Chapter 9, Additional Exercise 4: Revising a Passage in a List Format

Revise the following passage (based on J. D. Snyder, 1993, “Off-the-shelf bugs hungrily gobble our nastiest pollutants,” Smithsonian, 24, 66+) using a list format. The subject is bioremediation, which is the process of using microorganisms to restore natural environmental conditions.

Scientists are now working on several new research areas. One area involves using microorganisms to make some compounds less dangerous to the environment. Although coal may be our most plentiful fossil fuel, most of the nation’s vast Eastern reserve cannot meet air-pollution standards because it emits too much sulfur when it is burned. The problem is that the aromatic compound dibenzothiophene (DBT) attaches itself to hydrocarbon molecules, producing sulfur dioxide. But the Chicago-based Institute of Gas Technology last year patented a bacterial strain that consumes the DBT (at least 90 percent, in recent lab trials) while leaving the hydrocarbon molecules intact.

A second research area is the genetic engineering of microbes in an attempt to reduce the need for toxic chemicals. In 1991, the EPA approved the first genetically engineered pesticide. Called Cellcap, it incorporates a gene from one microbe that produces a toxin deadly to potato beetles and corn borers into a thick-skinned microbe that is hardier. Even then, the engineered bacteria are dead when applied to the crops.

A third research area is the use of microorganisms to attack stubborn metals and radioactive waste. Microbes have been used for decades to concentrate copper and nickel in low-grade ores. Now researchers are exploiting the fact that if certain bacteria are given special foods, they excrete enzymes that break down metals and minerals. For example, researchers at the U.S. Geological Survey found that two types of bacteria turn uranium from its usual form—one that easily dissolves in water—into another one that turns to a solid that can be easily removed from water. They are now working on doing the same for other radioactive waste.