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Metabolism Lectures
Outline:
 Part I: Fermentations (Monday)
 Part II: Respiration (Wednesday)
 Part III: Metabolic Diversity (Friday)
Learning objectives are:
 Learn about anaerobic respiratory metabolisms.
 How can an inorganic compound be use as an energy source.
Bacteria and Archaea
Agrobacterium species
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Alphaproteobacteria
Gram negative rods
Common in soil especially the
root zone of plants
Some are plant pathogens
–
–

A. tumefaciens causes crown
galls or plant tumors
Only if A. tumefaciens has
the Ti (tumor inducing)
plasmid.
Elements of Ti have been
engineered to generate
transgeneic plants using.
Neisseria species


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Betaproteobacteria
Gram negative, diplococcal
Aerobic
Most nonmotile
N. gonorrhoeae
–

N. meningitidis
–

Spinal meningitis
Other Neisseria spp. are
present in respiratory tract of
animals.
–

VD
Most rarely cause disease.
Cultivate on chocolate-blood
agar with 3-10% CO2
www.textbookofbacteriology.net
Pseudomonas species


Gram negative, (Gammaproteobact.)
Mostly obligate aerobes
–


Present in soil, water, plant surfaces
Some can degrade pollutants
–

siderophores or iron binding
molecules
Some produce pigments:
–

TNT for example
Produce secondary metabolites
–

Some can respire nitrate.
Pyocyanin in P. aeruginosa
Some fluoresce:
–
P. fluorescence
From: www.bact.wisc.edu/Microtextbook
Sulfate reducing bacteria
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Deltaproteobacteria
Desulfovibrio speices
Strict anaerobes
Generate energy by respiration
of sulfur compounds
Some can use H2 for energy
Many use lactate, acetate, and/or
ethanol as carbon and energy
sources.
Abundant in anaerobic aquatic
environments where sulfate is
high
–

www.genomenewsnetwork.org
Seawater
Also abundant in anaerobic
environments with lots of
decomposing organic matter
picasaweb.google.com/sd.gibson
Campylobacter jejuni
 Gram -, (Epsilonproteobact.)
 Microaerophile
 Most prevalent food-borne
pathogen in US
– Under cooked poultry, pork,
shellfish
 Prevalence of contamination:
– 90% turkeys
– 32% hogs
– 89% chickens
www.cdc.gov/ncidod/eid/vol5no1
Streptococcus



Gram positive, Firmicutes
Pathogenic and non-pathogenic
kinds
Non-pathogenic:
–

Oral Streptococcus
–
–

S. lactis common dairy organism
S. salivarius and mutans
Grow on sugars in the mouth
Pathogenic:
–
–
–
S. pyogenes: strains with
hemolysins can cause scarlet
fever
S. pneumoniae: strains with
capsules can cause disease.
Some are “flesh eating”
Bacteroides


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Rod shap, Gram Negative
Strict anaerobe
Dominant microbe in human feces
1010 per gram
Purely fermentative organisms
Normally commensal
Most anaerobic infections are
Bacteroides species.
 Big problem in GI tract surgeries
from: microbewiki.kenyon.edu
Pyrococcus “fireballs” furiosus
 Anaerobic, Crenarchaea
 Stetter isolated these from
a solfatara field in Vulcano
Italy (1986).
 Uses proteins, starch,
sugars, maltose as
electron donors for S0
reductions
 Also ferments sugars to H2
and CO2
 Growth temps:
– 70-106˚C
– 100˚C is optimum
www.microbeworld.org
Thiobacillus ferrooxidans
 Gamma proteobacteria
 4 Fe(II) + 4 H+ + O2 −−>
4 Fe(III) + 2 H2O
 Fe(II) is stable at acidic pH
– Does not get oxidized in the
presence of O2
 T. ferrooxidans tolerates:
– pH ~2.5
– It’s an acidiphile
 Can be found in acidic mine
waters.
 Add water to pyrite:
– FeS2 −> Fe(III) + H2SO4
– That’s sulfuric acid
Iron mats made by iron
oxidizing bacteria
Anoxic photosynthetic iron(II) oxidizing bacteria
O2
1 μm
NO3−-dependent Fe(II)-oxidizer
(Acidovorax sp. strain BoFeN1)
Photos by Professor Andreas Kappler
Fe2+
Phototrophic Fe(II)-oxidizer
(R. ferrooxidans strain SW2)
Fe-mineral coating
2 layers
Phototrophic Fe(II)-oxidizer
Chlorobium ferrooxidans strain KoFox
(co-culture with Geospirillum strain)
KoFox cells
How can they
avoid encrustation?
Encrusted
Geospirillum strain