OAR/National Undersea Research Program (NURP); NOAA
The ocean floor is a dark place for a photosynthetic bacterium. Nevertheless, researchers led by J. Thomas Beatty of the University of British Columbia, Vancouver, have found obligately photosynthetic green sulfur bacteria (GSB1) at a hydrothermal vent more than a mile below the ocean surface.1
Beatty and colleagues cultured water samples from the East Pacific Rise, an area with a variety of hydrothermal vents. GSB1 grew in just one sample, taken from within 50 centimeters of a vent.
Coauthor Cindy Van Dover of the College of William and Mary, Williamsburg, Va., has previously shown that geothermal radiation is mostly infrared but extends into visible wavelengths. Photon flux at 750 nm, which is what GSB1's bacteriochlorophylls absorb, is about the same as that available for a green sulfur bacterium found in the Black Sea. That bacterium has been estimated to take two to three...