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Eukaryotic Microbial Diversity Overview of taxonomy. Early attempts at taxonomy: all plants and animals Some still refer to bacteria as “flora” Whitaker scheme (late 20th century) Five kingdoms: Monera (bacteria) and 4 eukaryotic kingdoms Carl Woese’s work on rRNA

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eukaryotic microbial diversity overview of taxonomy
Eukaryotic Microbial DiversityOverview of taxonomy
  • Early attempts at taxonomy: all plants and animals
    • Some still refer to bacteria as “flora”
  • Whitaker scheme (late 20th century)
    • Five kingdoms: Monera (bacteria) and 4 eukaryotic kingdoms
  • Carl Woese’s work on rRNA
      • Three Domains: Archaebacteria, Eubacteria, and Eukaryotes
  • The four eukaryotic kngdoms:
    • Animals, plants, fungi, and protists
      • Grouped by similar structure, physiology, and behavior
      • The boundaries of these kingdoms now being altered by research in molecular biology.
eukaryotes vs prokaryotes
Eukaryotes vs. prokaryotes
  • Eukaryotes are larger
  • Eukaryotes have membrane-bound organelles
    • Nucleus, mitochondria, membrane systems
    • Larger size requires functional compartments
    • Mitochondria once bacteria? So same size!

microbial eukaryotes
Microbial eukaryotes
  • Animals
    • Parasitic worms; studied by Parasitologists
  • Fungi
    • Yeasts and molds, studied by Mycologists
    • Several types can cause human disease
  • Protists
    • Unicellular eukaryotes with many different characteristics. Also studied by Parasitologists.
    • Some cause human disease
  • Plants: not of particular interest other than hosts
protista the grab bag kingdom
Protista: the grab bag Kingdom
  • Protists are generally microscopic, unicellular, eukaryotes.
    • Historically, classified together because of their differences from other organisms
    • Always recognized as a highly diverse group
  • Since the application of molecular biology, taxonomy of all things constantly changing.
    • In new schemes, Protista split into 7 kingdoms, they are that different from one another and from other organisms
kingdom protista
Kingdom Protista
  • Highly diverse group of organisms
    • Size range from 5 µm to 5 mm
    • Defined more by what they aren’t
    • Nutrient/energy acquisition ranges from photosynthesis to predatory to detrivores
    • Important in many food webs
      • Provide link between bacteria and larger organisms
  • Learn simple, unofficial taxonomy 12413/protist.html

plant like protists
Plant-like Protists
  • Contain chloroplasts
  • Representatives
    • Diatoms (right).
      • Diatomaceous earth = fossilized diatoms: abrasives and slug repellants.
    • Red, brown, yellow algae
      • Seaweed, source of agar
    • Dinoflagellates
      • Neurotoxins and red tide article.php/534.html

fungus like
  • Water molds
    • Motile spores, unlike true fungi
    • Phytophora infestans: caused the great Irish potato blight and extensive emigration.
  • Slime molds
    • Cellular slime mold, individual amoebas that aggregate to form fruiting body
    • Plasmodial slime mold: the blob. Similar life cycle.

the protozoa
The Protozoa
  • Most medically important protists are protozoa
    • Unicellular eukaryotes
    • Lack a cell wall
    • Require moist environments (water, damp soil, etc)
    • Mostly Animal-like
  • Great amounts of diversity
    • Locomotion: float, cilia, flagella, pseudopodia
    • Nutrition: chemoheterotrophs, photoautotrophs, either
    • Simple to complex life cycles, reproduction
    • Different cell organelles, some lack mitochondria
animal like protists
Animal-like protists
  • Most likely to cause human disease
  • Typically have a complex life cycle
    • Esp. sporozoans, involving several stages and multiple hosts
  • Classified mostly according to type of motility
    • Amoebas (cytoplasmic streaming)
    • Ciliates (cilia)
    • Flagellates (flagella)
    • Sporozoans (non-motile)

  • Amoebae move and feed using pseudopodia
      • Cytoskeleton aids extension of cell membrane, cytoplasmic streaming.
  • Some have loose shells; some form cysts.
    • Fossilized shells major component in some limestones.
  • Protists with the structure of “ameobae” are classified in more than one group.
  • Most live in the environment, eating bacteria
    • Entamoeba, Naegleria : examples of disease-causing amoebae.
other protozoa
Other Protozoa
  • Ciliates:
    • move by cilia, short flagella-like appendages
    • Includes disease-causing Balantidium
  • Flagellates:
    • Move using flagella
    • Some disease-causing flagellates include
      • Giardia, forms cysts, causes diarrhea
      • Trichomonas, inhabits vagina, potential STD
  • Sporozoans: Generally have complex life cycles
      • Include Plasmodium (malaria), Toxoplasma (toxoplasmosis)
  • Mycology: the study of fungi
  • Fungi are mostly saprophytes, all heterotrophs
    • Saprophytes: decay non-living organic matter
      • Fungi are the kings of decomposition
    • Heterotrophs: use pre-formed organic matter
      • Not autotrophs, not photosynthetic
  • Fungi grow into, through their food
    • Release extracellular enzymes, break down polymers into LMW compounds for transport
fungi terminology and structure
Fungi terminology and structure
  • Hypha (singular) hyphae (plural): thread
    • Hyphae may be partially separated into cells or not at all (ceonocytic).
      • Cytoplasm is continuous throughout hypha
  • Mycelium (plural mycelia): a mass of hyphae
    • Like a bacterial colony except really all one organism.
  • Some fungi are molds, some are yeasts
    • Yeasts are oval, unicellular
    • Dimorphic: able to grow as either form.
      • Typical of some disease-causing fungi
impacts of fungi
Impacts of Fungi
  • Disease: mycosis (plural mycoses)
    • Superficial (on hairs, nails)
    • Cutaneous (dermatophytes, in skin (athlete’s foot)
    • Subcutaneous (deeper into skin)
    • Systemic (in deeper tissues, usually via lungs)
      • Opportunists: serious disease when immune system is depressed.
  • Antibiotic production
    • Penicillium, Cephalosporium
  • Decomposition; Food industry (soy sauce)
classification of fungi
Classification of fungi
  • By sexual reproductive structures
  • Fungi reproduce both asexually and sexually
  • Deuteromycota = Fungi Imperfecti
    • No longer a valid classification
    • Contained fungi that couldn’t be coaxed into having sex
    • Through morphological and molecular means (e.g. DNA analysis), being distributed into the other 3 phyla of fungi.
classification 2
  • Zygomycota: produce zygospores
    • Example: Rhizopus
    • Fusion of hyphae (haploid) of opposite mating types produces zygospore (diploid).
    • Zygospore produces a zygosporangium with haploid spores that are released.
    • Asexually, sporangium containing spores.


Zygospore images/332/Zygomycota/ fungi.unks.html

classification 3
  • Ascomycota: the sac fungi
  • Sexual spores produced inside an ascus (sac)
  • Asexual spores are called conidiospores or conidia (singular conidium)
  • Many types of common molds are ascomycetes.


conidia nwfg/ascus.htm fungos%20e%20micoses.htm aspergillus_ear_rot.html

classification 31
  • Basidiomycota: the club fungi or mushrooms
  • After extensive growth of hyphae, opposite mating types fuse and above ground mushroom is formed.
  • Sexual spores are called basidiospores; asexual conidia can also be formed.

Close-up of gills bn106.htm ../fungi/parasol.htm