Eukaryotic Microbial Diversity Overview of taxonomy

1. 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.

2. 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! http://www.earthlife.net/images/eury-cell.gif

3. 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

4. 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

5. 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 library.thinkquest.org/ 12413/protist.html

6. 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 http://www.bhikku.net/archives/03/img/diatoms.JPG www.enviroliteracy.org/ article.php/534.html

7. 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. http://en.wikipedia.org/wiki/Slime_mold

8. 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

9. 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) http://ar.geocities.com/seti_argentina/estamos_solos/ameba.jpg

10. Amoebae • 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.

11. 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)

12. Fungi • 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

13. 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

14. 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)

15. 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.

16. 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. sporangia Zygospore botit.botany.wisc.edu/ images/332/Zygomycota/Z...www.butte.cc.ca.us/.../ fungi.unks.html

17. 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. Ascus conidia fungus.org.uk/ nwfg/ascus.htm inseto.rc.unesp.br/.../ fungos%20e%20micoses.htm www.ent.iastate.edu/.../ aspergillus_ear_rot.html

18. Classification-3 • 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 www.birdsasart.com/ bn106.htm www.fishing-in-wales.com/. ../fungi/parasol.htm