Bacteria1 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’

Bacteria2 Classification based upon anatomical features 3 common shapes Some unusual shapes also:

Bacteria3 Classification based upon anatomical features Other unusual bacteria Spirochetes Cell wall-less Stalked Filamentous Myxobacteria fruiting bodiesStreptomyces

Bacteria4 Classification based upon staining Gram Positive vs Gram Negative Hans Christian Gram Crystal violet Gram positive structure -- thick layer of peptidoglycan Gram negative structure -- inner vs outer membranes -- lipopolysaccharides and endotoxins Acid fast staining -- Mycobacterium Penicillin action Effect of penicillin

Bacteria5 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)

Bacteria6 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 angert-lab/epulopiscium.cfm

Bacteria7 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)

Bacteria8 Cell Membrane Structure Phospholipid bilayers Membrane proteins Membrane fluidity Membranes of thermophilic archaebacteria

Bacteria9 Bacterial Flagella Prokaryotic vs eukaryotic Arrangements monotrichous lopho- amphi- peri- How do we know movement is rotational? Bacterial Flagella

Bacteria10 How do flagellated bacteria move? ‘Run and Tumble’ pattern Chromatium motility

Bacteria11 Spirochetes -- very strange structure -- e.g., Borrelia, Treponema Axial filaments Outer sheath Motility Borrelia Movement

Bacteria12 Fimbriae and Pili Fimbriae adhesion to surfaces Pili (pilus) genetic recombination other functions?

Bacteria13 The glycocalyx Functions adherence virulence prevent desiccation Composition Capsule layers vs Slime layers “xantham gum”(Xanthomonas) Strep Pneumo

Bacteria14 Endospores Formation and regrowth Special properties? -- desiccated -- DNA binding proteins -- Ca-dipicolinic acid Magnetotactic bacteria -- possess magnetosomes Endospore formation Magnetotactic Bacteria