Foundations in Microbiology Sixth Edition Chapter 10 Survey of Eucaryotic Microbes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 Survey of Eucaryotic Microbes Fungi Algae Protozoa Parasitic worms

3 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

4 Microscopic Fungi 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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7 Fungal Nutrition 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 20 o -40 o C Extremely widespread distribution in many habitats

8 Fungal Organization 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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10 Fungal Reproduction Primarily through spores formed on reproductive hyphae Asexual reproduction – spores are formed through budding or mitosis; conidia or sporangiospores

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12 Fungal Reproduction Sexual reproduction – spores are formed following fusion of male and female strains and formation of sexual structure Sexual spores and spore-forming structures are one basis for classification.

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16 Roles of Fungi 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

17 Kingdom Protista Algae Protozoa

18 Algae Photosynthetic organisms Kelps, seaweeds, euglenids, green algae, diatoms, dinoflagellates, brown algae, and red seaweeds Microscopic forms are unicellular, colonial, filamentous. Macroscopic forms are colonial and multicellular. Contain chloroplasts with chlorophyll and other pigments Cell wall May or may not have flagella

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20 Protozoa 65,000 species Vary in shape, lack a cell wall Most are unicellular; colonies are rare Most are harmless, free-living in a moist habitat Some are animal parasites and can be spread by insect vectors. All are heterotrophic. Feed by engulfing other microbes and organic matter

21 Protozoa Most have locomotor structures – flagella, cilia, or pseudopods. Exist as trophozoite - motile feeding stage Many can enter into a dormant resting stage when conditions are unfavorable for growth and feeding – cyst. All reproduce asexually, mitosis or multiple fission; many also reproduce sexually – conjugation.

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23 Important Protozoan Pathogens Pathogenic flagellates –Trypanosomes – Trypanosoma T. brucei – African sleeping sickness T. cruzi – Chaga’s disease; South America Infective amebas –Entameba histolytica – amebic dysentery; worldwide

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26 Parasitic Helminths Multicellular animals, organs for reproduction, digestion, movement, protection Parasitize host tissues Have mouthparts for attachment to or digestion of host tissues Most have well-developed sex organs that produce eggs and sperm. Fertilized eggs go through larval period in or out of host body.

27 Major Groups of Parasitic Helminths 1.Flatworms – flat, no definite body cavity; digestive tract a blind pouch; simple excretory and nervous systems cestodes (tapeworms) Trematodes or flukes, are flattened, nonsegmented worms with sucking mouthparts. 2.Roundworms (nematodes)- round, a complete digestive tract, a protective surface cuticle, spines and hooks on mouth; excretory and nervous systems poorly developed

28 Helminths 50 species parasitize humans. Acquired though ingestion of larvae or eggs in food; from soil or water; some are carried by insect vectors Afflict billions of humans

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31 Helminth Classification and Identification Classify according to shape, size, organ development, presence of hooks, suckers, or other special structures, mode of reproduction, hosts, and appearance of eggs and larvae Identify by microscopic detection of adult worm, larvae, or eggs

32 Distribution and Importance of Parasitic Worms Approximately 50 species parasitize humans. Distributed worldwide; some restricted to certain geographic regions with higher incidence in tropics