Soil biochemist Jean-Marc Bollag also studies soil microorganisms, but he puts them to work. For more than 30 years, he has conducted research on bioremediation—the process of using microbes and plant parts to remove toxic chemicals from soils and wastewater.

Soils around the world have been contaminated with pollutants ranging from explosives and pesticides to various industrial chemicals. “About 40 percent of the organic chemicals that reach the soil remain there,” Bollag explains. “When you consider all the chemicals that have been applied to soils in the past 40 or 50 years, there’s reason for concern. We know very little about the toxic effects of these residues.”

Bollag and his research team use several approaches to remove or neutralize contaminants. For some problems, he hunts down specific microbes that will degrade the pollutant, then inoculates or encourages the organisms’ growth in the contaminated soil.

He also works with the microbial enzymes directly responsible for degradation. “We isolate the enzyme from the organism, stabilize it on a solid surface, such as soil or clay, then apply it to the contaminated soils,” he explains. “With this method, people don’t need to worry about the bacteria spreading. It’s not yet used commercially, but we believe this technique will be very useful.”

Bollag also has screened more than 100 plants for enzymatic activity. He’s used minced horseradish roots, which contain very active enzymes, to clean wastewater and soil. He’s currently exploring the use of wastes from Pennsylvania’s food processing
industry, including potatoes and mushroom stumps.

Bollag’s most recent approach uses microbial activities to bind toxic chemicals to the soil humus, which could solve contamination problems involving chemicals that don’t degrade easily.

The idea for this work dates back to the 1970s, when Bollag was looking for an organism that could break down an insecticide called carbaryl, or Sevin. “I gave a graduate student some fungi to work with, and the student returned and said, ‘The carbaryl molecules aren’t getting smaller—they’re getting bigger!’”

The molecules, it turned out, were forming chains, or “polymers.” The polymerization was catalyzed by a fungal enzyme called laccase.

Bollag found that laccase and other similar enzymes not only promote polymer formation, they promote the binding of many pollutants to the soil as well.

“Once pollutants are chemically bound in the soil, they’re not toxic anymore,” he explains. “They’re either locked up permanently, or they release very slowly until they disappear. This enzyme gives us another powerful tool for detoxifying soils.”

Bollag has used the technique on soils contaminated with TNT. People who eat, drink, touch, or breathe TNT-contaminated air or substances can develop anemia, liver problems, skin irritation, cataracts, and possibly cancer. TNT has been found in at least 20 of EPA’s 1,430 National Priorities List contaminated sites.

“Because TNT was the major explosive used during both World Wars, high concentrations are still found all over the world,” Bollag says. “You find it near former weapon factories, or anyplace where a lot of ammunition fell. The question always has been whether we move the soil away, which can be very expensive, or whether we can treat it in place. Now we’re answering that question. German scientists have used the process at a large TNT-contaminated site, and I was able to prove to the German environmental protection agency that the material is indeed chemically bound.”

Meanwhile, Bollag is applying his toolkit of strategies all over the world. He’s looking for microbial degraders in Syria; working with enzymes in Egypt; and giving talks on enzymes in Italy. “We collaborate with universities in Japan, Korea, Italy, Germany, Egypt, Syria, and Canada,” he says. “Graduate students come here to learn the techniques, then take them back to their country. Each has a different chemical or problem they’re working on, in one stage or another.”