Mycology

• Arthrospores are a type of asexual spore produced by fungi that are formed by the fragmentation of hyphae.
• Fungi


  Specialized discipline in the field of biology concerned with the study of fungi
• Fungi were considered relatively insignificant causes of infection historically
• During the early and mid 20th century, fungi began to be recognized as important causes of disease
• Reasons for the recognition of fungi as important causes of disease

  • Changes in patient profiles
  • Environment
• Laboratories should be equipped
• Fungi are generally not communicable through person-to-person transmission
• Humans are accidental hosts for fungi
• Ways in which humans can be hosts for fungi

  • Inhalation
  • Introduction into tissue by trauma
• Humans are relatively resistant to fungi except for cases caused by dimorphic fungi
• Old "harmless" saprophytic molds are now implicated in serious diseases
• Geographical distribution of fungi

  • Coccidioides immitis, a dimorphic fungi, is usually found only in the US (desert Southwest, Northern Mexico, and Central America)
  • Opportunistic pathogens (Candida, Aspergillus spp.) are found worldwide, everywhere, ubiquitous, can even be found in sea water and in the Arctic ice
• Fungi


  Composed of a vast array of organisms that are unique compared with plants and animals
• Types of fungi


  • Mushrooms, rusts, and smuts, molds and mildews, yeasts
• Mushrooms


  Various fungi that produce a fleshy fruiting body, consisting of a stalk with an umbrella-shaped cap
• Edible mushrooms


  Any of such fungi that are edible, especially the widely cultivated species Agaricus bisporus
• RUSTS


  • Plant disease caused by a fungus of the Class Uredinomycetes
  • Spots or pustules bearing masses of powdery spores which are usually rust colored, yellow, or brown
• SMUTS


  • Plant disease caused by order Ustilaginales
  • Affects mostly cereals and other grasses
  • Formation of masses of spores showing distortions
• MILDEW


  • A specific kind of mold
  • Usually with a flat growth habit
  • Surface fungi that can easily be identified as a patch of gray or even white fungus lying on the surface of a moist area
• MOLD


  • A fungi that contains multiple identical nuclei
  • It grows in the form of hyphae or filaments
  • Can be black or green and is often the result of a much larger infestation
• Fungi are eukaryotic microorganisms classified as members of the fungus kingdom
• There are 1,500 species of fungi currently identified, estimated to constitute 1% of all described fungal species
• Fungi are the organism of choice for the production of alcoholic beverages, bread, and a large variety of industrial products
• Fungi


  • Aerobic
  • Nucleated
  • Achlorophyllous
  • Mostly saprophytic
  • Cell wall component: CHITIN
  • Cell membrane component: ERGOSTEROL
  • Reproduction by means of spores produced sexually or asexually
• Two groups of fungi based on appearance of colonies

  • YEASTS: Produces moist, creamy opaque or pasty colonies on media
  • MOLDS: Filamentous fungi producing fluffy, cottony, woolly, or powdery colonies
• DIMORPHIC FUNGI


  • At room temperature (25°C), it grows as a mold. At body temperature (37°C), it grows as a yeast
• POLYMORPHIC FUNGI


  • Fungi having more than one independent form or spore stage in their life cycle
• YEASTS


  • Single-celled structures with thick cell wall
  • Usually multiply asexually by budding, sometimes called a BLASTOSPORE
  • The process of budding is mitotic
• HYPHAE


  • Long, slender, branching tubes generally 3-4 microns in diameter
  • Hyphae with crosswalls (SEPTATE HYPHAE)
  • Hyphae without crosswalls (COENOCYTIC HYPHAE or NON-SEPTATE HYPHAE)
  • Mass of hyphae (MYCELIUM)
• SPORES


  • Functionally similar to seeds of higher plants
  • Two types of spores: Sexual Spores, Mechanism is the same as sex
• Types of hyphae


  • Hyphae without crosswalls
  • Coenocytic Hyphae or Non-septate Hyphae
  • Septate Hyphae
• Mass of hyphae


  • Mycelium
  • Septate Hyphae
  • Coenocytic Hyphae or Non-septate Hyphae
  • Mycelium
• Spores are functionally similar to seeds of higher plants
• Types of spores


  • Sexual Spores
  • Asexual spores
• Mechanism of sexual spores

  Same as sexual reproduction having two parent cells
• Mechanism of asexual spores


  Division of one parent cell
• Mechanism of asexual spores


  Parent cell produces many spores identical to parent cell
• Asexual Reproduction


  1. Binary fission

  2. Budding

  3. Fragmentation

  4. Vegetative Reproduction

  5. Spore Formation
• Ascospore is a spore contained in an ascus or that was produced inside an ascus
• Basidiospore is produced by basidia and the basidium exists at the tip of hyphae expanding to form a vase or club