Mycology

2 roles of saprophytic fungi

Decomposer of organic waster

Producers of antibiotics (metabolic waste that is toxic to other organisms)

Fungi are … pathogens

Never obligate => they can always obtain nutrients from dead organisms

Fungi can be divided in

Yeast (unicellular)

Moulds (multicellular)

What’s a dimorphic fungi?

Fungi that exist as mould in the environment and as yeast in human and animals tissues at body temperature.

They take the form of yeast cells in the parasitic stage and appear as mycelia in the saprophytic phase

What’s a mycelia

A mass of molds’ hyphae

Yeast reproduction method

Reproduce asexually by mitosis or by mitosis with budding

Or sexually (in some sp.) under certains conditions, forms sexual spores (ascospores or basidiospores), involving meiosis

What are hyphae

Branching filaments of moulds

Hyphal cell description

• One or two nucleus

• Many are separated by septa with pores that allow cytoplasm and nucles to travel from cell to cell

Hyphae classification

Septate

Nonseptate (multinucleated)

2 types of mycelium

• Vegative: part that anchors the mould and absorb nutrient

• Aerial: Part that project above the surface of the culture, some produce spore (reproductive hyphae)

How mould reproduce

Asexual

• Hyphal growth and tip extension

• Fragmentation of part of hyphae

• Asexual spores (conidia or sporangiospores)

Sexual

• With sexual spore (under certain env conditions)

• Sexual spore are produced by specialized sexual structues that produce spors like ascospores or zygospores = bring genetic diversity

Dermatophytes are

Moulds that use keratin for growth

What contains most of fungi’s cell wall

Chitin

Fungal cell membrane contains…

Ergosterol (equivalent of cholesterol in vertebrates)

Fungal ribosomes

80s

How fungi deal with nutrients

They’re heterotroph, they absorb nutrient from envrinoment and stock it in the form of glycogen

Fungal chromosomes

Linear

Fungal organelles

Contain membrane-bound organelles (e.g, mitochondria)

How perfect and imperfect fungi reproduce

Perfect: asexual & sexual

Imperfect: asexual (mitosis) only

Reproductive state of fungi

Anamorph = asexual stage

Teleomorph = sexual

=> Anamorph + teleomorph = holomorph

Spores difference between yeast and mould

Yeast: always unicellar

Mould: can be unicellular or multicellular

Fungal diseases

Mycoses (infection)

Fungal allergies (spores can contain allergens)

Mycotoxicosis (ingestion of fungal toxins)

Mycetoma (invasive infection, usually after implatation of a foreign body in the skin)

Why antibiotics don’t work on fungi

Bacteria = prokaryotic

Fungi = eukaryotic

List few mechanism of actions of antifungal

• Mitosis inhibition

• Inhibition of cell wall synthesis

• Inhibtion of DNA and protein synthesis

• Inhibition of ergosterol synthesis

• Binding to membrane sterols