a fungus and a photosynthetic organism.

Club fungi members of the Basidiomycota phylum

Oral candidiasis

The feeding stage of Pneumocytstis jiroveci swells to become a precyst stage

Toxins produced my fungi