SAN DIEGO – In a laboratory where almost all the test tubes look green, the tools of modern biotechnology are being applied to lowly pond scum.

Foreign genes are being spliced into algae and native genes are being tweaked.

Different strains of algae are pitted against one another in survival-of-the-fittest contests in an effort to accelerate the evolution of fast-growing, hardy strains.

The goal is nothing less than to create superalgae, highly efficient at converting sunlight and carbon dioxide into lipids and oils that can be sent to a refinery and made into diesel or jet fuel.

“We’ve probably engineered over 4,000 strains,” said Mike Mendez, a co-founder and vice president for technology at Sapphire Energy, the owner of the laboratory. “My whole goal here at Sapphire is to domesticate algae, to make it a crop.”

Dozens of companies, as well as many academic laboratories, are pursuing the same goal – to produce algae as a source of, literally, green energy. And many of them are using genetic engineering or other biological techniques, like chemically induced mutations, to improve how algae functions.

“There are probably well over 100 academic efforts to use genetic engineering to optimize biofuel production from algae,” said Matthew C. Posewitz, an assistant professor of chemistry at the Colorado School of Mines, who has written a review of the field. “There’s just intense interest globally.”

Algae are attracting attention because the strains can potentially produce 10 or more times more fuel per acre than the corn used to make ethanol or the soybeans used to make biodiesel. Moreover, algae might be grown on arid land and brackish water, so that fuel production would not compete with food production. And algae are voracious consumers of carbon dioxide, potentially helping to keep some of this greenhouse gas from contributing to global warming.