Oil-Eating Bug

Of all industrial accidents, few are messier than oil spills. Floating booms can contain surface oil and keep it from spreading while it is picked up and recovered by giant vacuum cleaners. Straw filters can be used to pick up oil that makes its way into shallow waters. But scientists have been trying for years to develop more effective methods of dealing with spills. Now one team seems to have succeeded. General Electric announced last week that scientists at its Schenectady, N.Y., laboratories have created a microbe that can eat petroleum in quantity.

The bug that eats oil is the result of nearly six years of work by Ananda Chakrabarty, 41, an Indian-born microbiologist. Like most of his colleagues, Chakrabarty knew that at least four strains of the common pseudomonas bacteria contained enzymes that enabled them to break down different hydrocarbons--the major ingredients of oil. He combined these strains into what he describes as a "superbug" that can eat oil faster than any one of the four can individually.

Healthy Appetite. Chakrabarty first determined that the genes for oil-degrading enzymes were carried not on the microbes' chromosomes, where most genetic material is found, but elsewhere in the cell. He discovered that although the "plasmids," as these genes are called, were isolated and transferred from one bacterium to another easily enough, the two batteries of genes he tested would not stay together in the same cell; nor could cells of different strains be paired. When they were, the bacteria competed with and inhibited each other.

Finally--after several experiments --Chakrabarty discovered that irradiating the host organisms with ultraviolet light after plasmid transfer induced a genetic cross-linking that fixed the new genes in place and produced stable bacteria with a healthy appetite for oil. The new microbe, to which Chakrabarty gives the jawbreaking description "multi-plasmid hydrocarbon-degrading pseudomonas," can digest about two-thirds of the hydrocarbons involved in an oil spill. The new microbes have been tested only in the laboratory, where a pinch of microbes will eat an eyedropper of oil in a matter of days. This may seem slow, but it is between ten and 100 times faster than the four other strains of oil-eating microbes can work.

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