1Eukaryotic 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

http://www.xtec.cat/~jfarre13/hot-potatoes/imatges-hotpot/Euglena.jpgwww.kc-mtm.com

2Eukaryotes 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!

http://www.earthlife.net/images/eury-cell.gif

3Microbial 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

4Fungi

• 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 AbsorptionHeterotrophic by Absorption

Fungi get carbon from organic sourcesFungi get carbon from organic sources Hyphal tips release enzymesHyphal tips release enzymes Enzymatic breakdown of substrateEnzymatic breakdown of substrate Products diffuse back into hyphaeProducts diffuse back into hyphae

Product diffuses backinto hypha and is used

Nucleus hangs backand “directs”

Evolution of the fungiEvolution of the fungi

7Classification 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

ascibasidia

9Fungi 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

12Impacts 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.

MycorrhizaeMycorrhizae ““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 kindsSeveral kinds Zygomycota – hyphae invade root cellsZygomycota – hyphae invade root cells Ascomycota & Basidiomycota – hyphae invade Ascomycota & Basidiomycota – hyphae invade

root but don’t penetrate cellsroot but don’t penetrate cells

ExtremelyExtremely important ecological role of fungi! important ecological role of fungi!

Fungi and DiseaseFungi and Disease

Classification of fungal diseasesClassification of fungal diseasesSuperficial, cutaneous, subcutaneousSuperficial, cutaneous, subcutaneousSystemic and opportunisticSystemic and opportunisticPoisoning and allergiesPoisoning and allergies

TreatmentTreatmentAzole drugs, amphotericin B, othersAzole drugs, amphotericin B, others

Opportunistic infectionsOpportunistic infections AspergillusAspergillus (aspergillosis) (aspergillosis)

Variety of species, very common in soil, plant Variety of species, very common in soil, plant materialsmaterials

Serious infections in immunocompromisedSerious infections in immunocompromisedAllergies to Allergies to A. fumigatusA. fumigatusPoisoning from aflatoxin from Poisoning from aflatoxin from A. flavusA. flavus

CandidaCandida (candidiasis)- normal microbiota (candidiasis)- normal microbiotaCause of vaginal infections, diaper rash, thrushCause of vaginal infections, diaper rash, thrushCapable of infecting any part of the bodyCapable of infecting any part of the bodyDangerous in cancer patients, HIV infections, etc.Dangerous in cancer patients, HIV infections, etc.

Opportunists-2Opportunists-2

Cryptococcus neoformansCryptococcus neoformans Inhalation of sporesInhalation of sporesCan infect many parts, but has predilection for Can infect many parts, but has predilection for

CNSCNSParticularly serious in AIDSParticularly serious in AIDS

Pneumocystis cariniiPneumocystis cariniiVery protozoan like, but is a fungusVery protozoan like, but is a fungusMost cases associated with AIDSMost cases associated with AIDSSerious lung infections: PCP (Serious lung infections: PCP (P. cariniiP. carinii pneumonia) pneumonia)