Geomicrobiology

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Geomicrobiology August 29, 2005 Nutrient
Cycling/Biogeochemistry
Microbial life and nutrient cycling Definitions
nutrient cycling and biogeochemistry Elemental
composition of living organisms Major nutrient
cycles what do cells need? The Redfield
Ratio Ecological Stoichiometry
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Lifes History on Earth
Prokaryote World
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Nutrient Cycling biogeochemical cycling in
which inorganic matter moves through organisms
and the environment Biogeochemical Cycling
movement of chemical elements from organisms to
physical environment to organism termed a
nutrient cycle if the element is essential to life
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Cell Elemental Composition 90 Water Of the
remaining molecules present, the dry weight is
approximately 50 protein 15 carbohydrate
15 nucleic acid 10 lipid 10 miscellaneous
Six elements make up almost the entire
composition of living organisms. These elements
are CHONPS
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Metabolism is based on oxidation-reduction
reactions which changes the valence state of
elements
1. Reduced forms are oxidized to gain energy 2.
Oxidized forms are used as electron acceptors (in
the process they are reduced) 3. Elements
incorporated into biomass are usually in a
reduced state (although carbon in not fully
reduced and hydrogen and phosphorus are major
exceptions to this rule)
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The Redfield Ratio (A.C. Redfield)

• Atomic ratios of carbon, nitrogen, and phosphorus
  are relatively constant in marine phytoplankton
  (106C16N1P)
• Phytoplankton growth and decomposition is given
  by the following equation
• 106CO2 16NO3-1 HPO4-2 122H2O 18H1 ?
  C106H263O110N16P1 138O2
• Photosynthesis and respiration

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Ecological Stoichiometry

• Ecological stoichiometry the balance of
  multiple chemical substances in ecological
  interactions and processes, or the study of this
  balance (energy and materials)
• Ecological Stoichiometry The Biology of Elements
  from Molecules to the Biosphere 2002. Robert W.
  Sterner and James J. Elser Princeton University
  Press

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NITROGEN CYCLE
World oceans/lakes Terrestrial
systems Agriculture Waste water mngmt Aquaria
Nitrosospira
NH4
NO2-
Nitrospira
NO3-
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NITROGEN CYCLE ( MINUS MICROBES)