Fungi Mycology is the study of fungi

Fungi Once confused with plants Range in size from single cell to chains of cells miles long Grow in slightly acidic environments Grow in soil, on your body, house, plants, animals. – A teaspoon of soil contains 120,000 fungi

Fungal uses Antibiotics Baking and brewing Decomposing Used as natural pesticides

KingdomFungi Nutritional TypeChemoheterotroph MulticellularityAll, except yeasts Cellular Arrangement Unicellular, filamentous, fleshy Food Acquisition Method Absorptive give off enzymes to break down complex nutrients Characteristic FeaturesSexual and asexual spores Embryo FormationNone Fungi

Spread by forming spores carried by wind or rain Extension of hyphae

Figure 12.2 Molds The fungal thallus consists of hyphae – strands of cells; a mass of hyphae is a mycelium.

Mucor : a microbial genus of about 3000 species. commonly found in soil, digestive systems, plant surfaces, and rotten vegetable matter Photo by Rachael Wilson

Mucor with zygotes slide Photo by Charles Philips 2015

Figure 12.3 Yeasts Unicellular fungi Fission yeasts divide symmetrically Budding yeasts divide asymmetrically

Figure 12.1 Vegetative Growth

Yeast : Saccaromyces budding Saccaromyces used in fermentation Single celled Multiply by budding

Let’s lab it up

Figure 12.4 Fungal Dimorphism Pathogenic dimorphic fungi are yeastlike at 37°C and moldlike at 25°C

Figure 12.5a Asexual Reproduction Conidia or conidiospores asexual non-motile spores

Figure 12.5b Asexual Reproduction Arthroconidia – segments of hyphae forming spore

Figure 12.5c Asexual Reproduction Blastoconidia – budding cells

Figure 12.5d Asexual Reproduction Chlamydoconidia thick walled section that may break off forming a new fungi

Figure 12.5e Asexual Reproduction Sporangiospores

Sexual Reproduction Three phases: – Plasmogamy: cytoplasm of two cells fuse and Haploid donor cell nucleus (+) penetrates cytoplasm (–) – Karyogamy: + and – nuclei fuse – Meiosis: Diploid nucleus produces haploid nuclei (sexual spores)

Figure 12.6 Sexual Spores Zygospore: Fusion of haploid cells produces one zygospore

Figure 12.7 Sexual Spores Ascospore: Spore formed in a sac (ascus).

Figure 12.8 Sexual Spores Basidiospore: Formed externally on a pedestal (basidium)

Zygomycota Conjugation fungi Coenocytic Produce sporangiospores and zygospores – Rhizopus, Mucor (opportunistic, systemic mycoses) – Mold found on fruit – 1% of fungi – usually in soil and on decaying plant matter. – they decompose soil, plant matter, and dung, they have a major role in the carbon cycle. – Can be pathogens for animals, amoebas, plants

Ascomycota Sac fungi Septate Teleomorphic fungi – Produce sexual and asexual spores Ascospores and frequently conidiospores – Aspergillus (opportunistic, systemic mycosis) – Blastomyces dermatitidis, Histoplasma capsulatum (systemic mycoses) – Microsporum, Trichophyton (cutaneous mycoses) Some Common Species – Saccharomyces cervisiae (baker's yeast) – Penicillium chrysogenum (penicillin) – Morchella esculentum (morels), typically mushrooms rare – Candid albicans (which causes thrush, diaper rash, and vaginitis)

Basidiomycota Club fungi – mushrooms, puffballs, boletes, chanterelles, earth stars, smuts, rusts Septate Produce basidiospores and sometimes conidiospores – Cryptococcus neoformans (systemic mycosis)

Cryptococcus neoformans – fungal pathogen

Anamorphs Produce asexual spores only – rRNA sequencing places most in Ascomycota; a few are Basidiomycota Examples – Penicillium – Sporothrix (subcutaneous mycosis) Rose handlers disease – infected by puncture – Stachybotrys, Coccidioides, Pneumocystis (systemic mycoses) – Candida albicans (cutaneous mycoses) Thrush – lives naturally in mouth and gut

Economic Effects of Fungi Saccharomyces cerevisiae: Bread, wine, HBV vaccine Trichoderma: Cellulase which breaks down cellulose – found in soil in symbiosis with plants Taxomyces: Taxol: drug used to treat breast and lung cancer Entomophaga: Biocontrol Paecilomyces: Kills termites

Fungal Diseases (Mycoses) Systemic mycoses: Deep within body Subcutaneous mycoses: Beneath the skin Cutaneous mycoses: Affect hair, skin, and nails Superficial mycoses: Localized, e.g., hair shafts Opportunistic mycoses: Caused by normal microbiota or environmental fungi