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Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Chapter 11

The Prokaryotes: Domains Bacteria and Archaea

Part 2

Page 2: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 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)

Page 3: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

The Nonproteobacteria Gram-Negative Bacteria

Page 4: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Photosynthetic Bacteria

Page 5: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 6: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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)

Cyanobacteria

Page 7: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Cyanobacteria

Figure 11.12a-c

Page 8: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• Anoxygenic photosynthesis (does not produce O2)

– carry out photosynthesis to make carbohydrates – Possess chlorophyll

Purple and Green Photosynthetic Bacteria

2H2S + CO2

light(CH2O) + H2O + 2S0

2H2O + CO2

light(CH2O) + H2O + O2

Oxygenic

Anoxygenic (purple sulfur and green sulfur bacteria)

Page 9: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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. trachomatisTrachoma, STD, urethritis

• C. pneumoniae Mild form of pneumoniae

• C. psittaci Causes psittacosis (ornithosis)

Phylum Chlamydiae

Page 10: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

In Bergey's Manual, Volume 5

Figure 11.22a

Page 11: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

In Bergey's Manual, Volume 5

Figure 11.22b

Page 12: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Phylum Spirochaetes

Figure 11.23

• 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)

Page 13: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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

Phylum Bacteroidetes

Page 14: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• Often pleomorphic, may be spindle-shaped– Fusobacterium:

found in mouth (gingival crevice); may be involved in dental diseases

Phylum Fusobacteria

Figure 11.24

Page 15: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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)

Page 16: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• Low G + C

• Gram-positive

Phylum Firmicutes

Page 17: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Order Clostridiales

Figure 11.14 & 15

• Clostridium– 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

Page 18: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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

Order Bacillales

Figure 11.16b

Page 19: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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

Order Bacillales

Figure 1.17

Page 20: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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

Order Lactobacillales

Page 21: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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)

Page 22: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 23: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• Wall-less and highly pleomorphic

• Very small (0.1 - 0.25 µm)

• Degenerative evolution– M. pneumoniae:

common form of mild pneumonia

– Spiroplasma: plant pathogens and common parasites of plant-feeding insects

Order Mycoplasmatales

Figure 11.19a, b

Page 24: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Actinobacteria

• High G + C

• Gram-positive; highly pleomorphic; tend to be filamentous; very common inhabitants in soil

Page 25: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 26: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 27: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 28: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 29: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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

Phylum Actinobacteria

Figure 11.20b

Page 30: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• Bacteria size range– Thiomargarita

(750 µm) to nanobacteria (0.02 µm) in rocks

Microbial Diversity

Figure 11.26

Page 31: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

• 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

Microbial Diversity

Page 32: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 33: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 34: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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)

Page 35: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Domain Bacteria3) 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

Page 36: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Domain Bacteria

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)

Page 37: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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)

Page 38: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Domain Bacteria

• Gram-positive bacteria– 2 groups based on G + C ratio1) 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

Page 39: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Domain Bacteria

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)

Page 40: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 41: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 42: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

Domain Archaea

– 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)

Page 43: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 44: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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

Page 45: Chapter 11 The Prokaryotes: Domains Bacteria and Archaea Part 2

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