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Ascomycota (continued) MIKROSKOPIK

KULIAH 7. Ascomycota (continued) MIKROSKOPIK. YEAST, RAGI, KHAMIR… DLL. PEMBAGIAN ASCOMYCOTA. Class 1: Laboulbeniomycetes parasitic attachments to arthropods. Class 2: Protoascomycetes lack of ascogenous hyphae and ascomata . Class 3: Euascomycetes

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Ascomycota (continued) MIKROSKOPIK

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  1. KULIAH 7 Ascomycota (continued)MIKROSKOPIK YEAST, RAGI, KHAMIR… DLL

  2. PEMBAGIAN ASCOMYCOTA Class 1: Laboulbeniomycetes parasitic attachments to arthropods. Class 2: Protoascomycetes lack of ascogenoushyphae and ascomata. Class 3: Euascomycetes most of the fungi which form ascomata. The orders are separated on the structure of the ascus and the manner of ascus opening.

  3. From Spatafora et al. 2006. A five-gene phylogeny of Pezizomycotina. Mycologia 98: 1018-1028

  4. Filamentous ascomycetes Sacccharomycetales Characterized by DNA sequence analysis Archiascomycetes Basidiomycetes Ascocarps; ascogenous hyphae; specialized ascus tip; conidia; Woronin bodies Absence of ascogenous hyphae and ascocarps; most asci without specialized tips Classification from Alexopoulos et al. 1996

  5. RAGI • Ascomycetous yeasts • Characterized by absence of ascogenoushyphae and ascocarps • Asci mostly prototunicate • Occur in slime fluxes, nectar, fresh or decaying fruit—able to grow in high osmotic conditions (high sugar content) • Others occur in soil, dung, water, digestive tracts of animals • Many species are symbiotic with insects

  6. Schizosaccharomyces

  7. Saccharaomyces

  8. Somatic structures • Yeast • A single-celled fungus that reproduces by budding (or fission) • Pseudomycelium • Series of cells adhering after budding

  9. Budding Bipolar Multilateral

  10. Asexual reproduction • Conidia • Arthrospores

  11. karyogamy plasmogamy budding copulation 2n somatic cells 1n somatic cells meiosis Mature ascus

  12. Identification • Microscopic appearance • Unicellular or budding • Size & shape of yeast cells • Multilateral or bipolar budding • Form, structure and mode of ascus formation • Ascospore shape

  13. Identification • Physiological tests—91 different tests • Ferment different sugars • Assimilation tests (carbon and nitrogen source) • Vitamin requirements • Growth at 37C • Growth in cyclohexamide • Hydrolyse urea • Form acid

  14. Importance • Brewing • Baking • Food production • Industrial applications • Model systems (S. cerevisiae) • Probiotics • Animal pathogens

  15. MICROSCOPIC (NON-YEAST)

  16. Eurotium • Aspergillusanamorph • Cleistothecia yellow to orange-red • Wall composed of single layer of flattened cells • Ascosporesflattened, usually with equatorial groove. Ascospore by D. Geiser From Hanlin, 1998. Illustrated Genera of Ascomycetes Vol II

  17. Emericella • Aspergillus anamorph • Cleistothecial wall surrounded by hülle cells • Ascospores small, colored, lens-shaped with flange From Hanlin, 1998. Illustrated Genera of Ascomycetes Vol II

  18. Emericella Hülle cells, D. Geiser

  19. Anamorphs--Aspergillus SEM by Charles Mims

  20. Eupenicillium • Penicilliumanamorph • Cleisothecia hard, white becoming colored (yellow, orange, brown) • Ascospores small, hyaline or yellowish, lens-shaped From Hanlin, 1998. Illustrated Genera of Ascomycetes Vol II

  21. Image by David Geiser

  22. Anamorphs--Penicillium phialides Branches (metulae)

  23. Talaromyces • Paecilomyces or Penicilliumanamorph • Cleistothecium whitish to bright yellow • Wall composed of interwoven hyphae • Ascospores ellipsoidal, with spiny walls From Hanlin, 1998. Illustrated Genera of AscomycetesVol II

  24. Anamorphs--Paecilomyces Divergent phialides with swollen base and long, tapering neck Colonies may be pink, purple, yellow, brown or white, but never green as in Penicillium spp.

  25. The good and the bad • Penicillium spp.—antibiotic production • Penicilliumroqueforti—blue cheese • Penicillium spp.—blue and green molds on bread, cheese, fruits, vegetables • Aspergillus flavus—aflatoxins (moldy peanuts) • A. flavus/A. niger--aspergillosis

  26. Penicillin • Penicillium notatum growing in Alexander Fleming’s Petri dish of Staphylococcus in 1928 led to the discovery of penicillin • Howard Florey & Ernest Chain (1939) began work on purification and trials • 1941—work moved to US (NRRL in Peoria, IL) to escape bombing in London (WWII) • Fermentation vessels and corn steep liquor • Mary Hunt (“Moldy Mary”) brought in P. chyrogenum on a melon • 1945—Fleming, Florey & Chain received Noble Prize

  27. Penicillium notatum Penicillin prevents cross-linking of small peptide chains in peptidoglycan, the main wall polymer in bacteria. Newly formed cells are abnormal in shape and susceptible to osmotic lysis.

  28. POWDERY MILDEW • Biotrophsof vascular plants • Biotroph: an obligate parasite growing on another living organism • 21 genera, 437 species infecting > 40,000 species of plants (mostly dicots) • Most species are host specific, a few are omnivorous, infecting hundreds of host species

  29. Powdery Mildew Symptoms Photo by Claudia Nitschwitz

  30. Characteristics • Mycelium is mostly superficial • Anchored to host epidermis by appressoria • Nutrients obtained via haustoria • Haustoria are intracellular structures • Overwinter as mycelium in infected buds or as ascomata • Asexual reproduction via conidia • Sexual reproduction via ascospores formed in cleistothecia

  31. Asexual reproduction • Erect, hyaline conidiophores are usually formed on superficial mycelium; • One-celled, hyaline thin-walled conidia are produced holoblastically in basipetal chains • One colony can produce > 30,000 conidia

  32. Conidia • Wind-dispersed • Germination can occur at low relative humidity • Germination involves germ tube, appressorium and penetration peg formation • Apex of penetration peg enlarges to form haustorium

  33. From APSnet.org

  34. appressorium Plasma membrane Penetration peg haustorium Host cytoplasm Plasma membrane Plant cell wall fungus

  35. Microsphaera alni anamorph on Vaccinium

  36. Sexual reproduction • Cleistothecia formed on superficial mycelium in late summer/early fall • Asci • Formed in basal layer • Globose to pyriform • Discharge of spore by rupture of ascus tip

  37. Asci/Ascospores • One to numerous asci/cleistothecium • Ascospores hyaline, one-celled, ovoid • 1-8 ascospores/ascus • Number of asci/cleistothecium is important character in identification

  38. From APSnet.org

  39. Identification • Anamorph type • Number of asci/ascocarp • Cleistothecial appendages • Mycelioid • Rigid • Spear-like with inflated base • With curled tips • With dichotomously branched tips

  40. Microsphaera alni cleistothecia

  41. Sawadaea bicornis cleistothecia

  42. Sawadaea bicornis cleistothecial appendages

  43. Mycelioid Appendages • Several asci/ascocarp: • Eryisiphe(100 spp) • Oidiumanamorph • One ascus/ascocarp: • Sphaerotheca (50 spp.) • Appendages with curled tips • Oidiumanamorph

  44. Dichotomously branched appendage tips • One ascus/ascocarp: • Podosphaera (12 spp.) • Oidiumanamorph • Several asci/ascocarp: • Sawadaea(6 spp.) • Oidiumanamorph

  45. Spear-like appendages--Phyllactinia • Ovulariopsisand Streptopodiumanamorphs

  46. Appendages with curled tips • Uncinula (81 spp) • Oidiumanamorph • Several asci/ascocarp

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