Photos Poison or Fuel?
More than a mere biological oddity, the discovery adds weight to Oremland's theory that the bacteria's ability evolved billions of years ago, when the first life was just getting started on Earth. At the time, the planet's oceans were devoid of oxygen, but hydrothermal vents spewed elements such as sulfur, iron and arsenic into the water column. In this ancient stew, arsenic may have been an important nutrient to life. The life forms would have used whatever they could to survive these noxious waters, and sunlight and arsenic were probably plentiful. As the life forms found they could make a living off of these odd bedfellows, one of the first forms of photosynthesis was born. Photosynthesis may be the most important biochemical machine on the planet. Modern plants, from the biggest trees down to microscopic algae floating in the ocean, use sunlight, water and carbon dioxide to fuel photosynthesis, and they in turn supply the oxygen that nearly every animal on the planet breathes. Felisa Wolfe-Simon of Harvard University said that's what makes the team's discovery so fascinating -- in effect they've uncovered a prototype of photosynthesis. Modern photosynthesis is thought to have evolved between 2.3 and 2.7 billion years ago. The arsenic-based form may be much, much older. "The move to the modern form of breaking up water molecules was the biggest move" in the evolution of photosynthesis, Wolfe-Simon said. "But along the way the innovations in the machinery are very interesting." Related Links: |
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