1Eukaryotic Microbial Diversity

• Early attempts at taxonomy: all plants and animals• Whitaker scheme (late 20th century)

– Five kingdoms– Modified by Woese’s work on rRNA

• Three Domains, one of which is Eukaryotes

• Protista: the grab bag Kingdom– Always recognized as a highly diverse group– In new schemes, split into 7 kingdoms

• Since the application of molecular biology, taxonomy of all things constantly changing.

2Eukaryotes 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

3Microbial 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

4Kingdom Protista

• Highly diverse group of organisms– Size range from 5 µm to several

meters (kelp)– 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

library.thinkquest.org/ 12413/protist.html

5Some protozoal terminology

• Macronucleus and micronucleus– Two type of nuclei differing in size and function.

• Cyst: a resting stage similar to a spore with a thick wall and low level of metabolism.

• Trophozoite: stage in life cycle during which the microbe is feeding and growing.

• Merozoite: Small cells with a single nuclei produced during schizogony.– Large, multinucleated cell undergoes cytokinesis to

produce multiple daughter cells (merozoites)

6Plant-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

7Fungus-like • Water molds• Slime molds

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

Animal-like protists

Capable of ingesting their food.

Found among many different groups, so not good for taxonomy.

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

8Breaking up the Protista: various algae, slime molds, and Protozoa

• What are the characteristics of Protozoa?

• Unicellular eukaryotes

• Lack a cell wall

• Require moist environments (water, damp soil, etc)

• 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

9How to classify?

• Cell ultrastructure and molecular analysis becoming the main methods used for classification.– Suggests that several kingdoms would be appropriate.– Alternative scheme, keep the kingdom Protista, classify

protozoa into several phyla

• Typical textbook: – 4 groups of protozoa– Algae– Slime molds– Water molds

10Classification of Protozoa

• Alveolates– Ciliates– Apicomplexans– Dinoflagellates

• Amoebae– Shelled and unshelled

• Euglenozoa– Ameobae– Euglenoids– Kinetoplastids

• Archaezoa– Diplomonadida– Parabasala

http://www.jracademy.com/~mlechner/archive1999/paramecium.JPG

11Protozoa: details and examples

• Alveolates• Possess alveoli: small membrane-bound cavities of

unknown function (classification by ultrastructure)– Ciliates: move by cilia, short flagella-like appendages

• Includes disease-causing Balantidium– Apicomplexans: have a complex of specialized

organelles at the apices (corners, tips) of the cells• Generally have complex life cycles• Include Plasmodium (malaria), Toxoplasma

(toxoplasmosis).

12Apicomplexans

Complex structure of organelles involved in infection.

http://cgdc3.igmors.u-psud.fr/microbiologie/apicomplexans_fichiers/image002.jpg

13Alveolates continued

– Dinoflagellates• Large group of plantlike protozoa, have

photosynthetic pigments (chlorophylls), cellulosic cell walls, store sugars as starch.

• RNA sequences show relationship to other aveolates, not to plants.

• Large portion of fresh water and marine plankton• Some encased in silica• Some bioluminescent or produce red pigments• Some produce dangerous neurotoxins

14Amoebae

• Amoebae have 2 main characteristics– Move and feed using pseudopodia

• Cytoskeleton aids extension of cell membrane, cytoplasmic streaming.

– Lack mitochondria

• Some have loose shells; some form cysts.– Fossilized shells major component in some limestones.

• Some “ameobae” are classified in another group.

• Entamoeba: example of disease-causing amoeba.

15Euglenozoa

– United by similar RNA sequences– Not particularly similar otherwise. Have mitochondria.

• Amoebae: move by pseudopodia– Including disease-causing Naegleria and Acanthameoba

• Euglenoids: Euglena and similar microbes– Photoautrophs, but: no cell walls, motile by flagella and

other means, store paramylon instead of starch, and can grow heterotrophically in the dark. Not plants!

• Kinetoplastids: mitochondrial DNA forms kinetoplast

– Includes Trypanosma, a pathogen

16Archaezoa– Lack mitochondria and some other organelles– Thought to be old, hence the name (“Archae-”)– But have mitochondrial genes in nucleus.

• Diplomonadida: 2 nuclei plus flagella– Includes pathogen Giardia, forms cysts, causes diarrhea

• Parabasala: Single nucleus plus parabasal body. – Wood digesting microbe of termite gut.– Trichomonas,

inhabits vagina, potential STD

http://www.mhhe.com/socscience/sex/common/ibank/ibank/0149.jpg

17Algae

• Green algae– Ancestors of plants

• Red algae– Mostly marine– Source of food thickeners carrageenan and agar

• Chrysophyta (golden algae, diatoms, etc)– Diatoms: major component of phytoplankton

• Diatomaceous earth as abrasives, gardening tools

• Brown algae– Common seaweeds, kelps http://habitatnews.nus.edu.sg/

news/chekjawa/ria/photos/r119.jpg

18Water Molds and Slime Molds

• Water molds– Similar to fungi except for 4 major differences; – 2 of 4: cellulose, not chitin in cell wall; motile spores– Phytophthora: Irish potato blight, sudden oak death

• Slime molds– Acellular slime molds: The Blob, giant multi-nucleated

cell; reproduces into amoebae that are amphibious– Cellular slime molds, e.g. Dictyostelium: unicellular,

aggregate into slug-like structure, model for primitive development and differentiation.

19Fungi

• 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

20Fungi 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

21Impacts 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)

22Classification 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.

23Classification-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... www.butte.cc.ca.us/.../ fungi.unks.html

Zygospore

sporangia

24Classification-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

www.ent.iastate.edu/.../ aspergillus_ear_rot.html

Ascusconidia

25Classification-4

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.

www.birdsasart.com/ bn106.htm www.fishing-in-wales.com/. ../fungi/parasol.htm

Close-up of gills