1. Characterizing and Classifying prokaryotes chapter 11

2. Prokaryotes Most diverse group of organisms Habitats
All possible habitats are exploited by some sort of prokaryote
Only a few capable of colonizing humans and causing disease

3. Morphology of Prokaryotic Cells
Figure 11.1

4. Arrangements of Prokaryotic Cells
Result from two aspects of division during binary fission
Planes in which cells divide
Separation of daughter cells

5. Arrangements of Cocci: Diplococci
Figure 11.6a

6. Arrangements of Cocci: Streptococci
Figure 11.6b

7. Arrangements of Cocci: Tetrads
Figure 11.6c

8. Arrangements of Cocci: Staphylococci
Figure 11.6e

9. Arrangements of Bacilli: Single Bacillus
Figure 11.7a

10. Arrangements of Bacilli: Diplobacilli
Figure 11.7b

11. Arrangements of Bacilli: Streptobacilli
Figure 11.7c

12. Arrangements of Bacilli: V-Shape and Palisade
Figure 11.7d

13. Endospores Produced by Gram-positive bacteria
Bacillus and Clostridium are examples
Each vegetative cell transforms into one endospore
Each endospore germinates to form one vegetative cell
Constitute a defensive strategy against hostile or unfavorable conditions
Endospores are not reproductive structures

14. Modern Prokaryotic Classification
Three domains of Life
Archaea (prokaryote)
Bacteria (prokaryote)
Eukarya (eukaryote)

15. Archaea

16. Features of Archaea Prokaryotes (no membrane bound nucleus)
Lack Peptidoglycan in their cell walls
Genome is circular DNA
Histone proteins are present
Ribosomes are more similar to bacteria than eukaryotes
Many occupy "extreme' environments. Extremophiles
Not known to cause disease in humans or animals

17. Halophiles Inhabit extremely saline habitats
Depend on greater than 9% NaCl to maintain integrity of cell walls
Many contain red or orange pigments; protection from visible and UV light
Extreme Halophiles… require very high salt (not just tolerant)
Most require at least 9 % NaCl
Most require 12-23% NaCl for optimal growth
Almost all can grow at 32% NaCl
Most studied – Halobacterium salinarium

18. Extreme Halophiles Great salt lake Seawater evaporation ponds
African “soda lake” high alkalinity, high salinity
SEM of halophiles

19. Methanogens
Convert carbon dioxide, hydrogen gas, and organic acids to methane gas
Largest group of archaea
Convert organic wastes in pond, lake, and ocean sediments to methane
Some live in colons of animals; are one of primary sources of environmental methane

20. Methanogens CH4 (methane producers) Strict anaerobes
Example genus: Methanococcus

21. Methanogens
Methanogen habitats

22. Hyperthermophiles Most are obligate anaerobes
Most require S as part of their metabolic scheme
Example Genera:
Sulfolobus Thermococcus Pyrolobus
Hyperthermophiles – require temperatures over 80ºC
Heat stable biomolecules

23. Hyperthermophile Habitats

24. Bacterial groups

25. Phototrophic Bacteria
Photoautotrophs
Five groups … (often grouped by color)
Blue-green bacteria (cyanobacteria)
Chlorophyll a (oxygenic photosynthesis)
Green sulfur bacteria bacteriochlorophyll
Green nonsulfur bacteria “
Purple sulfur bacteria “
Purple nonsulfur bacteria “

26. Phototrophic Bacteria
Table 11.1

27. Low G + C Gram-Positive Bacteria
Clostridia
Mycoplasma
Bacillus
Listeria
Lactobacillus
Streptococcus
Staphylococcus

28. High G + C Gram-Positive Bacteria
Includes rod-shaped cells and filamentous bacteria
Corynebacterium
Mycobacterium
Actinomycetes
Actinomyces
Nocardia
Streptomyces

29. Actinomycetes
Figure 11.17

30. Gram-Negative Proteobacteria
Largest and most diverse group of bacteria
More diseases are caused by this group than any other.
Five distinct classes
Alphaproteobacteria
Betaproteobacteria
Gammaproteobacteria
Deltaproteobacteria
Epsilonproteobacteria

31. Alphaproteobacteria Nitrogen fixers Nitrifying bacteria
Azospirillum
Rhizobium
Nitrifying bacteria
Nitrobacter
Purple nonsulfur phototrophs
Pathogenic alphaproteobacteria
Rickettsia
Brucella
Ehrlichia
Caulobacter

32. Betaproteobacteria Pathogenic betaproteobacteria
Neisseria
Bordetella
Nonpathogenic betaproteobacteria
Thiobacillus
Spirillum

33. Gammaproteobacteria Purple sulfur bacteria Intracellular pathogens
Legionella
Coxiella
Methane oxidizers
Facultative anaerobes
Family Enterobacteriaceae
Pseudomonads
Pseudomonas
Azotobacter
Azomonas

34. Deltaproteobacteria
Bdellovibrio
Myxobacteria

35. Epsilonproteobacteria
Campylobacter
Helicobacter

36. Other Gram-Negative Bacteria
Chlamydias
Chlamydia
Spirochetes
Treponema
Borrelia
Bacteroids
Bacteroides