Since mapping the human genome 10 years ago, J. Craig Venter has found plenty of work. The biologist now is burrowing into DNA in as many forms as he can discover, in organisms from the sea and deep underground. His goal: to use the building blocks found in naturally occurring DNA to make synthetic cells. He and his partners at Exxon Mobil Corp. and BP PLC believe genetically engineered life forms hold great promise for energy and other industries.

The Wall Street Journal's Alan...