Chapter 11 B&A Diversity Flashcards Preview

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Flashcards in Chapter 11 B&A Diversity Deck (19):

Metabolic Diversity

- Anaerobic chemotrophs
- Anoxygenic phototrophs
- Aerobic chemoorganotrophs
- Oxygenic phototrophs
- Aerobic chemolithotrophs


Anaerobic Chemotrophs

▪ Anaerobic Chemolithotrophs
▪ oxidize reduced inorganic chemicals to obtain energy, e.g.
▪ Use alternative electron acceptor e.g CO2, sulfur
▪ Example; methanogens

▪ Anaerobic Chemoorganotrophs -respiration
▪ oxidize organic compounds (glucose) to obtain energy
▪ use sulfur, sulfate as electron acceptor
▪ Example: sulfur and sulfate-reducing bacteria

▪ Anaerobic Chemoorganotrophs - fermentation
▪ generate ATP via substrate level phosphorylation
▪ Example - clostridium


Anoxygenic Phototrophs

• Use hydrogen sulfide or organic compounds (not water) to make NADPH; do not generate O2

• Use unique bacteriochlorophyll

Purple sulfur bacteria bacteria use H2S, H2, pyruvate representative

Purple Non-sulfur bacteria use organic molecules representative

Green bacteria -Green sulfur bacteria Representatives


Oxygenic Phototrophs

• Many convert N2 to ammonia: nitrogen fixation
• Earliest oxygenic phototrophs
• Use water as source of electrons for reducing power
• Harvest sunlight to convert CO2 into organic compounds


Aerobic Chemolithotrophs

▪ Gain energy by oxidizing reduced inorganic chemicals using oxygen
S(inorganic energy source) + O2 —>

Sulfur-Oxidizing Bacteria derive energy from oxidation sulfur, sulfur compounds can be filamentous and unicellular

Nitrifiers - oxidize inorganic nitrogen compounds for energy -ammonium oxidizers (Nitrosomonas) and nitrite oxidizers (Nitrobacter)

Hydrogen- Oxidizing Bacteria


Aerobic Chemoorganotrophs

▪ Oxidize organic compounds for energy using oxygen
(Organic compound) + O2 —> CO2 + H2O


Bacteria That Form a Resting Stage

Cyst formers Azotobacter
Fruit body formers Myxobacteria


Sheathed bacteria

• Form chains of cells within tube
• Sheaths protect, help bacteria attach to solid objects
• Often seen streaming from rocks in water polluted by nutrient-rich effluents; may clog pipes
• Include Gram-negative rods Sphaerotilus, Leptothrix
• Motile swarmer cells exit open end of sheath, move to new surface, attach


Prosthecate bacteria

• Have extensions of cytoplasm and cell wall called prosthecae: provide increased surface area for nutrient absorption, some allow attachment
• Caulobacter serve as model
• Hypomicrobium similar to Caulobacter
• Have distinct method of reproduction, budding


Bacteria That Derive Nutrients from Other Organisms

• Bdellovibrio: highly motile Gram-negative curved rods
• Prey on E. coli and other Gram-negatives
• Strikes forcefully; prey propelled short distance
• Parasite attaches, rotates, secretes digestive enzymes; forms hole in cell wall of prey

Bioluminescent bacteria: Photobacterium, Vibrio
• Symbiotic relationships with certain fish, squid
• Help with camouflage, confuse predators and prey • Bioluminescence under control of quorum sensing • Gram-negative rods (Vibrio are curved rods)
• Facultative anaerobes


Bacteria That Move by Unusual Mechanisms

▪️Spirochetes: group of Gram-negatives with spiral shape
• Flexible cell wall
• Endoflagella or axial filament contained within periplasm allows corkscrew-like motion
• Able to move through viscous environments like mud

▪️Magnetotactic bacteria contain magnetic crystals that align cells with Earth’s magnetic fields
• Allows movement up or down in water or sediments
• Likely allows location of their required microaerophilic habitats


Bacteria That Form Storage Granules

• Spirillum: Gram-negative spiral-shaped microaerophilic bacteria; phosphate as volutin granules: Metachromatic granules

• Sulfur-Oxidizing, Nitrate-Reducing Marine Bacteria
• Some store sulfur (energy source) and nitrate (terminal electron acceptor) not found in same environment


Bacteria That Inhabit the Skin

• Skin typically dry, salty; inhospitable to many microbes
• Staphylococcus are Gram-positive cocci
• Facultative anaerobes; catalase-positive
• Most harmless ( for example, S. epidermidis)


Bacteria That Inhabit Mucous Membranes

• Bacteroides: Gram-negative rods and coccobacilli
- Small; strict anaerobes that inhabit mouth, intestinal tract, genital tract of humans and other animals

• Bifidobacterium: Gram-positive irregular rods
- Anaerobes; reside primarily in intestinal tract of humans and other animals
- Predominant members of intestinal microbiota of breast- fed infants; thought to exclude pathogens

• Bordetella: small, Gram-negative coccobacilli, B pertussis (whooping cough)

• Campylobacter and Helicobacter: microaerophilic Gram- negative curved rods
- C. jejuni causes diarrhea in humans
- H. pylori causes ulcers, produces urease, breakdown urea to ammonia to neutralize local pH
• Haemophilus: Gram-negative coccobacilli
-“Blood-loving”: require hematin and/or NAD blood

• Many common microbiota of respiratory tract
• H. influenzae causes ear infections, respiratory infections, meningitis
• H. ducreyi causes STI chancroid

• Mycoplasma: lack cell wall, gives flexibility
- M. pneumoniae medically important; antibiotics that target peptidoglycan synthesis not effective
- Colony growth produces characteristic “fried egg” appearance


Obligate Intracellular Parasites

• Cannot reproduce outside a host cell:
• Multiple bacterial examples; all are tiny Gram-negative rods or coccobacilli

▪️Rickettsia, Orientia, Ehrlichia: include species responsible for several serious arthropod-transmitted human diseases

▪️Coxiella: C. burnetii is only characterized species
• Can survive outside host cell as spore-like structures called small-cell variants (SCVs) formed during intracellular growth
• Not as resistant as endospores to heat, disinfectants
• C. burnetii causes Q fever; most often acquired by inhaling bacteria shed from infected animals


Obligate Intracellular Parasites (continued...)

▪Chlamydia, Chlamydophila: transmitted person to person; cell wall lacks peptidoglycan
🔸 Inside host initially as noninfectious reticulate bodies
• Reproduce by binary fission
🔸 Later, differentiate into dense-appearing infectious elementary bodies
• Released when cell ruptures
• Chlamydia trachomatis causes eye infections and STI similar to gonorrhea


Characterized Archaea thrive in extremes

• High heat, acidity, alkalinity, salinity


Extreme Halophiles

▪️Salt lakes, soda lakes, brines
• Most can grow in 32% NaCl; require at least 9% NaCl
• Produce pigments; seen as red patches on salted fish, pink blooms in salt water ponds
• Aerobic or facultatively anaerobic chemoheterotrophs


Extreme Thermophiles

• Found near volcanic vents and fissures that release sulfurous gases, other hot vapors
• Others in hydrothermal vents in deep sea, hot springs
• Methane-Generating Hyperthermophiles
• Methanothermus species grow optimally at 84oC, as high as 97C
• Oxidize H2 using CO2 as terminal electron acceptor