Unit 4. Chapter 5. ch 5.3. Eukaryotes. section 3.Fungi.final.Sversion.pptx

Eukaryotes of microbiology Section 1. Fungi Chapter 5.3, Figures and some discussion from chapters 5.5, 17, 21, 22 Introduction Fungi • Mycology- study of fungi • Fungi • unicellular, eukaryotic plant-like organisms • 1.5 million species • Different from plants: • lack chlorophyll, and thus cann...

Eukaryotes of microbiology Section 1. Fungi Chapter 5.3, Figures and some discussion from chapters 5.5, 17, 21, 22 Introduction Fungi • Mycology- study of fungi • Fungi • unicellular, eukaryotic plant-like organisms • 1.5 million species • Different from plants: • lack chlorophyll, and thus cannot undergo photosynthesis • Heterotrophic while plants are autotrophic • Cell wall made out of chitin(acetylglucosamine units) as opposed to cellulose in plants • Not truly multicellular Fungi versus Eubacteria Feature Cell type Cell membranes Fungi Eukaryotic Sterols present Cell wall Glucans, mannans, chitin (no peptidoglycan) Produce a wide variety of sexual and asexual reproduction Limited to heterotrophic, anaerobic, facultative anaerobic spores Metabolism Sensitivity to antibiotics Often sensitive to polyenes, imidazoles, and griseofulvin Eubacteria Prokaryotic Sterols absent, except Mycoplasma Peptidoglycan Endospores/ not for reproduction Photoautotrophic, aerobic, facultative anaerobic, heterotrophic, chemoautotrophic Often sensitive to penicillin, tetracyclines, aminoglycosides 2 forms • Exist in two forms • Fungi can grow as multicellular mold or as unicellular yeast Mold • Aerobic • Hyphae-microscopic, long, branching, threadlike filaments • Grow into visible, filamentous mass to form mycelium. • Reproduction • Molds reproduce by forming spores. • Mold spores are frequently airborne and are a common source of contamination of laboratory cultures as well as causing allergic reactions in sensitize individuals. A Wall of Mold © Scott Threlkeld, The Times-Picayune/Landov Mold: hyphae • Growth of hyphae • Elongate at tips • Each part can grow • Fragment breaks off/ elongate to form new hyphae • Types of hyphae • Septate • hyphae containing cross walls called septa, which divide them into distinct, uninucleate cell-like units • Pores in septa allow for some continuous cytoplasm • Nonseptate (coenocytic) • Hyphae do not contain septa, separation • Appear as long, continuous cells with many nuclei • Cytoplasmic streaming( continuous cytoplasm)/ not clearly defined divisions Figure 5.25 • Multicellular fungi (molds) form hyphae, which may be septate or nonseptate. Unicellular fungi (yeasts) cells form pseudohyphae from individual yeast cells. Figure 03B: Hypha Structure Yeast • Facultative anaerobe • No flagella • Larger than bacteria • Unicellular, non-filamentous, typically spherical, oval • Single nucleus • Reproduce sexually and asexually • Sexually: • Asexually: 1) budding: parent cell protuberance on outer surface: blastospore. As bud elongates, parent cell’s nucleus divides One goes into bud Cell wall material laid down between bud and parent cell- bud breaks away E: Saccharomyces the resulting cells may sometimes stick together as a short chain or pseudohypha 2) transverse division: divide evenly to produce to new cells Parent cell elongate, nucleus divides 2 daughter cells produced. Ex: Schizosaccharomyces • • • • • • • • • Figure 07: Yeast buddin Dimorphism • Certain fungi can take either form depending on the conditions • By location: • Within animal tissue: yeast stage Outside animal: hyphae • Within plant tissue: hyphae Outside plant: yeast • By temperature: • 25C : hyphae • 37C: yeast • Example: Histoplasma capsulatum- Summer flu Figure 5.26 • Histoplasma capsulatum is a dimorphic fungus that grows in soil exposed to bird feces or bat feces (guano) (top left). It can change forms to survive at different temperatures. In the outdoors, it typically grows as a mycelium (as shown in the micrograph, bottom left), but when the spores are inhaled (right), it responds to the high internal temperature of the body (37 °C [98.6 °F]) by turning into a yeast that can multiply in the lungs, causing the chronic lung disease histoplasmosis. (credit: modification of work by Centers for Disease Control and Prevention) Nutrition • Chemoheterotrophs/ non-photosynthetic • Most aerobes • Absorb rather than ingest nutrients • Obtain carbon in three ways • 1) saprophyte- organism that obtains its nutrients from dead remains • 2) parasite- organism that obtains its nutrients from living host tissue • 3) Symbiote- living together of 2 different organisms/ populations • Mutualism- Mycorrhizae( fungi-plants) contribute essential minerals and water to promote plant growth • lichen( fungus+ cyanobacteria/algae) Growth • Of hyphae: • Lengthening and branching of the hyphae at tips • Of Yeast: • Several rounds of mitosis Fungal growth is influenced by many factors • Oxygen- most aerobic except for facultative yeasts • Temperature- most grow optimally at 23oC, except for pathogenic, which grow optimally at 37oC. • Dimorphic: hyphae at 23oC, yeast at 37oC • pH- Many thrive in mildly acidic environments( pH 5-6) • Sugar- high concentrations conducive to growth Reproduction • Asexual • Formed by hyphae of one organism • When spores germinate, become organisms genetically identical to the parent. • Sexual • Result from the fusion of nuclei from two opposing mating strains of same species • Less frequency produced than asexual A Typical Fungal Life Cycle of a Mold Taxonomy Taxonomy • Chytridiomycota, Glomeromycota, Zygomycota, Ascomycota, and Basiomycota • Determined by structure, nutrition, and mostly by reproduction • Higher septated, lower not • Zygomycota, Chytridiomycota, Glomeromycota- lower (not septated) • Ascomycota and Basidiomycota- higher(septated) • Also, Urediniomycetes and Ustilagomycetes include the plant rusts and smuts, respectively. These form reddish or dark masses, respectively, on plants as rusts (red) or smuts (dark). A Phylogeny for the Kingdom Fungi. Glomeromycota • Obligate symbionts • Group of endomycorrhizae that exist in roots of more than 80% world’s land plants Chytridiomycota( chytrids) • Oldest known fungi are related to certain members of the Chytridiomycota • Ecologically important • Simplest of true fungi • Contains 1 class- chytrids • Predominantly aquatic • Flagellated reproductive cells • Thought to be derived from protozoan ancestor Zygomycota • Terrestrial, saprophytic molds with nonseptate hyphae and haploid nuclei • Important for food science and as crop pathogens • Ex: Rhizopus (black bread mold), Mucor • Structure • Nonseptate hyphae • Nutritional • Saprophytic/ parasitic • plants, insects • Deep into bread, attains nutrients Figure 5.28 • These images show asexually produced spores. (a) This brightfield micrograph shows the release of spores from a sporangium at the end of a hypha called a sporangiophore. The organism is a Mucor sp. fungus, a mold often found indoors. (b) Sporangia grow at the ends of stalks, which appear as the white fuzz seen on this bread mold, Rhizopus stolonifer. The tips of bread mold are the dark, spore-containing sporangia. (credit a: modification of work by Centers for Disease Control and Prevention; credit b right: modification of work by “Andrew”/Flickr) Zygomycota • Reproduction • Both but produces asexually most of the time • Asexual sporessporangiospores- formed on inside of specialized fruiting structure • Dark sporangiospores give characteristic black color name Figure 06A: Sporangia of bread mold Zygomycota • Sexual spores- zygospores- diploid zygote created by nuclear fusion opposing +/- haploid cells • Both asexual and sexual spores dispersed by wind currents Figure 12: Sexual Reproduction in the Zygomycota Ascomycota • Sac fungi • Account for 75% of all fungi Penicillium roquefortii • include fungi that are used as food (edible mushrooms, morels, and truffles), others that are common causes of food spoilage (bread molds and plant pathogens), and still others that are human pathogens • Ex: Aspergillus(Sake), Penicillium( Lipitor), Saccharomyces cerevisiae, Candida albicans, Neurospora crassa( genetics research ) • Structure • Molds with septate hyphae/ some yeasts • Reproduction • Both asexual and sexual Ascomycota Fig 5.29a Yeast cells ( Candida albicans) Morel mushroom Moldy orange Asexual: Conidia non-motile asexual spores, formed on outside of specialized hyphae called conidiophores Conidia are distinguished from sporangiospores in that conidia are not enclosed in a structure a b c Sexual: occasionally, when +/- meet Ascospores floating spores produced in sack-like structure called ascus: 8 haploid ascospores form © Biodisc/Visuals Unlimited Ascocarp on apple leaf Figure 5.30 • These ascospores, lined up within an ascus, are produced sexually. (credit: Peter G. Werner) Ascomycota • Some form symbioses with plants (mycorrhizae) leaves and stems(endophytes) • Fungal partner in • lichen( ascomycete fungus+ cyanobacteria/algae) • Discussed in chapter 5.5 • can potentially be found on almost any surface (especially rocks) or as epiphytes (meaning that they grow on other plants). Lichens Lichen Growing on the Surface of a Rock SEM of lichen Figure 5.39 • Examples of the three types of lichens are shown here. (a) This is a crustose lichen found mostly on marine rocks, Caloplaca marina. (b) This is a foliose lichen, Flavoparmelia caperata. (c) This is a fruticose lichen, Letharia vulpina, which is sufficiently poisonous that it was once used to make arrowheads. (credit b, c: modification of work by Jason Hollinger) Ascomycota: Diseases Diseases: nervous system • Ergot • Common in Europe during middle ages • Used to induce Abortion • St. Anthony’s fire- killed thousands of people • Witchcraft hunts result of outbreak ergotism in Massachusetts • Due to Ergometrine toxin • Produced by Claviceps purpurea, ascomycete grain pathogen • causes gangrene limbs • Numbness, epileptic type seizures, paralysis of nerve endings • LSD is derivative of alkaloid in ergot • Commercial derivatives used to induce labor Diseases: lower respiratory tract • Coccidioidomycosis• Valley desert fever • Transmitted by dust particles with fungal spores • Caused by Coccidioides immitis and C. posadasii • Produces infectious arthrospores • Dry, hacking cough, chest pains, high fever • Treatment: Amphotericin B Figure 22.23 (a) This patient has extensive facial lesions due to a disseminated Coccidioides infection. (b) This fluorescent micrograph depicts a spherule of C. immitis containing endospores. (credit a, b: modification of work by Centers for Disease Control and Prevention) The Life Cycle of Coccidioides immitis Diseases: lower respiratory tract • Histoplasmosis• “Summer flu” • Caused by Histoplasma capsulatum ( dimorphic) • Inhalation of spores present in soil, chicken coops, bat caves • Opportunistic: Affects immunocompromised, Influenza-like symptoms • Treatment: Amphotericin B or ketoconazole Histoplasma capsulatum H. capsulatum Courtesy of Dr. Libero Ajello/CDC Diseases: skin • Mycoses- fungal diseases • Dermatophysis- fungal disease of hair, skin, nails • Bartenders prone as hands always wet • Also named tinea infections, as previously believed to be caused by worms • Athlete’s foot( tinea pedis), head ringworm(tinea capitis), body ringworm( tinea corporis), groin ringworm “jock itch” (tinea cruris), nail ringworm ( tinea unguium) • Dermatophytes- Fungi that infect only epidermis, hair, nails • Secrete keratinase- degrades keratin(protein of skin, hair, nails) • Ringworm • Commonly accompanied by blister-like lesions, which leave a scaly ring as they dry • Mainly Trichophyton (nail) and Microsporum (scalp, skin) • Transmitted by pets and fomites Figure MM02: Trichophyton Figure MM03: Microsporum Figure 21.29 • Tineas are superficial cutaneous mycoses and are common. • Tinea barbae (barber’s itch) occurs on the lower face. • Tinea pedis (athlete’s foot) occurs on the feet, causing itching, burning, and dry, cracked skin between the toes. • A close-up view of tinea corporis (ringworm) caused by Trichophyton mentagrophytes. (credit a, c: modification of work by Centers for Disease Control and Prevention; credit b: modification of work by Al Hasan M, Fitzgerald SM, Saoudian M, Krishnaswamy G) Ringworm Courtesy of Dr. Libero Ajello/CDC Figure 5.34 • This micrograph shows hyphae (macroconidium) and microconidia of Trichophyton rubrum, a dermatophyte responsible for fungal infections of the skin. (credit: modification of work by Centers for Disease Control and Prevention) Diseases: skin • Candidiasis- caused by Candida albicans • Vulvovaginitis “ yeast infection” • Considered STD • Treatment: • Nystatin(Mycostatin)- A polyene, works by binding to ergosterol, leadin to leakage of cell’s contents • Imidazoles, also inhibit ergosterol : Clotrimazole(Gyne-Lotrimin), Miconazole(Monistat), Ketoconazole Figure MM04: Candida albicans Figure 21A: Candida albicans Diseases: skin • Thrush• Inflammation of mouth/ throat ( creamy coating on tongue) • Frequently occurs in newborns/ people with AIDS • Treatment: oral suspensions of gentian violet and nystatin • Yogurt with active cultures of lactobacillus Figure 21B: Oral candidiasis Courtesy of CDC Basidiomycota • Club fungi • Visible fruiting bodies: mushroom • Great decomposers- cellulose produced • Ex: Coprinus • Structure • Septate hyphae • Fungi that produces mushrooms • Nutritional • Symbiosis/parasite/ great decomposers • Reproduction • Sexual- fusion of +/- formation, fruiting structure • basidiospores-formed externally on base pedestal-basidium • 4 basidiospores per basidium • Asexual- Some basidiomycota produce asexual conidiospores Boletus santanas. Puffball mushroom Courtesy of Jeffrey Pommerville Fairy ring Basidiomycota • Underside of the cap is lined with “ gills” on which clubshaped basidia are formed, on which haploid basidiospores are produced • When mycelia of different mating types come into contact, they fuse into heterokaryon containing genetically different haploid nuclei Mushroom gills Courtesy of Jeffrey Pommerville SEM of mushroom gills © Dr. Richard Kessel & Dr. Gene Shih/Visuals Unlimited SEM of basidiospores © Eye of Science/Photo Researchers, Inc. • The life cycle of a basidiomycete alternates a haploid generation with a prolonged stage in which two nuclei (dikaryon) are present in the hyphae. Figure 5.32 Disease: mycotoxins • Produce mycotoxins: affect peripheral parasympathetic nervous system, hallucinations, condition resembling alcohol intoxication • Amanita phalloides- 90% of deaths from eating poisonous mushrooms: amatoxins, phalatoxins • A) amatoxin: alpha amanitin- hallucinogensource much poisoning/ causes diarrhea • B) phalatoxin: phalloidin- severe liver damage Amanita phalloides Microsporidia • Unicellular fungi; obligate intracellular parasites • They lack mitochondria, peroxisomes, and centrioles, but their spores release a unique polar tubule that pierces the host cell membrane to allow the fungus to gain entry into the cell. • A number are human pathogens, and infections with microsporidia are called microsporidiosis. • Ex: Enterocystozoan bieneusi- diarrhea, cholecystitis (inflammation of the gall bladder), respiratory illness. • (credit “Ascomycota”: modification of work by Dr. Lucille Georg, Centers for Disease Control and Prevention; credit “Microsporidia”: modification of work by Centers for Disease Control and Prevention) Figure 5.33 antifungals • Difficult to design because fungi are eukaryotes Antifungal • Polyenes • Bind to ergosterol, a sterol found exclusively in fungal plasma membrane • Its binding causes leakage of cell’s contents • Nystatin- primarily Candida albicans infections • Amphotericin B-serious systemic fungal infections: Aspergillus, Cryptococcus, Candida Antifungal • Imidazoles • Inhibit ergosterol biosynthesis in fungal membrane • Clotrimazole(GyneLotrimin) Candida skin infections • Miconazole(Micatin) athlete’s foot • Monistat yeast infections • Ketoconazole fungal infections in immunocompromised patients(HIV) Antifungal • Echinocandins • Inhibit biosynthesis fungal cell wall • Caspofungin- Candida, Aspergillus Antifungal • Flucytosine • Converted in fungal cells to fluorouracil(5-FU) , which becomes incorporated into RNA • Inhibits DNA/ RNA synthesis • Stops transcription/ translation, making organism non-functional • Active against systemic fungal infections of Candida and Cryptococcus • Used in combination with amphotericin B Antifungal • Griseofulvin • Interferes with mitosis by binding to microtubules • Used for ringworm(Microsporon, Trycophyton) and Athlete’s foot( Trycophyton)