1 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 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!

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 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.

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)

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

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

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. bn106.htm Close- up of gills