1. 149 Chapter 11 Characterizing and Classifying Prokaryotes
General Characteristics of Prokaryotic Organisms:
No nuclear membrane and cellular organelles
Morphology of Prokaryotic Cells:
There general shapes:
Coccus (spherical):
Micrococcus Diplococcus
Streptococcus Staphylococcus
Tetrad Sarcina

2. Arrangements of cocci
Figure 11.6

3. Arrangements of bacilli
Figure 11.7

4. Typical prokaryotic morphologies
Figure 11.1

5. 149
Bacillus (rod-shaped):
Coccobacillus
Fusiform bacillus
Club-shaped bacillus
Bacillus with rounded ends
Bacillus with square ends
Diplobacillus
Streptobacillus
Filamentous bacillus

6. 149
Graham-Smith divided the bacilli into four
groups:
a. Loop forming group
b. Folding group
c. Snapping group
d. Slipping group

7. Spirillum (spiral-shaped):
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Spirillum (spiral-shaped):
a. Vibrio b. Spirillum
c. Borrelia d. Treponema
e. Leptospira
Borrelia, treponema and leptospira are called spirochetes. They are flexible and have no external flagella. Vibrio and spirillum are rigid and have external flagella.

8. 150
Reproduction of Prokaryotic Cells:
1. Binary fission
2. Asexual spores
3. Fragmentation
4. Budding
5. Viviparity: gives birth to youngs
Epulopiscium in surgeonfish

9. Binary fission
Figure 11.2

10. Budding
Figure 11.5

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Sporulation (sporogenesis)
Endospores:
Central spores
Subterminal spores
Terminal spores
High contents of calcium ions, and dipicolinic acid (DPA)--- heat resistance

12. Locations of endospores
Figure 11.8

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Survey of Archaea:
Archaea differ from bacteria in:
Not having peptidoglycan in their cell walls.
Having branched hydrocarbon chains in the membrane lipids.
Having methionine instead of N-formylmethionine as the initial amino acid in protein synthesis.

14. Archaea
Figure 11.10

15. 151 Archaea are classified in three phyla based on rRNA: Crenarchaeota
Euryarchaeota
Korarchaeota: No members have been found.
Archaea reproduce by binary fission, budding or fragmentation. They can be cocci, bacilli, spirals or pleomorphic. Their cell walls contain no peptidoglycan. None cause human diseases. They live in unusual habitats.

16.
Thermophiles:
over 80oC. Geogemma and Pyrodictium live in acidic hot springs and volcanic habitats.
Halophiles:
over 9% NaCl; optimal range is 17-23%
Halobacterium salinarium is a photoheterotroph.

17. Some hyperthermophilic archaea live in hot springs
Figure 11.11

18. The habitat of halophiles: Highly saline water
Figure 11.12

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Methanogens:
convert C02 and H2 into methane gas (CH4); include mesophiles and thermophiles. Methanopyrus grows in 110oC around hydrothermal vents.

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Survey of Bacteria:
The 2nd edition of Bergey’s Manual classifies bacteria based on differences in 16S rRNA.
Deeply Branching and Phototrophic Bacteria:
autotrophic and anaerobic, living in hot, acidic habitats.
Aquifex: G-, hyperthermophilic, anaerobic and
chemoautotrophic.
Deinococcus: G-, unique lipids in its membranes
and high level of manganese; resistant
to radiation.

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Phototrophic Bacteria:
Blue-green bacteria (cyanobacteria)
Green sulfur bacteria
Green nonsulfur bacteria
Purple sulfur bacteria
Purple nonsulfur bacteria

22. Examples of cyanobacteria with different growth habits
Figure 11.13

23. Deposits of sulfur within purple sulfur bacteria
Figure 11.14

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Green and Purple Phototrophic Bacteria:
They differ from plants, algae and cyanobacteria in:
1. using bacteriochlorophylls instead of
chlorophyll a.
2. anoxygenic

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Low G+C Gram-Positive Bacteria:
Clostridia:
Clostridium tetani (tetanus)
Cl. botulinum (botulism)
Cl. perfringens (gangrene)
Mycoplasmas:
M. pneumoniae (atypical pneumonia)

26. Distinctive “fried egg” appearance of Mycoplasma colonies
Figure 11.15

27.
Other Low G+C Bacilli and Cocci:
Bacillus:
B. thuringiensis, B. polymyxa (polymyxin), B. licheniformis (bacitracin), B. anthracis (anthrax)
Listeria:
L. monocytogenes (meningitis and bacteremia)

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Streptococcus and Enterococcus:
strept throat, scarlet fever, impetigo, fetal meningitis, wound infections, pneumonia, disease of inner ear, skin, blood and kidneys. Flesh-eating steptococci.
Staphylococcus:
S. aureus: bacteremia, pneumonia, wound infections, food poisoning, toxic shock syndrome, etc.

29. 154 High G+C Gram-Positive Bacteria:
Many members of Phylum Actinobacteria with greater than 50% G+C are human pathogens.
Corynebacterium:
C. diphtheriae (diphtheria)
Mycobacterium:
M. tuberculosis (TB) and M. leprae (leprosy)
Cell walls contain mycolic acids.

30.
Actinomycetes: filamentous, produce spores at the ends of their filaments. There are three important genera:
Actinomyces:
A. israelii causes actinomycosis (tissue-
destroying)
Nocardia:
N. asteroides causes pneumonia, cutaneous infections may lead to mycetoma, and draining sores.
Streptomyces:
Members of this genus are soil bacteria, give soil
its musty smell, produce antibiotics.

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Gram-Negative Proteobacteria: 16S rRNA
There are five distinct classes:
Alphaproteobacteria:
Nitrogen fixers: Azospirillum, Rhizobium
Nitrifying bacteria: Nitrobacter converts ammonia (NH3) and ammonium (NH4) into nitrate (NO3-) in a process called nitrification.

32. 155 Purple Nonsulfur Phototrophs: Pathogenic Alphaproteobacteria:
Rickettsia prowazakii (epidemic typhus)
R. rickettsii (Rocky mountain spotted fever)
Brucella abortus (brucellosis)
Other Alphaproteobacteria:
Acetobacter and Gluconobacter produce acetic acid (vinegar)
Caulobacter: in nutrient-poor habitats
Agrobacterium tumefaciens (crown gall)

33. 156
Betaproteobacteria: G-, live in low levels of nutrients.
Nitrosomonas oxidizes nitrite to nitrate.
Pathogenic Betaproteobacteria:
Neisseria gonorrhoeae (gonorrhea)
Bordetalla pertussis (pertussis)
Burkholderia: colonizes the respiratory tract of patients with cystic fibrosis.

34. 156
Other Betaproteobacteria:
Thiobacillus: oxidizes hydrogen silfide or sulfur to sulfate.
Zoogloea forms compact flocs that settle in sweage treatment tank.
Sphaerotilus forms loose flocs that do not settle.

35. 156
Gammaproteobacteria:
Purple sulfur bacteria:
obligate anaerobes, oxidize hydrogen sulfide to sulfur.
Intracellular Pathogens:
Legionella pneumophila (Legionnaires’
disease)
Coxiella burnetii (Q fever)

36. 156
Methane Oxidizers:
Methylococcus: G+, uses (digests) methane gas carbon and energy source, inhabits anaerobic environments.
Glycolytic Facultative Anaerobes:
G-, facultatively anaerobic rods, break down carbohydrates by glycolysis and pentose phosphate pathway.

37. 157
Deltaprotobacteria:
Desulfovibrio: releases hydrogen sulfide during anaerobic respiration, corrodes iron pipes.
Bdellovibrio: G-, non-pathogenic, has an unusual life cycle. It drills through cell wall and stays between the cell wall and the cytoplasmic membrane. It feeds on its host and divides into many smaller cells. Each cell produces a flagellum and swims off from its dead host.

38. 157
Myxobacteria: G-, aerobic, soil-dwelling When nutrients are depleted, they aggregate to form a mound of cells, which differentiate to form a fruiting body. Dormant myxospores are formed within a thick walled sporangium. When the sporangium ruptures, myxospores are released. Myxospores germinate to form vegetative cells again.

39. 157 Epsilonproteobacteria: G- rods, vibrios or spirals
Campylobacter causes blood poisoning and inflammation of the intestine.
Helicobacter pyloris causes ulcers.
Other Gram-Negative Bacteria:
Chlamydias: lack peptidoglycan, obligate intracellular parasites causing neonatal blindness, pneumonia and lymphogranuloma venereum.

40. 157
Life cycle of Chlamydias:
The infectious form, called elementary body, is taken into a phagocyte by phagocytosis. The parasite undergoes repeated binary fissions to form many noninfectious forms called reticulate bodies, which transform into elementary bodies and are released from the host cell.

41. 158 Spirochetes: move by means of periplasmic flagella
Treponema pallidum (syphilis)
Borrelia burgdorferi (Lyme disease)
Borrelia recurrentis (relapsing fever)
Bacteroids: G-, obligate anaerobes, inhabit in intestines, can cause abdominal, pelvic, blood and other infections.
Cytophaga: aquatic, gliding, rod-shaped aerobe with pointed ends, degrades cellulose, damages wooden boats and piers.