Magazine article Science News

Plants Recruit Oil-Detoxifying Microbes

Magazine article Science News

Plants Recruit Oil-Detoxifying Microbes

Article excerpt

The 1991 Gulf War brought oily devastation to much of the Persian Gulf region (SN: 11/16/91, p.316). But testifying to this environment's resiliency, signs of a natural recovery are emerging--even around the perimeter of former oil lakes created by war-ravaged pipelines and wells. From this defiled desert landscape, wildflowers reemerged unexpectedly last year.

Biologists analyzing the spring-blooming plants' tentative comeback now believe they may have unearthed--literally--the roots of a natural, low-tech, and relatively low-cost strategy for cleansing oiled soil: plant cultivation.

"These plants should not have grown at all, because oil contains aromatic compounds, which are toxic," observes Samir Radwan, who led the probe. But when he and his colleagues at the University of Kuwait in Safat dug into the crude-soaked desert, they found the wildflowers' roots not only healthy but free of oil (see photo).

The only logical explanation, Radwan says, was that the roots recruited ubiquitous oil-degrading microbes to clean up. So his team cultured bacteria and fungi residing in the oily sand. And in the July 27 Nature, they report that the root zone was indeed a rich reservoir of well-known oil-eating microbes.

Immediately adjacent to the roots, one family of bacteria (Arthrobacter) accounted for fully 95 percent of the resident microbes. "But go out just 1 centimeter from the root and you find a completely different microflora [community of fungi and bacteria]," Radwan observes. These organisms, too, degraded oil, the microbiologist reports.

The annuals that his team studied in the desert belong to the same family as sunflowers (Compositae). To find out what other plants might survive, the Safat team tainted the sand in greenhouse pots to match the petroleum concentrations in which the wildflowers had been growing--10 percent crude oil by weight. …

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