Survey of Eukaryotic Microbes

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. 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 • 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 • Paracoccidioidomycosisbrasiliensis

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 36 ºC Yeast like colony 25 ºC Hyphal growth Histoplasmosis!!

17. Subcutaneous Mycoses • Mycetoma or Eumycetoma • Madurella mycetomatis • Agricultural workers • Ketoconale • Azole • Itraconazole • Azole • 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 • Azole • Miconazole • Azole • Lamisil • Azole • Griseofulvin • Inhibits fungal microtubules

21. Tinia Capitis Tinea Corporis

22. 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 cariniiFungal 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 • Polyene

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 • 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

44. community.iexplore.com/photogallery/ www.anta.canterbury.ac.nz/

45. Soredium spread by wind Soredium 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