Metabolism LecturesOutline:

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

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

Betaproteobacteria Gram negative, diplococcal Aerobic Most nonmotile N. gonorrhoeae

– VD N. meningitidis

– Spinal meningitis Other Neisseria spp. are

present in respiratory tract of animals.– Most rarely cause disease.

Cultivate on chocolate-blood agar with 3-10% CO2

www.textbookofbacteriology.net

Pseudomonas species

Gram negative, (Gammaproteobact.) Mostly obligate aerobes

– Some can respire nitrate.

Present in soil, water, plant surfaces Some can degrade pollutants

– TNT for example

Produce secondary metabolites– siderophores or iron binding

molecules

Some produce pigments:– Pyocyanin in P. aeruginosa

Some fluoresce:– P. fluorescence

From: www.bact.wisc.edu/Microtextbook

Sulfate reducing bacteria 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– Seawater

Also abundant in anaerobic environments with lots of decomposing organic matter

www.genomenewsnetwork.org

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:

– S. lactis common dairy organism

Oral Streptococcus– 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

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

NO3−-dependent Fe(II)-oxidizer

(Acidovorax sp. strain BoFeN1)Phototrophic Fe(II)-oxidizer(R. ferrooxidans strain SW2)

O2

Fe2+1 μm

Photos by Professor Andreas Kappler

Fe-mineral coating

2 layers

Phototrophic Fe(II)-oxidizer Chlorobium ferrooxidans strain KoFox(co-culture with Geospirillum strain)

EncrustedGeospirillum strain

KoFox cells

How can they avoid encrustation?