Microbial Geochemistry

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Microbial Geochemistry In Hydrothermal Systems
"Follow the Energy"
Jan Amend Earth Planetary Sciences Environmental
Studies Division of Biology and Biomed.
Sci. McDonnell Center for the Space Sciences
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Anammox Anaerobic Ammonia Oxidation
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Anammox Anaerobic Ammonia Oxidation
NH4 NO2- ? N2 2H2O ?Gº -358 kJ/mol
Broda (1977) Thermodynamics to predict Anammox.
(Z. Allgem. Mikrobiol., 17, 491-493)
Van de Graaf et al. (1995) -- Anammox is
biologically mediated. (AEM, 61, 1246-1251)
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Outline Energy calculations Anabolic
processes Catabolic processes Vulcano (Italy)
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Energy Calculations What is the definition of
pH? pH -log aH aH mH ?H What is
the definition of neutral pH? aH aOH- (H2O
H OH-) What is the value of neutral
pH? log K -14 (pH 7) log K
-12.26 (pH 6.13) log K -11.28 (pH
5.64)
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?Gr ?Grº RT ln Qr
?Grº S ?i ?Giº
?Giº is a function of T, P
CH4 SO42- ? HCO3- HS- H2O
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?Gr ?Grº RT ln Qr
?Grº S ?i ?Giº
?Giº is a function of T, P
CH4 SO42- ? HCO3- HS- H2O ?Gº -33.2
kJ/mol (at 25 C) ?Gº -42.5 kJ/mol (at 100 C)
Qr ? ai? ai mi ?i QAOM
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?Gr ?Grº RT ln Qr
?Grº S ?i ?Giº
?Giº is a function of T, P
CH4 SO42- ? HCO3- HS- H2O ?Gº -33.2
kJ/mol (at 25 C) ?Gº -42.5 kJ/mol (at 100 C)
Qr ? ai? ai mi ?i QAOM
Vulcano
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Dissimilation -- Assimilation
CH4
CO2 H2
CH2O
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Cell Building Blocks
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Mixing of Late Hadean Seawater and Vent
Fluid
CO2(atm) 0.2 bar pH 6.5 Na, Cl modern
SW Ca equilib. Calcite Mg equilib.
Magnesite Fe equilib. Siderite SiO2(aq)
equilib. Qtz H2S(aq) equilib. Pyrite H2(atm)
1 mbar Eh -0.3 mV
HCO3- equilib. Calcite pH 9-11 T lt 150 C
(O, H isotopes) Mg equilib. Brucite Ca
based on Lost City Others nominal conc. H2
based on Lost City Eh -0.71 mV
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Amend McCollom (2009) , ACS-Chemical Evolution
II
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Dissimilation -- Assimilation
CH4
CO2 H2
CH2O
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DEEP-SEA HYDROTHERMAL SYSTEMS
Tarasov et al. (2005)
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DEEP-SEA SHALLOW-SEA HYDROTHERMAL SYSTEMS
Tarasov et al. (2005)
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Shallow-Sea Hydrothermal System
Modified from Henley Ellis (1983)

• Working Definition
• lt200 m deep
• Meteoric water component
• Discharge into the photic zone
• Phase separation during or just prior to
  discharge

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Characteristics of Shallow-Sea Hydrothermal
System

• Temperatures lt150 ºC

? Exsolved gas phase (CO2-rich)

• Current (recent)
• volcanic/tectonic
• activity
• -- island arcs
• -- mid-ocean ridges
• -- intraplate volcanism
• -- continental margins

? Photo- and chemosynthetic microbes
? No (few) vent obligate macrofauna
? Large mineral structures are rare
? Readily accessible!!!
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DEEP-SEA SHALLOW-SEA HYDROTHERMAL SYSTEMS
Vulcano, Italy
Ambitle, PNG
Tarasov et al. (2005)
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Type Locality for Hyperthermophiles
Archaeoglobus Ferroglobus Pyrodictium Staphylother
mus Thermococcus Pyrococcus Palaeococcus Thermodis
cus Thermotoga Aquifex

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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
All data in mM, except O2, total aldoses, total
amino acids, and DOC (µM), H2 (ppmv), CO2 (vol)
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
All data in mM, except O2, total aldoses, total
amino acids, and DOC (µM), H2 (ppmv), CO2 (vol)
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Amino Acids Alanine Arginine Aspartic
Acid Glutamic Acid Glycine Histidine Isoleucine Le
ucine Lysine Methionine Phenylalanine Serine Threo
nine Tyrosine Valine
Aldoses Arabinose Xylose Galactose Glucose Mannos
e Carbox. Acids Formate Acetate Propanoate Lacta
te
Carbox. Acids
Amino Acids
DOC
Aldoses
Amend et al. (2003) Geobiology Svensson et al.
(2004) Org. Geochem. Skoog et al. (2007) Org.
Geochem.
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Chemolithoautotrophy (90 Reactions)
Normalized per mole of electrons transferred
Data from Amend et al. (2003) Geobiology, 1, 37-58
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Chemoheterotrophy (120 Reactions)
Normalized per mole of electrons transferred
Data from Svensson et al. (2004) Org. Geochem.,
35, 1001-14 Skoog et al. (2007) Org. Geochem.,
38, 1416-30 Rogers Amend (2006) GCA, 70,
6180-6200
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Tor et al. (2003) Environmental
Microbiology Rusch and Amend (2004) Extremophiles
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Archaea
Rogers (2006) Ph.D. Thesis
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Bacteria
Rogers (2006) Ph.D. Thesis
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
M.kandleri
pOWA133
FZ2bA214
VulcPI226
20a1
C1R025
pJP27
VulcPI113
20c19
VulcPI73
pISA7
pUWA2
pISA9
VulcPI207
VulcPI170
FZ3aA1
pSL4
pSL17
VulcPI156
VulcPI36
?
VulcPI115
ATR021
VulcPI10
FZ2bA211
VulcPI11
VulcPI46
pJP89
pSL123
VulcPI124
VulcPI98
pBA1
T.pendens
SRI370
VulcPI101
T.modestius
V.distributa
V.souniana
T.tenax
P.aerophilum
P.islandicum
A.ambivalens
M.sedula
S.solfataricus
S.azoricus
S.acidocaldarius
P.occultum
P.fumarii
T.maritimus
S.marinus
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S.hydrogenophila
D.mobilis
VulcSW8
VulcSW196
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Study Site Microbes Chemistry Energetics Incubatio
ns Gene Surveys
Conclusions

• Energetics
• ?Gr NOT ?Gr0
• ?Gr is a function of T, P, chemical
  composition
• Anabolism (biomass synthesis) in HT systems
• Relatively cheap energetically
• Described as monomer building (redox vs.
  dehydration)
• Catabolism in HT systems
• Chemosynthesis (redox disequilibria)
• 100s of inorganic reactions
• 100s of organic reactions

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