1. The Prokaryotes: Domains Bacteria and Archaea Part 2
Chapter 11
The Prokaryotes: Domains Bacteria and Archaea
Part 2

2. The Nonproteobacteria Gram-Negative Bacteria
Not closely related to the gram-negative proteobacteria
Several physiological and morphologically distinctive photosynthesizing bacteria
Phyla Cyanobacteria, Chlorobi (green sulfur bacteria) & Choloroflexi (green nonsulfur bacteria)

3. The Nonproteobacteria Gram-Negative Bacteria

4. Photosynthetic Bacteria

5. Photosynthetic Bacteria
Phyla Cyanobacteria, Chlorobi, Chloroflexi, photosynthetic purple sulfur bacteria (-proteobacteria), and purple nonsulfur bacteria (-proteobacteria)
Photoautotrophs and chemoheterotrophs
Photosynthetic purple and green sulfur bacteria are generally anaerobic and usually found in deep sediments of lakes and ponds

6. Cyanobacteria Oxygenic (oxygen-producing) photosynthetic bacteria
Produce O2 from H2O using light energy
Characteristic blue-green (cyan) pigmentation
Gliding motility or gas vacuoles
Fix nitrogen (into ammonium) from atmosphere in specialized cells called heterocysts
Morphologically varied (Unicellular to colonial form)

7. Cyanobacteria
Figure 11.12a-c

8. Purple and Green Photosynthetic Bacteria
Anoxygenic photosynthesis (does not produce O2)
carry out photosynthesis to make carbohydrates
Possess chlorophyll
2H2S + CO2
light
(CH2O) + H2O + 2S0
2H2O + CO2
(CH2O) + H2O + O2
Oxygenic
Anoxygenic (purple sulfur and green sulfur bacteria)

9. Phylum Chlamydiae Do not contain peptidoglycan in cell walls
Chlamydia: intracellular parasite; a unique developmental cycle (elementary body is the infective agent); gram-negative coccoid
Transmitted via interpersonal contact or by airborne respiratory routes
C. trachomatis Trachoma, STD, urethritis
C. pneumoniae Mild form of pneumoniae
C. psittaci Causes psittacosis (ornithosis)

10. In Bergey's Manual, Volume 5
Figure 11.22a

11. In Bergey's Manual, Volume 5
Figure 11.22b

12. Phylum Spirochaetes
Coiled morphology; outer sheath; axial filaments (endoflagella) for motility
many are found in oral cavity
Borrelia Relapsing fever and Lyme disease
Leptospira leptospirosis
Treponema syphilis (T. pallidum)
Figure 11.23

13. Phylum Bacteroidetes Anaerobic Bacteria
Bacteroides: nonmotile; in mouth (gingival crevice) and large intestine; also recovered frequently from deep tissue infections
Cytophaga: degrade cellulose and chitin in soil; gliding motility

14. Phylum Fusobacteria Often pleomorphic, may be spindle-shaped
Fusobacterium: found in mouth (gingival crevice); may be involved in dental diseases
Figure 11.24

15. Gram-Positive Bacteria
Two groups:
high G + C ratios (above 50%)
e.g. Phylum Actinobacteria (mycobacteria, corynebacteria,and actinomycetes)
low G + C ratios (below 50%)
e.g. Phylum Firmicutes (common soil bacteria, lactic acid producing bacteria, and several human pathogens)

16. Phylum Firmicutes
Low G + C
Gram-positive

17. Order Clostridiales Clostridium Epulopiscium Form endospores
Obligate anaerobes
C. botulinum Botulism
C. tetani Tetanus
C. perfringens Gas gangrene Food diarrhea
C. difficile Severe diarrhea
Epulopiscium
Giant prokaryote; symbiotic in the gut of surgeonfish
Figure & 15

18. Order Bacillales Important genera of gram-positive rods and cocci
Bacillus
Rod-shaped bacteria that form endospores
Common in soils
B. anthracis: Anthrax
B. thuringiensis: Microbial insect pathogen
B. cereus: Occasional food poisoning
Figure 11.16b

19. Order Bacillales Staphylococcus Cocci in clusters
S. aureus: facultative anaerobes; can tolerate high osmotic pressure and low moisture; produce many toxins (e.g. enterotoxin); toxic shock syndrome, food poisoning
Figure 1.17

20. Order Lactobacillales
Generally aerotolerant anaerobes, lack an electron-transport chain
Lactobacillus
produce lactic acid (industrial and commercial application); found in vagina, intestinal tract, and oral cavity
Enterococcus
facultative anaerobes; found in GI tract, vagina, and oral cavity; leading cause of nosocomial infection

21. Order Lactobacillales
E. faecalis & E. faecium: infect surgical wounds & urinary tract
Listeria: facultative anaerobes
L. monocytogenes: contaminate food (dairy products); can grow in refrigeration temperature
Streptococcus
Usually cocci in chains; human pathogens
Have hemolytic activity (alpha hemolysis, beta hemolysis, and no hemolysis)

22. Order Lactobacillales
S. pyogenes: scarlet fever, pharyngitis, impetigo, and rheumatic fever
S. mutans: dental carries
S. pneumoniae: most common cause of pneumonia
Figure 11.18

23. Order Mycoplasmatales
Wall-less and highly pleomorphic
Very small ( µm)
Degenerative evolution
M. pneumoniae: common form of mild pneumonia
Spiroplasma: plant pathogens and common parasites of plant-feeding insects
Figure 11.19a, b

24. Actinobacteria High G + C
Gram-positive; highly pleomorphic; tend to be filamentous; very common inhabitants in soil

25. Phylum Actinobacteria
Mycobacterium
Aerobic, acid-fast (contains mycolic acids which forms waxy, water resistant layer in cell wall); slow grower (may take weeks for visible colonies to appear)
Found in soil and water; occasional pathogens
Human pathogens
M. tuberculosis Tuberculosis
M. leprae Leprosy

26. Phylum Actinobacteria
Nocardia
Aerobic; filamentous morphology
Reproduction by forming rudimentary filaments which fragment into short rods
Cell wall resemble mycobacteria; often acid-fast
N. asteroides Mycetoma and occasionally cause a chronic, difficult-to-treat pulmonary infection

27. Phylum Actinobacteria
Corynebacterium
Tend to be pleomorphic; morphology varies with the age of the cells
C. diphtheriae Diphtheria
Propionibacterium
Form propionic acid; fermentation of Swiss cheese
P. acnes Common on human skin, cause acne
Frankia
Form nitrogen-fixing nodule in alder tree roots

28. Phylum Actinobacteria
Gardenella
Gram-variable; highly pleomorphic
Cause of one of the most common forms of vaginitis
Actinomyces
Facultative anaerobe; filamentous morphology
Found in the mouth and throat of humans and animals
A. israelii actinomycosis

29. Phylum Actinobacteria
Streptomyces
One of the most commonly isolated bacteria from soil; responsible for the musty odor of soil
Strict aerobes; filamentous bacteria
Produce most of our commercial antibiotics
Figure 11.20b

30. Microbial Diversity Bacteria size range
Thiomargarita (750 µm) to nanobacteria (0.02 µm) in rocks
Figure 11.26

31. Microbial Diversity
PCR indicates up to 10,000 bacteria/gm of soil. Many bacteria have not been identified or characterized because they:
Haven't been able to culture (need to develop special media/nutrients and cultivation condition)
Are part of complex food chains requiring the products of other bacteria
Need to be cultured to understand their metabolism and ecological role

32. Chapter Review
Prokaryotic organisms are classified into 2 domains: Archaea & Bacteria based on rRNA sequences
Each domain is further subdivided into phylum, class, order, family, genus, and species
Domain Bacteria
Relatively few species cause disease in humans, animals, plants or any other organisms
Essential part of life on Earth

33. Domain Bacteria Phylum: Proteobacteria (gram-negative bacteria)
1) Alpha- (α-) proteobacteria
Includes most of the proteobacteria that are capable of growth at very low levels of nutrients; nitrogen –fixing bacteria & several plant & human pathogens
Some bacteria with unusual morphology such as prosthecae
Prosthecae: a stalk or bud protruding from a prokaryotic cell

34. Domain Bacteria 2) Beta- (-) proteobacteria
Often use nutrient substances that diffuse away from areas of anaerobic decomposition of organic matter
Considerable overlap between the α- & -proteobacteria, especially among the nitrifying bacteria; some human pathogens in this group
Spirillum helical shaped bacteria, but use flagella for motility (not axial filament)

35. Domain Bacteria 3) Gamma- (-) proteobacteria
Constitute the largest subgroup of proteobacteria; many are human & plant pathogens (e.g. Order Pseudomonadales, Legionellales, Vibrionales, Enterobacteriales, & Pasteurellales)
4) Delta (-) proteobacteria
Include some bacteria that are predators of other bacteria and important contributors to the sulfur cycle (e.g. Bdellovibrio, Desulfovibrio, and Myxococcus)
Myxococcus form fruiting bodies under low nutrients condition

36. Domain Bacteria Gram-negative Nonproteobacteria
5) Epsilon- (-) proteobacteria
Slender gram-negative rods that are helical or vibrioid (e.g. Campylobacter & Helicobacter)
Vibrioid: helical bacteria that do not have a complete turn
Gram-negative Nonproteobacteria
Include several photosynthetic bacteria: Phyla cyanobacteria, green sulfur bacteria, & green nonsulfur bacteria (Table 11.2)

37. Domain Bacteria
Purple sulfur (α-proteobacteria) & purple nonsulfur (-proteobacteria) also included in this section
Cyanobacteria carry out oxygenic (oxygen-producing) photosynthesis and fix nitrogen gas (in specialized cell called heterocyst) from the atmosphere into ammonium
Green & purple photosynthetic bacteria carry out anoxygenic photosynthesis (generally anaerobic)

38. Domain Bacteria Gram-positive bacteria 2 groups based on G + C ratio
1) Firmicutes (low G + C ratio)
Includes important endospore forming bacteria (e.g. Bacillus & Clostridium), medically important bacteria (e.g. Staphylococcus, Enterococcus, & Streptococcus), industrially important bacteria (e.g. Lactobacillus), and wall-less Mycoplasma

39. Domain Bacteria Assorted Phyla 2) Actinobacteria (high G + C ratio)
Highly pleomorphic, but tend to be fimalentous
Common inhabitants in soil
e.g. acid-fast group (e.g. Mycobacterium & Nocardia), and antibiotic producing Streptomyces.
Assorted Phyla
Chlamydiae: no peptidoglycan in cell wall; intracellular parasite (human pathogen); has unique developmental cycle (elementary body = infectious)

40. Domain Bacteria
Spirochaetes: coiled morphology; motility by axial filament; many found in human oral cavity & in environment; some human pathogens
Bacterioidetes: several genera of anaerobic bacteria
Fusobacteria: anaerobic bacteria, spindle-shaped (often pleomorphic); can cause dental diseases

41. Domain Archaea Cell wall lacks peptidoglycan; a few lack cell wall
Frequent inhabitants of exceptional extreme environment (heat, cold, acidity, & pressure)
3 major groups:
Extreme halophiles: survive in very high concentrations of salt; found in Great Salt Lake, solar evaporating ponds, salinas, & Dead Sea

42. Domain Archaea Microbial Diversity
Extreme thermophiles: thrive in high temperature (above 70 oC) or sulfur rich environment; found in acidic, sulfur rich hot springs or deep ocean hydrothermal vents
Methanogens: obligately anaerobic methane producing bacteria; found in human intestines and used in sewage-treatment processes
Microbial Diversity
Various sizes: nanobacteria (0.02 – 0.03 μm) to giant bacteria (750 μm)

43. Microbial Diversity
Many bacteria in the environment have not been identified or characterized due to:
Lack of culture method
Some bacteria are part of complex food chains and can only grow in the presence other microbes that provide specific growth requirements
PCR can be used to reveal the presence of bacteria that cannot be cultured in the laboratory

44. Chapter Review Know these terms: prosthecae, vibrioid, and oxygenic
Know different groups of proteobacteria (and some examples) given in the chapter review section
Know the names of different photosynthesizing bacteria and their mode of photosynthesis

45. Chapter Review
Know characteristics of 2 groups of gram-positive bacteria and some of the examples listed in the chapter review
Know characteristics of Arhaea, and its 3 major groups (characteristics and where they are found) given in the chapter review
Know why many bacteria have not been classified and identified (2 main reasons) & use of PCR to detect them without culturing them