Living Large in Microscopic Nooks

1
Living Large in Microscopic Nooks

• Katrina Edwards
• Associate Scientist
• Marine Chemistry Geochemistry
• Woods Hole Oceanographic Institution
• Oceanus 2004 42,2
• Presented By Kristina Harris

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Deep Sea Microbes

• In the 1970s deep sea hydrothermal vents were
  discovered
• Dissolved hydrogen, hydrogen sulfide and methane
  provide energy for microbes that live in these
  vent areas

• In 2000, scientists set out to find bacteria that
  used solid minerals as their only source of energy

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Methods

• Alvin was used to place microbe free samples of
  natural seafloor rock onto t he seafloor
• Alvin is capable of reaching depths of 13,000ft
  and holds a three man crew
• Rocks were retrieved by Alvin and studied after
  two months on the sea floor

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What Scientists found

• Rusty-orange coating on the surface of the rocks
• abundant pits and pores less than 20 microns
  (0.0004 inches) deep and wide
• corkscrew-shaped stalks made of iron oxide (rust)

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The Process

• Microbes oxidize iron in the rocks
• The rocks are then chemically altered
• Microbes steal electrons from iron atoms in the
  rocks
• Change from ferrous (Fe2) to ferric (FE3)
• With the energy produced by this chemical
  reaction, they convert CO2 (from seawater) into
  organic matter

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The Results

• Oxygen loving microbes move into pits where they
  consume the avaliable oxygen
• Seawater doesnt flow into these areas so the
  oxygen is not replenished
• This creates an ideal environment for the iron
  loving microbes

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The Results

• As a by-product of the iron oxidizing process,
  iron-oxide stalks are produced
• The stalks accumulate and maintain the low oxygen
  requirements of these microbes

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The Results

• The pits contain just enough oxygen from the
  seawater for the microbes to respire
• Too much oxygen would oxidize all the iron in the
  rocks

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What Now?

• These microbes are very difficult to culture in
  the lab
• Various species have been identified
• Scientists are currently working on revealing the
  microbes metabolic pathways and biochemical
  machinery
• Genes and the enzymes these microbes produce are
  also being investigated

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What Now?

• FeMO established to study microbes where they
  are diverse and prolific
• FeMO Iron Oxidizing Microbe Observatory
• Located at a submerged volcano named Loihi 25
  miles off the island of Hawaii

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• Iron oxide is visible on the seafloor on Loihi
  Seamount, an underwater active volcano
• Whats next?

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Geomicrobiology

• A new area of study
• look for unknown microbes that play major roles
  in cycling chemicals
• rocks and minerals
• planets and moon with iron rich rocks or soil
• University of Wisconsin

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New Questions

• Analyzed assortment of holes drilled by the Ocean
  Drilling Program into volcanic rock on both side
  of the mid-ocean ridge mountain chain
• older rocks depleted of Fe2 and full of Fe3
• millions of square miles of habitat

• Do these microbes have an influence on the
  chemistry of the ocean?
• How have they altered the earths crust?
• Were they pioneering life forms?
• Does this large scale drawdown of CO2 from
  seawater help the ocean absorb carbon dioxide