Sulfur metabolizing endosymbiotic bacteria

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Sulfur metabolizing endosymbiotic bacteria

• 20 November 2002

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• Name in Other Languages
• Latin Sulphur
• Czech Síra
• Croatian Sumpor
• French Soufre
• German Schwefel - e
• Italian Solfo
• Norwegian Svovel
• Portuguese Enxôfre
• Russian
• Spanish Azufre
• Swedish Svavel

• Who / Where / When / How
• Discoverer Known to the ancients.
• Discovery Location ?
• Discovery Year known to the ancients
• Name Origin
• Latin sulfur (brimstone).
• Sources
• Found in pure form and in ores like cinnabar,
  galena, sphalerite and stibnite.
• Uses
• Used in matches, gunpowder, fireworks, batteries,
  vulcanization of rubber, medicines, permanent
  wave lotion and pesticides. Also for making
  sulfuric acid (H2SO4).

From http//environmentalchemistry.com/yogi/period
ic/S.html
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Global sulfur cycle
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World ridge system
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Hydrothermal vent formation

• Underlying magma heats seawater draining through
  cracks in seafloor
• Sulfate in seawater converted to sulfide in
  anoxic conditions, more minerals leached into
  water
• Heated water forces its way to surface
• High temperature (400C for black smokers), low
  pH (2.8, snails unable to form CaCO3 shells),
  high H2S
• Vents form at sites of seafloor spreading or
  back-arc basins (where melted subduction plates
  re-emerge)

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Plate tectonics
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Vent site
Sulfur bacteria
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Vent in action (Click to play, will not work
online)
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Trophic food web

• Bacteria feed on minerals
• Plankton feed on bacteria
• Suspension feeders
• Bacterial mats convert CO2 to organic compouds
• Food for grazers gastropod
• Chemosynthetic symbiosis
• Supply fixed carbon to host
• Host is food for predators
• Still dependent on oxygen, despite lack of light

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Tubeworm Riftia pachyptila
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Tubeworm Riftia pachyptila

• Gutless animal, sole nutrients come from bacteria
  lining its tube
• No need for organs or specialized tissues
• Access to a greater volume of water than bacteria
• Able to weather transitions between oxygen-rich
  to sulfide-rich water
• Settled juveniles have a complete gut, feed on
  plankton
• No larvae have been found

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Vent shrimp Rimicaris exoculata(rift shrimp
without eyes)
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Vent shrimp Rimicaris exoculata

• Most vent species do not have symbiotic bacteria,
  which must be ingested/consumed
• Nutrients passed up through food chain
• Contain sulfur metabolizing bodies in gills
• Despite poisonous effect of H2S on respiratory
  system, must be done for bacterial activity
• Some organisms store sulfur deposits for later use

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Vent shrimp Rimicaris exoculata
Mitochondria surrounding sulfur metabolizing body
Mitochondria in detail Single bounding membrane
Membrane stacks
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General info

• Vents may live for as long as 30 years
• Seismic activity can shut them off suddenly
• No clear dispersal method for inhabitants
• Several species have only been found at 1 or 2
  sites, suggesting site-specific evolution
• Some shrimp with vision pigments are found in
  both Mid-Atlantic Ridge and Pacific trenches
• Difficulty in long term study or culture attempts
• Pressure effects, light quality, recreate vent
• Feasibility for extended visits

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Pacific and Atlantic connection
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Adaptations of a Tropical Swamp Worm, Alma emini,
for Subsistence in a H2S-Rich Habitat Evolution
of Endosymbiotic Bacteria, Sulfide Metabolizing
Bodies, and Novel Processes of Elimination of
Neutralized Sulfide Complexes

• John N. Maina and Geoffrey M. O. Maloiy

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Study site Lake Victoria, Africa

• Area characterized by rapid growth of closely
  packed emergent vegetation and intense
  decomposition of the luxuriant plant matter
• Depth of organic matter deposit accumulated over
  many years ranges from 20 to 60 meters
• Anoxia hypercarbia begins within1-2 cm depth

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Biological sulfur cycle
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Alma emini

• Abundant in floating mats of papyrus swamp
• Success aided by ability to extract molecular O2
  from air (can survive without O2 for weeks)
• Posterodorsal section spreads to form a temporary
  respiratory groove, highly vascularized

bacterial cell
Sulfur metabolizing bodies
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Sulfur manipulation

• Binds to oxygen receptor sites in hemoglobin
• Sulfur metabolizing bodies (SMBs) convert H2S
  that diffuses into the body into less toxic or
  nontoxic forms, which are passed to bacteria,
  which metabolize them to ATP
• Use sulfur as electron donor
• After detoxification, sulfide complexes are
  voided by excision of epithelial cell blebs and
  exocytosis of crystalline like-bodies

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Crystalline-like sulfide complex
exocytosis
Excision of cyto- plasmic bleb

• Epithelial cell
• cytoplasmic extension

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Beggiatoa
Sulfur granules
Beggiatoa bacterial mat
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Website articles

• Astrobiology Travels to the Indian Ocean
• www.space.com/searchforlife/indian_ocean_010504.ht
  ml
• Nature The Abyss Live
• www.bbc.co.uk/nature/programmes/tv/abysslive