Survey of eucaryotic microbes

• Fungi

• Algae

• Protozoa

• Parasitic helminths (worms)

Kingdom Fungi

• 100,000 species divided into 2 groups:– macroscopic fungi (mushrooms, puffballs, gill

fungi)– microscopic fungi (molds, yeasts)

• majority are unicellular or colonial, a few have cellular specialization

Roles of fungi

• decomposers of dead plants and animals

• sources of antibiotics

• used in making foods & in genetic studies

• adverse impact – food spoilage, mycoses, toxin production

microscopic fungi

• exist in 2 morphologies1. yeast – unicellular, round ovoid shape,

asexual reproduction (budding or transverse division) – also can form pseudohyphae

2. Filamentous (“mold”) - hyphae – long filamentous fungi or molds; forms tangled mass=mycelium

• some exist in either form – dimorphic – characteristic of pathogens

yeasts• Reproduces by budding

or transverse division (asexual)

• Can form pseudohyphae (chains)

• Some can also form spores (sexual repro)

• Example: Saccharomyces cerevisae (Brewer’s or baker’s yeast)

Molds (hyphae)

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Figure 5.15

Fungal nutrition• all are _________________• majority are harmless __________living off dead

plants & animals (saprophytes)– secrete hydrolytic enzymes, digest externally

• some are parasites, living on the tissues of other organisms, but none are obligate; __________= fungal infections

• growth temperature 20o-40oC• extremely widespread distribution, many habitats

Fungal Reproduction• primarily through __________formed on special

reproductive __________– asexual reproduction – spores are formed through

budding (yeasts) or in __________or _______________________ (molds)

– sexual reproduction – spores are formed following fusion of male & female strains & formation of sexual structure

• sexual spores are one basis for __________

I. Asexual reproduction

• Transverse fission

• Budding

• Spores (most common)– Sporaniogpores – spores enclosed in head

(sporangium) – sits atop stalk (___________________)

– Conidia – free spores

Molds - Reproduction

Sporangiospores

• Stalk =

• Sac =

• Spores =

I. Asexual Reproduction

Conidia

• All form on top of stalk (conidiophore)• Arthrospores – septate hypha – fragments break off

• Chlamydospores – spherical, thickened hyphal cell Blastospore = bud

• Phialospore – buds from vase shaped phialide• Micro/macro conidium – small and large

versions of conidia, 1 and 2+celled, respectively.• Porospore – conidium that grows from pore

I. Asexual Reproduction

You do NOT have to memorize these types of conidia!

ConidiaI. Asexual Reproduction

Spore types and representative genera

• Sporangiospores – Absidia, Mucor

• Arthrospores – Coccidiodes

• Chlamydospores/blastospores – Candida albicans

• Phialospores – Aspergillus, Penicillium

• Micro/microconidia – Microsporum, Fusarium

• Porospores - Alternaria

I. Asexual Reproduction

You do NOT have to memorize these types of conidia!

II. Sexual reproduction

• Involves fertilization – union of compatible nuclei

• Some can self-fertilize

• Can yield spores:

– Zygospore

– Ascospore

– Basidiospore

4 main divisions of molds based on sexual spore type

1. Zygomycota

2. Ascomycota

3. Basidiomycota

4. Deuteromycota – no sexual spores?

II. Sexual Reproduction

Zygomycota Ascomycota Basidiomycota

Detueromycota

Sexual spores

zygo- asco- basidio- None or not described

Asexual spores

Sporangio-

(some conidia)

Types of conidia Conidia Var. conidia

Hyphae Nonseptate or complete septa

Porous septate Incompletely septate

septate

Lifestyle Mostly saprobes some parasites

Many important species and pathogens

Fleshy fruiting bodies; some plant parasites, 1 pathogen

Some dimorphic; saprobes and some parasites

examples Rhizopus, Mucor Agents of dermatophytosis, Histoplasma, Penicillium, Saccharomyces, Pneumocystis carinii

Cryptococcus neoformans; mushrooms, puffballs, rusts, smuts

Coccidioides immitis, Candida albicans, Cladosporium, Strachybotrys

Fungal pathogenesis (mycosis)

• Most fungi are not true pathogens (they don’t attack healthy people)

• Most are ______________– invade those with compromised immune systems (AIDS, cancer, diabetes)

• Degree of mycosis (disease) varies by mode of infection and organs involved

• Fungi also cause ______________– , and produce ______________–

mycosis

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Considered the most pathogenic fungus

Important fungal diseasesMicroorganism Associated Disease(s)

Trichophyton spp. Epidermophyton spp. Microsporum spp.

Tinea capitis (ringworm); Tinea cruris (jock itch); Tinea pedis (athlete's foot);Tinea unguum (finger and toenails); Tinea corporum (body); Tinea barbae (beard)

Candida albicans vaginal yeast infections, oral thrush, nail fungus

CoccidiodesCoccidiomycosis – lung/systemic – VERY deadly

Blastomyces dermatitidis

blastomycosis (skin, lungs, organs)

Aspergillus spp. aspergillosis

Athlete’s foot

ringworm

Nail fungus

mycosis

Blastomycosis

CoccidiomycosisCoccidiomycosis

Oral thrush – C. albicans

Case study: mucormycosis

• Mucor sp. – common mold of soil, bread, fruit etc.

• Opportunistic infection

• Mark Tatum – steroids suppressed his immune system

• Inhaled spores infection in sinus

• Had to have sinuses removed including nose, eyes and face

mycosis

mycosis

Benefits of fungi

• Decomposers of organic matter (recycle nutrients)

• Symbiosis with plant roots

• Produce antibiotics, organic acids, vitamins

• Fermentation (alcohol)

• Foods – bread, cheese; also eaten as foods

Identifying Fungi

• Media – cornmeal, blood, Sabouraud’s agar

• ID by asexual stages (sexual not common in lab cultures)

• Also physical characteristics: hyphae, colony morphology, color, other characteristics

• Genetic tests

Kingdom Protista

• Algae – photosynthetic, plant-like

• Protozoa – nonphotosynthetic, animal-like

Algae• photosynthetic organisms• contain chloroplasts with chlorophyll & other

pigments; cell wall; may or may not have flagella • kelps, seaweeds, euglenids, green algae, diatoms,

dinoflagellates, brown algae, & red seaweeds• microscopic forms are unicellular, colonial,

filamentous• macroscopic forms are colonial and multicellular• most are free-living in fresh and marine water

(you have seen examples off all of these in lab)

Fig. 5.26Algae

Algae• classified according to types of pigments & cell

wall

• provide basis of food web in most aquatic habitats (plankton)

• produce large proportion of atmospheric O2

• used for cosmetics, food & medical products

• _______________ cause red tides & produce toxins – paralytic shellfish poisoning

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Dinoflagellates• Paralytic shellfish poisoning –

accumulation of toxins in clams and other shellfish

• Ciguatera – accumulation in fish - no antidote for toxin. Can be self-limiting.

• _______________ _______________ (pfiesteriosis)– parasite of fish and humans; algal blooms from agricultural runoff; also has potent toxins