bacteria1 chapter 5 classification of bacteria is ‘murky’ a “muddle in the middle” few...
TRANSCRIPT
Bacteria 1
Bacteria Chapter 5
Classification of bacteria is ‘murky’
A “Muddle in the Middle”Few distinctive characteristicsGenetically promiscuous
Traditional classification:anatomical featuresstaining characteristicsmetabolic 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
Myxobacteria fruiting bodies Streptomyces
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
Penicillin action
Effect of penicillin
Bacteria 5
Classification based upon metabolism -- will explore further later
Heterotrophic
AutotrophicPhotosynthetic 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 ratesmetabolic ratesreproductive rates
Limits to size reduction?‘defective’ bacteria
Really big bacteria?-- Epulopiscium fishelsoni
Epulopiscium web sitehttp://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 structurescell 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 ofthermophilic archaebacteria
Bacteria 9
Bacterial Flagella
Prokaryotic vs eukaryotic
Arrangementsmonotrichous
lopho-
amphi-
peri-
How do we know movementis rotational?
Bacterial Flagella
Bacteria 10
How do flagellatedbacteria move?
‘Run and Tumble’ patternChromatium 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
Functionsadherencevirulenceprevent desiccation
Composition
Capsule layersvs
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