1 Eukaryotic Microbial Diversity Early attempts at taxonomy: all plants and animals Whitaker scheme (late 20th century) –Five kingdoms –Modified by Woese’s work on rRNA Three Domains, one of which is Eukaryotes Next two lectures on two eukaryotic kingdoms –Fungi –Protists potatoes/imatges-hotpot/Euglena.jpg

2 Eukaryotes vs. prokaryotes Eukaryotes are larger Eukaryotes have membrane- bound organelles –Nucleus, mitochondria, membrane systems –Larger size requires functional compartments –Mitochondria once bacteria? So same size!

3 Microbial eukaryotes Animals –Parasitic worms; studied by Parasitologists Fungi –Yeasts and molds, studied by Mycologists –Several types can cause human disease Protists –Unicellular eukaryotes with many different characteristics. Also studied by Parasitologists. –Some cause human disease Plants: not of particular interest other than hosts

4 Fungi Mycology: the study of fungi Fungi are mostly saprophytes, all heterotrophs –Saprophytes: decay non-living organic matter Fungi are the kings of decomposition –Heterotrophs: use pre-formed organic matter Not autotrophs, not photosynthetic Fungi grow into, through their food –Release extracellular enzymes, break down polymers into LMW compounds for transport

Heterotrophic by Absorption Fungi get carbon from organic sources Fungi get carbon from organic sources Hyphal tips release enzymes Hyphal tips release enzymes Enzymatic breakdown of substrate Enzymatic breakdown of substrate Products diffuse back into hyphae Products diffuse back into hyphae Product diffuses back into hypha and is used Nucleus hangs back and “directs”

Evolution of the fungi

7 Classification of fungi By sexual reproductive structures Fungi reproduce both asexually and sexually Deuteromycota = Fungi Imperfecti –No longer a valid classification –Contained fungi that couldn’t be coaxed into having sex –Through morphological and molecular means (e.g. DNA analysis), being distributed into the other 3 phyla of fungi.

Classification & Phylogeny motile spores zygosporangia asci basidia

9 Fungi terminology and structure Hypha (singular) hyphae (plural): thread –Hyphae may be partially separated into cells or not at all (ceonocytic). Cytoplasm is continuous throughout hypha Mycelium (plural mycelia): a mass of hyphae –Like a bacterial colony except really all one organism. Some fungi are molds, some are yeasts –Yeasts are oval, unicellular –Dimorphic: able to grow as either form. Typical of some disease-causing fungi

Hyphae Tubular Hard wall of chitin Crosswalls may form compartments (± cells) Multinucleate Grow at tips

Reproduce by spores Spores are reproductive cells –Sexual (meiotic in origin) –Asexual (mitotic in origin) Formed: –Directly on hyphae –Inside sporangia –Fruiting bodies Amanita fruiting body Pilobolus sporangia Penicillium hyphae with conidia

12 Impacts of Fungi Disease: mycosis (plural mycoses) –Most are saprobes, but some cause disease Antibiotic production –Penicillium, Cephalosporium Food industry –Soy sauce, cheeses Decomposition –Cellulose and other plant polymers, wood –stone, paintings, paint, plastic Plant pathogens –Rice, fruit, etc.

Mycorrhizae “Fungus roots” “Fungus roots” Mutualism between: Mutualism between: Fungus (nutrient & water uptake for plant) Fungus (nutrient & water uptake for plant) Plant (carbohydrate for fungus) Plant (carbohydrate for fungus) Several kinds Several kinds Zygomycota – hyphae invade root cells Zygomycota – hyphae invade root cells Ascomycota & Basidiomycota – hyphae invade root but don’t penetrate cells Ascomycota & Basidiomycota – hyphae invade root but don’t penetrate cells Extremely important ecological role of fungi! Extremely important ecological role of fungi!

Fungi and Disease Classification of fungal diseases Superficial, cutaneous, subcutaneous Superficial, cutaneous, subcutaneous Systemic and opportunistic Systemic and opportunistic Poisoning and allergies Poisoning and allergies Treatment Treatment Azole drugs, amphotericin B, others Azole drugs, amphotericin B, others

Opportunistic infections Aspergillus (aspergillosis) Aspergillus (aspergillosis) Variety of species, very common in soil, plant materials Variety of species, very common in soil, plant materials Serious infections in immunocompromised Serious infections in immunocompromised Allergies to A. fumigatus Allergies to A. fumigatus Poisoning from aflatoxin from A. flavus Poisoning from aflatoxin from A. flavus Candida (candidiasis)- normal microbiota Candida (candidiasis)- normal microbiota Cause of vaginal infections, diaper rash, thrush Cause of vaginal infections, diaper rash, thrush Capable of infecting any part of the body Capable of infecting any part of the body Dangerous in cancer patients, HIV infections, etc. Dangerous in cancer patients, HIV infections, etc.

Opportunists-2 Cryptococcus neoformans Cryptococcus neoformans Inhalation of spores Inhalation of spores Can infect many parts, but has predilection for CNS Can infect many parts, but has predilection for CNS Particularly serious in AIDS Particularly serious in AIDS Pneumocystis carinii Pneumocystis carinii Very protozoan like, but is a fungus Very protozoan like, but is a fungus Most cases associated with AIDS Most cases associated with AIDS Serious lung infections: PCP (P. carinii pneumonia) Serious lung infections: PCP (P. carinii pneumonia)