This lends support to the idea that bacteria survive on energy from the crust, a process that could affect our knowledge about the deep-sea carbon cycle and even evolution.
For example, many scientists believe that shallow water, not deep water, cradled the planets first life. They reason that the dark carbon-poor depths appear to offer little energy, and rich environments like hydrothermal vents are relatively sparse.
But the newfound abundance of seafloor microbes makes it theoretically possible that early life thrivedand maybe even beganon the seafloor.
Some might even favor the deep ocean for the emergence of life since it was a bastion of stability compared with the surface, which was constantly being blasted by comets and other objects, Edwards suggested.
Still, current knowledge of the deep biosphere can fit on the head of a pin, Edwards said. Most seafloor bacteria uncovered in this study show little relation to those cultivated in labs, which makes experimentation difficult.
Rather than bringing bacteria to the lab, however, Edwards plans to bring the lab to bacteriawith a microbial observatory 15,000 feet below sea level.
Thanks to a $3.9-million grant awarded in March by the Gordon and Betty Moore Foundation, Edwards and over 30 colleagues will continue studying seafloor bacteria, but will also study their subseafloor cousins that cycle through the porous rock.
The first expedition of its kind, the drilling operation will penetrate 100 meters of sediments and 500 meters of bedrock.
Besides experiments aimed at learning how precisely these bacteria alter rock, the scientists will measure the diversity, abundance and relatedness of microbes at different depths.
|Contact: Terah DeJong|
University of Southern California