1 Eukaryotic 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.

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 Kingdom 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

5 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

6 Fungus-like Water molds Slime molds Animal-like protists Capable of ingesting their food. Found among many different groups, so not good for taxonomy.

7 How 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

8 Classification of Protozoa Alveolates –Ciliates –Apicomplexans –Dinoflagellates Amoebae –Shelled and unshelled Euglenozoa –Ameobae –Euglenoids –Kinetoplastids Archaezoa –Diplomonadida –Parabasala er/archive1999/paramecium.JPG

9 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

10 Some protozoal terminology 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) Cytoplasmic streaming. –Cytoskeleton aids extension of cell membrane

11 Algae 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 /chekjawa/ria/photos/r119.jpg

12 Water 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.

13 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

14 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

15 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)

16 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.

Evolution of the fungi

Classification & Phylogeny motile spores zygosporangia asci basidia

Fungi Classification of fungal diseases (mycoses) Superficial, cutaneous, subcutaneous Superficial, cutaneous, subcutaneous Systemic and opportunistic Systemic and opportunistic Poisoning and allergies Poisoning and allergies Treatment Treatment Azole drugs, amphotericin B, others Azole drugs, amphotericin B, others

Opportunistic infections Aspergillus (aspergillosis) Aspergillus (aspergillosis) Variety of species, very common in soil, plant materials Variety of species, very common in soil, plant materials Serious infections in immunocompromised Serious infections in immunocompromised Allergies to A. fumigatus Allergies to A. fumigatus Poisoning from aflatoxin from A. flavus Poisoning from aflatoxin from A. flavus Candida (candidiasis)- normal microbiota Candida (candidiasis)- normal microbiota Cause of vaginal infections, diaper rash, thrush Cause of vaginal infections, diaper rash, thrush Capable of infecting any part of the body Capable of infecting any part of the body Dangerous in cancer patients, HIV infections, etc. Dangerous in cancer patients, HIV infections, etc.

Opportunists-2 Cryptococcus neoformans Cryptococcus neoformans Inhalation of spores Inhalation of spores Can infect many parts, but has predilection for CNS Can infect many parts, but has predilection for CNS Particularly serious in AIDS Particularly serious in AIDS Pneumocystis carinii Pneumocystis carinii Very protozoan like, but is a fungus Very protozoan like, but is a fungus Most cases associated with AIDS Most cases associated with AIDS Serious lung infections: PCP (P. carinii pneumonia) Serious lung infections: PCP (P. carinii pneumonia)

22 Microbes and diseases: what to study-1 1. Causative microbe: name, morphology (shape, size, Gram stain, etc.), physiology (aerobe, anaerobe, etc) and some info on classification (what's it related to?) 2. Pathogenesis and clinical disease: what disease does it cause (signs and symptoms) and how does it do it (capsule, toxins..)? 3. Transmission and epidemiology: how do you get the disease?

23 Microbes and diseases: what to study-2 4. Diagnosis: How does the lab usually identify the causative agent? 5. Treatment: antibiotics prescribed (or not- no cell wall, no penicillin) or other treatment (oral rehydration therapy for cholera). 6. Prevention and control (stop the spread; condoms, kill urban rats..)