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Survey of Eukaryotic Microbes

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1 Survey of Eukaryotic Microbes
Fungi Algae Lichens Chapters 5 & 22 Talaro Foundations in Microbiology

2 Kingdom Fungi 100,000 species divided into 2 groups macroscopic fungi
microscopic fungi Heterotrophic none are autotrophic on their own Majority are harmless saprobes living off dead and decaying plants & animals Some are parasites, but none are obligate Mycoses Optimal growth temperature generally mesophilic 20o - 40oC but many can grow at 4oC Extremely widespread distribution in many habitats Reproduce through spores formed on special reproductive hyphae Asexual reproduction Spores are formed through budding or conidia formation Sexual reproduction Spores are formed following fusion of male & female strains & formation of sexual structure Sexual spores are one basis for classification Mycology – the study of fungi

3 Body of Mold Septum crosswall Aseptate or coenocytic Conidium
asexual spore hypha Mycelium A mass of hyphae Body of Mold

4 Asexual spores on aerial mycelia

5 Four Main Divisions Zygomycetes Ascomycetes Basidiomycetes
Plasmogamy - haploid nucleus of donor cell (+) penetrates cytoplasm of recipient cell (__) Karyogamy - (+) and (__) nuclei fuse to form a diploid zygote nucleus Meiosis - diploid nuclei gives rise to haploid nuclei Zygomycetes Ascomycetes Basidiomycetes Deuteromycetes No sexual spores Called by many the Fungi Imperfecti

6 Zygomycetes

7 Ascomycetes

8 Unicellular Fungi - Yeast
Two general classes - budding and fission yeast Cell division distinguishes two classes Budding yeast do not divide evenly Fission yeast divide evenly Saccharomyces cerevisiae Ascomycetes with an infrequent sexual stage Schizosaccharomyces pombe

9 Basidomycetes

10 Fungi as Infectious Agents
Molds & yeasts are widely distributed in air, dust, fomites & normal flora Humans are relatively resistant Fungi are relatively nonpathogenic except to immunosupressed patients Only 300 have been linked to disease in animals, of the 100,000 fungal species Human mycoses are caused by true pathogens and opportunistic pathogens

11 Dimorphic Fungi

12 Fungal Infection Systemic Mycoses
Deep infection, usually multiple organs affected, not transferable from organism to organism Subcutaneous Mycoses Infection beneath surface of skin, requires implantation of hyphae or spores via puncture wound Cutaneous Mycoses Caused by dermatophytes (infect epidermis, hair or nails), secrete keritinase, human to human transmission Superficial Mycoses Localized along hair shafts and superficial (surface) epithelial cells

13 Antifungal Compounds Antifungals are placed into 3 categories based on their mode of action Azoles Inhibit the synthesis of ergosterol, the main fungal sterol in the plasma membrane e.g., Miconazole Polyenes Interact with fungal membrane sterols and creates pores in the plasma membrane e.g., Amphotericin B 5-fluorocytosine Cytosine analog Inhibits nucleic acid synthesis Fungal infections of the blood, lungs, heart & CNS and urinary tract

14 Systemic Mycoses caused by True Pathogens
Histoplasma capsulatum Coccidioides immitis Blastomyces dermatitidis Paracoccidioidomycosis brasiliensis

15 Histoplasma capsulatum
Histoplasmosis Typically dimorphic Distributed worldwide, most prevalent in eastern & central regions of US Grows in moist soil high in nitrogen content Inhaled conidia produce primary pulmonary infection that may progress to systemic involvement of a variety of organs & chronic lung disease Amphotericin B Polyene Ketoconazole Azole

16 Histoplasma capsulatum
Yeast like colony 25 ºC Hyphal growth Histoplasmosis!!

17 Subcutaneous Mycoses Mycetoma or Eumycetoma Madurella mycetomatis
Agricultural workers Ketoconale Azole Itraconazole Amputation

18 Cutaneous Mycoses Infections strictly confined to keratinized epidermis (skin, hair, nails) are called dermatophytoses - ringworm & tinea 39 species in the genera Trichophyton, Microsporum, Epidermophyton Communicable among humans, animals, & soil Infection facilitated by moist, chafed skin

19 Ringworm of scalp (tinea capitis) affects scalp & hair-bearing regions of head; hair may be lost
Ringworm of body (tinea corporis) occurs as inflamed, red ring lesions anywhere on smooth skin Ringworm of groin (tinea cruris) “jock itch” affects groin & scrotal regions Ringworm or foot & hand (tinea pedis & tinea manuum) is spread by exposure to public surfaces; occurs between digits & on soles Ringworm of nails (tinea unguium) is a persistent colonization of the nails of the hands & feet that distorts the nail bed

20 Ringworm Treatment Ointments containing Tolnaftate Miconazole Lamisil
Griseofulvin Inhibits fungal microtubules

21 Tinia Capitis Tinea Corporis

22 Ringworm of the extremities
Trichophyton Ringworm of the extremities Tinia unguium

23 Superficial Mycoses Tinea versicolor causes mild scaling, mottling of skin White piedra is whitish or colored masses on the long hairs of the body Black piedra causes dark, hard concretions on scalp hairs

24 Opportunistic Mycoses
Opportunistic fungal pathogen Host’s defense must be impaired. Fungus has a weak or nonexistent virulence in a host with a normal functioning immune system.

25 Candida albicans Normal flora of oral cavity, genitalia, large intestine or skin of humans Account for 80% of nosocomial fungal infections Account for 30% of deaths from nosocomial infections Thrush Occurs as a thick, white, adherent growth on the mucous membranes of mouth & throat Vulvovaginal yeast infection Painful inflammatory condition of the female genital region that causes ulceration & whitish discharge Cutaneous candidiasis Occurs in chronically moist areas of skin and burn patients

26 Candida albicans Candida Cryptococcus

27 Cryptococcus neoformans
A widespread encapsulated yeast that inhabits soils around pigeon roosts causes Cryptococcosis Common infection of AIDS, cancer or diabetes patients Infection of lungs leads to cough, fever, & lung nodules Dissemination to meninges & brain can cause severe neurological disturbance & death

28 Cryptococcus neoformans

29 Pneumocystis carinii A small, unicellular fungus that causes pneumonia (PCP) The most prominent opportunistic infection in AIDS patients This pneumonia forms secretions in the lungs that block breathing & can be rapidly fatal if not controlled with medication Pentamidine Mode of action is unclear Investigations indicate that the drug inhibits the synthesis of DNA, RNA, phospholipids and proteins Cotrimoxazole Folate inhibitor Azole

30 Pneumocystis carinii Fungal cysts in lung tissue

31 Aspergillus Very common airborne soil fungus 600 species
8 involved in human disease Inhalation of spores causes fungus balls in lungs and invasive disease in the eyes, heart, & brain Amphotericin B Polyene Nystatin

32 Zygomycosis Zygomycetes are extremely abundant saprobic fungi found in soil, water, organic debris, & food Genera most often involved are Rhizopus, Absidia, & Mucor Usually harmless air contaminants invade the membranes of the nose, eyes, heart, & brain of patients with either diabetes or malnutrition with severe consequences.

33 Alga / Algae Photosynthetic protists Photoautotrophic
Some biologists refer to them as algae Photoautotrophic Contain chloroplasts with chlorophyll & other pigments Produce large proportion of atmospheric O2 Provide basis of food web in most aquatic habitats Not classified as plants Lack many plant structures Cuticle, vascular tissues, cell wall primarily composed of cellulose Cell wall Contains cellulose, unique polysaccharides & variety of glycoproteins May or may not have flagella Microscopic forms are unicellular, colonial, filamentous Macroscopic forms are colonial & multicellular Most are free-living in fresh and marine water Some inhabit soil or trees Water required for all aspects of life Cellular support, reproduction, and nutrient acquisition

34 Algae Classified according to types of pigments & components of the cell wall Must use pigment that absorbs light l that has not been filtered out Littoral zone is defined as the area between the high water and low water marks



37 Dinoflagellates Unicellular algae - plankton
Interlocking cellulose plates embedded in plasma membrane, structural integrity Two flagella, propel by spinning through water Photosynthetic, uses conventional chlorophyll, also accessory pigments Some exist in as endosymbionts Jellyfish, corals & mollusks Provide food to host organism through photosynthesis, host organism protects dinoflagellate from environment

38 Some produce toxins and cause of PARALYTIC SHELLFISH
POISONING Paralytic shellfish poisoning side affect of RED TIDE Toxins produced by dinoflagellates accumulate in shellfish Toxin harmless to shellfish, very harmful (sometimes fatal) to other life Eating poorly prepared contaminated shellfish (oysters on the half shell) causes paralytic disease

39 Diatoms Phytoplankton Unicellular or chains Silica cell wall
Two symmetrical sides Marine, freshwater & soil Two halves Carbon cycle Silicon cycle Progressively smaller

40 Brown Algae Kelp Brown algae include the largest protists
Macroscopic - can reach lengths of 50 m (Macrocystis pyrifera) Rapid growth rate - 20 cm/day Many commercial uses Thickener for cooking, rubber tires, hand lotions

41 Red Algae / Rhododphyta
Occupy greater depths than other algae Red pigment allows algae to absorb blue light Source of agar Bacteriological growth medium Source of carrageenan Thickening agent Evaporated milk, ice cream

42 Green Algae Many plant like characteristics
Cellulose cell wall, chlorophyll a and b, starch for energy storage Hypothesized ancestors of terrestrial plants Either unicellular or multicellular Most are microscopic

43 Lichens Combination of fungus and photosynthetic organisms
photobiont or phycobiont Green algae, cyanobacterium Yellow green algae or brown algae There are some examples of a lichens containing both green algae and cyanobacteria Placed in kingdom fungi, classified based on fungal partner Ascomycetes & Basidiomycetes Symbiotic relationship benefits both partners Harshes environments Deserts to Antartica Primary colonists – require water Resistant to dessication Obligatory for the fungus Relationship is typically not obligatory for the photobiont Y


45 Soredium Soredium spread by wind Algal cells are not endosymbionts
There is one example of the cyanobacteria as true endosymbionts

46 Lichens are not plants and do not have roots
Grown on the surface of rocks, soil, sand, walls, roofs and monuments Lichens also grow as epiphytes on other plants Trunks and branches of trees Secrete organic acids which breaks down substratum Part of nutrient cycling Very slow growing organisms Important food source for reindeer Bioindicator species


48 Fructicose

49 Reproduce by fragmentation
A few algal cells surrounded by fungal hyphae

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