'Scuba gear' for biotech bugs.

Biotechnologists have genetically engineered many bacteria to behave as little chemical factories. Under the direction of their foreign genes, these microbes inexpensively produce commercially important proteins -- from hormones to enzymes. However, genetically engineered aerobic bacteria tend to consume a lot more oxygen than non-engineered bacteria, studies have shown. And as those microbial factories deplete their oxygen supplies, their production of protein slows dramatically, notes IIT biologist Benjamin C. Stark.

His team believes it had found a solution in hemoglobin, the same protein that carries oxygen in human red blood cells.

Five years ago, IIT's Dale A. Webster shared in the discovery of a bacterium with hemoglobin (SN: 8/23/86, p.120). Though this Vitreoscilla needs oxygen to survice, the bacterium often resides in low-oxygen environments, such as cow dung. The microbe survives by using hemoglobin "sort of like scuba gear for bacteria" -- to help it breathe, Stark says. He and his colleagues are now working to imbue genetically engineered bacteria with the same oxygen-support system.

They have spliced the Vitreoscilla hemoglobin gene into another bacterial strain that has been genetically engineered to produce alpha-amylase, an enzyme used in the commercial production of high-fructose corn syrup. In recent tests, Stark says, those bugs engineered to make hemoglobin grew better and produced more alpha amylase than the same engineered bacteria lacking hemoglobin: "Under the best circumstances, you get more than a 200 percent increase in the alpha amylase produced."