The tricky task of pulling toxic pollutants out of groundwater may have just grown easier. By arming the microbes that dwell inside a plant with the ability to break down toluene, scientists have shown that the microbes and plants can thrive in soil so polluted it would otherwise quickly kill off plants. Such plants could be used to suck pollutants out of groundwater and break them down.
Once toxic industrial solvents have gotten into the soil, it's notoriously difficult and expensive to get them out. Scientists have discovered (and created) bacteria that break down pollutants, but getting the bacteria to thrive in contaminated soil is difficult, and many pollutants dissolve in groundwater before the bacteria can degrade them. Plants help by slurping up groundwater and giving the bacteria the time and place they need to work, but if the soil is extremely polluted, the plants die.
Now, a team led by microbiologist Daniel van der Lelie at Brookhaven National Lab in Upton, New York, and environmental biologist Jaco Vangronsveld from the Limburgs Universitair Centrum in Belgium has equipped yellow lupin plants with bacteria that help it cope with the common pollutant toluene. Infusing the plant with a strain of bacteria that degrade toluene sickened the plant, the team found. So they harvested microbes that normally live inside yellow lupin, harmlessly perching on the surface of cells, and allowed these bugs to mingle with the toluene-degrading bacteria. The lupin natives picked up the toluene-eating genes through a process of gene-swapping common among bacteria. The newly equipped microbes enabled the lupin to thrive in soil that killed plants harboring only the original, unequipped microbes, the team reports in the May issue of Nature Biotechnology.
"One of the problems with organisms designed in the cushy environment of the lab, where they have all the proper nutrients, is that they don't compete well in the field," says Todd Anderson, an environmental toxicologist at Texas Tech University in Lubbock. That probably won't be a problem here, he says. By starting off with microbes native to the plants, the team's method stands a good chance of allowing the organisms to survive long enough to degrade the pollutants he says.