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Bacteria Chapter 5 Classification of bacteria is ‘murky’ A “Muddle in the Middle” Few distinctive characteristics

Bacteria Chapter 5 Classification of bacteria is ‘murky’ A “Muddle in the Middle” Few distinctive characteristics Genetically promiscuous Traditional classification: anatomical features staining characteristics metabolic properties Newer approach Genetic analysis

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Bacteria Chapter 5 Classification of bacteria is ‘murky’ A “Muddle in the Middle” Few distinctive characteristics

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  1. Bacteria Chapter 5 Classification of bacteria is ‘murky’ A “Muddle in the Middle” Few distinctive characteristics Genetically promiscuous Traditional classification: anatomical features staining characteristics metabolic properties Newer approach Genetic analysis Bergey’s manual is the ‘Bible’ Bacteria

  2. Classification based upon anatomical features 3 common shapes Some unusual shapes also: Bacteria

  3. Classification based upon anatomical features Other unusual bacteria Spirochetes Cell wall-less Stalked Filamentous Streptomyces Myxobacteria fruiting bodies Bacteria

  4. Classification based upon staining Gram Positive vs Gram Negative Hans Christian Gram -- 1884 -- Crystal violet Gram positive structure -- thick layer of peptidoglycan Gram negative structure -- inner vs outer membranes -- lipopolysaccharides and endotoxins Acid fast staining -- Mycobacterium Effect of penicillin Penicillin action Bacteria

  5. Classification based upon metabolism -- will explore further later Heterotrophic Autotrophic Photosynthetic bacteria -- cyanobacteria -- purple sulfur bacteria Chemoautotrophic ‘Metabolically defective’ Rickettsia Chlamydia Rocky Mountain Rocky Mountain Spotted fever wood tick R. rickettsii Image from (and good source for more about Chlamydia) http://www.chlamydiae.com/docs/biology/biol_devcycle.asp Bacteria

  6. Why are bacteria so small? Size affects ‘surface to volume’ ratio Advantages of large S/V: diffusion rates metabolic rates reproductive rates Limits to size reduction? ‘defective’ bacteria Really big bacteria? -- Epulopiscium fishelsoni Epulopiscium web site http://www.micro.cornell.edu/cals/micro/research/labs/ angert-lab/epulopiscium.cfm Bacteria

  7. Why study Bacterial Cell Structure? Mechanisms of virulence Drug development Identification Some cell exterior structures cell membrane (lipid bilayer) cell wall (Gram-pos vs Gram-neg) glycocalyx (capsule vs slime layer) flagellum (prokaryotic vs eukaryotic) pilus (adhesion vs sex) Bacteria

  8. Cell Membrane Structure Phospholipid bilayers Membrane proteins Membrane fluidity Membranes of thermophilic archaebacteria Bacteria

  9. Bacterial Flagella Prokaryotic vs eukaryotic Arrangements monotrichous lopho- amphi- peri- How do we know movement is rotational? Bacterial Flagella Bacteria

  10. How do flagellated bacteria move? ‘Run and Tumble’ pattern Chromatium motility Bacteria

  11. Spirochetes -- very strange structure -- e.g., Borrelia, Treponema Axial filaments Outer sheath Motility Borrelia Movement Bacteria

  12. Fimbriae and Pili Fimbriae adhesion to surfaces Pili (pilus) genetic recombination other functions? Bacteria

  13. The glycocalyx Functions adherence virulence prevent desiccation Composition Capsule layers vs Slime layers “xantham gum”(Xanthomonas) Strep Pneumo Bacteria

  14. Endospores Formation and regrowth Special properties? -- desiccated -- DNA binding proteins -- Ca-dipicolinic acid Magnetotactic bacteria -- possess magnetosomes Endospore formation Magnetotactic Bacteria Bacteria

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