Hydrothermal Vents I:
Chemoautotrophs
Chris Choe
Hydrothermal Vents I
• Vents on bottom of ocean
from which superheated
water flows
• Form near areas with
tectonic and volcanic activity.
BBC
NOAA
Hydrothermal Vents II
Hydrothermal Vents III
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Water picks up and ejects
minerals
Notably, dissolved sulfates
in water are converted to
hydrogen sulfide through
superheating
Autotrophs can use
hydrogen sulfides for
chemosynthesis
Note: Not all hydrothermal
vents vent the same
minerals. “Black smokers”
tend to vent iron sulfides,
“white smokers” silicon,
calcium, and barium
compounds. Some just vent
methane and hydrogen,
etc.
Indiana State University, 2013
Chemoautotrophs
• Hyper (or super) thermophilic chemo-autotropic bacteria are
effectively the sole autotrophs for hydrothermal vents.
• Provides the foundation for hydrothermal vent communities.
• However, bacteria are generally not free-ranging; tend exist in
symbiotic relationships with invertebrates near the vent.
• Major Symbionts
– Tube worms
– Molluscs
Beggiatoa mats
Sulfur Bacteria
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Bacteria that oxidize sulfides are the most common autotrophs in hydrothermal
vent communities.
However, most can also undergo heterotrophic growth.
~37% of species can undergo fermentation, ~88% can do denitrification.
Sulfur reduction is also used
In general, bacteria have multiple methods for generating energy and carbon
compounds.
State College of Florida, 2013
Methylotropes/Methanogens
• Methanogens are bacteria that produce methane from carbone dioxide to
generate energy.
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Includes substrates like carbon dioxide, methanol, acetic acid
General reaction is CO2 + 4 H2 → CH4 + 2 H2O
Coenzyme M reductase is inhibited by sulfite (necessary for methanogenesis)
Sulfides react with oxygen to make anaerobic conditions (favors methanogenesis)
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Fortunately, evolution allows hydrothermal vent methanogens to function regardless.
• Methylotropes use one-carbon sources to generate energy
– Substrates include cyanide, carbon monoxide, and methylamines
Teske et al 2003
ScienceDaily 2008
Iron, Manganese, Ammonium, Hydrogen
• Autotrophs using these elements are generally less important
than the ones using sulfur or one-carbon compounds
• However, they still can play a substantial role in some
hydrothermal vent communities, depending on the exact
minerals/elements spewed out by the vents in the area.
• Not much information on these bacteria and their role in
hydrothermal vent communities as of yet.
ScienceDaily 2011
Photosynthesis?!
• In a word: yes.
• Robert Blankenship found green sulfur bacteria in a black
smoker vent field in 2003
• Bacteria was capturing geothermal radiation using pigments
and chlorosome, a photosynthetic antennae complex.
– “An obligately photosynthetic bacterial anaerobe from a deep-sea
hydrothermal vent” (Beatty, 2005)
ASU 2005
Tube Worms (Giant Tube Worm)
• Related to tube worms closer to the surface
• Red plume exchanges compounds with environment, white tube attached
to vent surroundings
• Has no mouth or digestive tract: has specialized organ (troposome) for
chemo-autotrophic bacteria.
• Bacteria provide tube worm with carbon compounds, tube worm provides
bacteria with shelter, oxygen, and nitrates.
• Bacteria constitute over 50% of total body mass. Hemoglobin is active in
the presence of sulfides and reversibly binds to it.
Stephen Low Productions
Bivalve Molluscs
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Grow in crevices around vents
Lack guts, completely reliant on chemosynthetic bacteria for organic compounds
Bacteria grow in gills; clams provide carbon dioxide through gills, as well as shelter
and proximity to vent minerals.
Bacterial colonies passed on during fertilization.
Bacterial colonies are not necessarily sulfur-based; colonies can be of different
species, and can include methanogens.
Damm, 2002
Bathymodiolus
Monterey Bay Aquarium Research Institute
Calyptogena
Bibliography
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1: ”Deep sea vents: Exploring a strange world.” BBC, 20 Feb 2013 <http://www.bbc.co.uk/news/science-environment-21463274>
2: ”Global compilation of confirmed and inferred vent sites.” NOAA Vents Program <http://www.pmel.noaa.gov/vents/PlumeStudies/globalvents/index.html>
3: “Deep Hot Springs Discovered.” Marum Center for Marine Environmental Sciences <http://www.marum.de/en/07.10._Deepsea_hot_springs_discovered.html>
4:”Deep Sea Vent Communities: Did Life Originate in the Abyss?” Indiana State University, 2013
<http://www.indiana.edu/~g105lab/images/gaia_chapter_13/vent_communities.htm>
5: “MARINE ENVIRONMENT AND PRIMARY PRODUCTIVITY”, State College of Florida, 2013
<http://faculty.scf.edu/rizkf/OCE1001/OCEnotes/chap11.htm>
6: “Deep Sea Vent Mussels” Monterey Bay Aquarium Research Institute. Dec 17, 2009 <http://www.mbari.org/molecular/mussels.htm>
7: Damm, Karen Von. “Crew Log of Karen Von.” University of New Hampshire 2002 <http://www.divediscover.sr.unh.edu/010902.html>
8: Tseke, Andreas. “Gulf of Mexico Cruise Log” November 2010 <http://teskelab2010.files.wordpress.com/2010/11/2010_11_23_17_22_48sm.jpg>
9: “Quakes Under Pacific Floor Reveal Unexpected Circulatory System” The Earth Columbia Research Institute (picture from National Science
Foundation) January 10 2008 <http://www.earth.columbia.edu/articles/view/2019>
10: Beatty, Thomas “An obligately photosynthetic bacterial anaerobe
from a deep-sea hydrothermal vent” PNAS March 3 2005 http://www.pnas.org/content/102/26/9306.full.pdf
11: “Giant Tube Worm, Riftia pachyptila” RedOrbit 2013
http://www.redorbit.com/education/reference_library/science_1/annelids/1112652622/giant-tube-worm-riftia-pachyptila/
12: “Hydrogen-Powered Symbiotic Bacteria Found in Deep-Sea Hydrothermal Vent Mussels” ScienceDaily Aug 11 2011
http://www.sciencedaily.com/releases/2011/08/110810132832.htm
13: “Researchers find photosynthesis deep within ocean” Arizone State University. June 15, 2005
http://www.asu.edu/feature/includes/summer05/readmore/photosyn.html
14: "East Pacific Vent at 9degN, 2,600meters on Tube Worm Pillar. Giant tubeworms form a large bush. “ Stephen Low Productions
http://www.noc.soton.ac.uk/chess/event/galapagos_event.php
15:”Lost City Pumps Life-Essential Chemicals At Rates Unseen At Typical Deep Ocean Hydrothermal Vents” ScienceDaily Feb 5 2008
http://www.sciencedaily.com/releases/2008/01/080131151856.htm
16: Teske et al. “Genomic Markers of Ancient Anaerobic Microbial Pathways: Sulfate Reduction, Methanogenesis, and Methane Oxidation “ The
Biological Bulletin 2003 http://www.biolbull.org/content/204/2/1