Kingdom Fungi

prominent members of ecosystems

useful as model systems and industry

some are major human pathogens

two groups

protists

fungi

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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

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Exist in two morphologies:

Yeast – round ovoid shape, asexual reproduction

Hyphae – long filamentous fungi or molds

Some exist in either form – dimorphic – characteristic of some pathogenic molds

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Figure 5.15

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Figure 5.16c

All are heterotrophic

Majority are harmless saprobes living off dead plants and animals

Some are parasites, living on the tissues of other organisms, but none are obligate Mycoses – fungal infections

Growth temperature 20o-40oC

Extremely widespread distribution in many habitats

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Most grow in loose associations or colonies

Yeast – soft, uniform texture and appearance

Filamentous fungi – mass of hyphae called mycelium; cottony, hairy, or velvety texture

Hyphae may be divided by cross walls – septate

Vegetative hyphae – digest and absorb nutrients

Reproductive hyphae – produce spores for reproduction

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Isolation on specific media

Macroscopic and microscopic observation of: Asexual spore-forming structures and spores

Hyphal type

Colony texture and pigmentation

Physiological characteristics

Genetic makeup

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Primarily through spores formed on reproductive hyphae

Asexual reproduction – spores are formed through budding or mitosis; conidia or sporangiospores

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Figure 5.19

Sexual reproduction – spores are formed following fusion of two different strains and formation of sexual structure

Zygospores, ascospores, and basidiospores

Sexual spores and spore-forming structures are one basis for classification

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Kingdom Eumycota is subdivided into several phyla based upon the type of sexual reproduction:

1. Zygomycota – zygospores; sporangiospores and some conidia

2. Ascomycota – ascospores; conidia

3. Basidiomycota – basidiospores; conidia

4. Chytridomycota – flagellated spores

5. Fungi that produce only Asexual Spores (Imperfect)

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Figure 5.20 Formation of zygospores

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Figure 5.21 Production of ascospores

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Figure 5.22 Formation of basidiospores in a mushroom

Adverse impact Mycoses, allergies, toxin production

Destruction of crops and food storages

Beneficial impact Decomposers of dead plants and animals

Sources of antibiotics, alcohol, organic acids, vitamins

Used in making foods and in genetic studies

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