Bacteria &; prokaryotes

Bacterial and prokaryotes

1. Bacteria 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’

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

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

4. 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

5. 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

6. 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

7. 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)

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

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

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

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

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

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

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