myco 1

• Mycology

  The study of fungi
• Mycology


  • Includes research of genetic and biochemical properties and use in medicine and food
• Mykes


  Greek word meaning mushrooms
• Raymond Sabouraud published his book Les Teignes, a comprehensive study of dermatophytic fungi


  1910

  
• Raymond Sabouraud


  Father of Medical Mycology
• Beneficial activities of fungi

  • Decomposition
  • Antibiotics
  • Food production
• Food production


  • Mushrooms
  • Truffles
  • Bread making
  • Cheese - blue cheese Roquefort, Camembert
  • Fermentation of sugars to produce ethyl alcohol & CO2 (Beers and Wines)
  • Industrial production - antibiotics, alcohols, and vaccines
• Mycorrhizae


  Fungus roots that supply water, phosphorus & nitrate to plants, while the fungus gets sugars from the plants
• Harmful Activities of Fungi

  • Destruction of materials
  • Spoilage
  • Destruction of crops
  • Fungal infections
  • Allergies
  • Mycotoxicosis
• Fungi


  Eukaryotic organisms, 2 major groups: yeasts and molds, lack chlorophyll, have cell walls, filamentous structures called hyphae, and produce spores, grow as saprophytes and decompose dead organic matter, 100,000 to 200,000 species with 300 species pathogenic for humans
• Fungi


  • Heterotrophic, use complex organic compounds as source of carbon, lack chlorophyll, live embedded in a food source or medium, obtain nourishment by secreting enzymes for external digestion and absorbing the released nutrients
• Fungal Metabolism


  Most fungi are saprophytes, obtaining their energy from dead organic material by secreting hydrolytic enzymes to break down external substrates which are then absorbed to produce energy
• Growth Requirements


  • Moisture & oxygen (most are obligate aerobes), Temperature (0-60 deg C, optimum 25-30 deg C), pH (1-12, optimum 7)
• Habitat


  The usual habitat is the environment and where organic matter is available, flourish well in moist, dark, and warm conditions, some grow as parasites of plants and animals
• Laboratory culture


  • Fungi are usually cultured at 30 oC, on culture media designed to inhibit bacterial growth containing minimal nutrients and antibiotics, growth of most yeasts and molds are visible within several days, fungi of medical importance can take several weeks to form visible colonies
• Reproduction


  • Asexual (anamorph)
  • Sexual (teleomorph)
• Asexual Reproduction


  • Fragmentation, Budding, Spores
• Sexual Reproduction


  • Carried out by diffusion of compatible nuclei from two parent at a definite state in the life cycle, includes Plasmogamy (fusion of protoplasm), Karyogamy (fusion of nucleus), and Meiosis (reductional nuclear division)
• Sexual Spores


  • Ascospore
  • Basidiospore
  • Zygospore
  • Oospore
• Fungal Morphology


  • Yeasts (unicellular, reproduce by budding),
  • Molds (multicellular, filamentous structures called hyphae, mass of hyphae is called mycelia, pattern of branching aids to morphological identification, mycelia that do not have septa are called coenocytic),
  • Dimorphic (occur in both yeast and mycelial forms)

  
• Yeast Characteristics


  • Microscopically appear as oval structures similar to bacterial cocci but much larger, reproduce by budding, may form pseudohyphae, colonies are soft, glabrous/waxy, shiny, slimy, mucoid, creamy, opaque, yellowish, or white
• Yeast Capsules


  • One genus of yeasts known as Cryptococcus produces a large polysaccharide capsule
  • Capsule is seen by negative stain using India ink that cannot penetrate the capsule
• Mold Characteristics


  • Multicellular, variety of colors, look fuzzy or cottonlike, can develop tiny spores that ride in the air and spread by air currents, grow on surface of food
• Fungal Hyphae


  • Septate (divided into cells by cross walls) or non-septate (coenocytic), hyaline (colorless, clear) or dematiaceous (pigmented, dark in color, usually brown or gray to black)

  
• Mold Forms


  • Exogenously formed conidia may develop directly from the hyphae or on a special stalk-like structure called a conidiophore, macroconidia and microconidia indicate the size and complexity of these conidia
• Hyphae


  • Arise from hyphae
  • Bear a "Medusa head"
• Conidia


  Reproductive crop
• Characterization of Fungal Colonies


  • Texture
  • Topography
  • Surface and reverse colony colors
  • Production of diffusible pigment from the colony into growth medium
• Growth of mold colony on laboratory agar medium


  1. Grow above the surface of the agar

  2. Form most of the visible part of the colony

  3. Grow in or on the medium

  4. Absorb nutrients from the medium
• Texture of fungal colony

  Determined by the height of aerial hyphae from the surface of a colony

  
• Cottony texture


  • Develop when colonies produce long aerial hyphae
  • Resembling cotton candy
  • Also called woolly, floccose
• Velvety texture


  • Resemble plush or velvet fabric or pig-skin
  • Have short aerial hyphae
  • Few conidia or spores
  • Also called 'suede'
• Powdery / Granular texture


  • Short aerial mycelium
  • Sporulate heavily
  • Powdery like flour/talcum
  • If more coarse than powdery - granular
• Glabrous texture


  • Little if any aerial mycelium
  • Skin-like (hairless)
  • Also called leathery or waxy
• Colonial topography


  Describes the various designs of hills and valleys seen on fungal cultures (the way the colony surface is arranged)
• Colony color


  Describes color of colonial surface and reverse
• Dimorphic fungi


  Grow as molds in the saprobic or environmental phase and as yeast in the parasitic phase
• Kingdoms of living things

  • Fungi
  • Others
• The fungi are in the Kingdom Fungi
• This common characteristic is responsible for the therapeutic dilemma in anti-mycotic therapy