Tuesday, April 13, 2010

Vetiver Shows Promise for Removing Antibiotics from Water

What goes in must come out, and when animals are given antibiotics, they can find their way into the water supply. Now, a Michigan Tech senior has identified one way to sop them up.

Antibiotics, like many pharmaceuticals, pass through the digestive tract largely unchanged. The resulting drug-laden waste from farms and feedlots (or for that matter, apartments and subdivisions) may be treated, but conventional methods don’t break down excreted antibiotics.

Although the concentrations are small, probably not enough to have an immediate effect on anyone drinking a cup of water, scientists fear that releasing antibiotics indiscriminately into the environment encourages the development of antibiotic-resistant strains of bacteria and make it harder to treat deadly infectious diseases, such as drug-resistant tuberculosis.

“There are also problems with using this contaminated waste to fertilize crops, or the water to irrigate,” says Stephanie Smith, who graduates in May with a BS in Biochemistry and Molecular Biology. Working with Rupali Datta, an associate professor of biological sciences, Smith designed an experiment using sterile Vetiver to address the issue.

Vetiver is a native of India often grown in constructed wetlands to cleanse wastewater. It is both vigorous and noninvasive, and has been used to clean up some tough customers, including TNT.

Smith grew Vetiver hydroponically in a greenhouse, exposing the plants to various concentrations of tetracycline and monensin, two antibiotics commonly used to treat dairy cattle. “We wanted to see if the Vetiver would uptake them, because if you give these antibiotics to cows, 70 percent is excreted in active form,” Smith says. “We worry that they’ll leach into the groundwater, get into drinking water and compound the problem of antibiotic resistance.”

At the end of the 12-week study, all of the tetracycline and nearly all (95.5%) of the monensin had disappeared from the hydroponic solution. Tests confirmed that the Vetiver had absorbed and metabolized both drugs into its tissue. The result)s are preliminary, says Smith, but they show that Vetiver holds promise for remediating antibiotics in wastewater.

Smith also recorded a peculiar side effect. “The Vetiver in the tetracycline solution grew faster, much faster than the controls,” she says. “The plants in monensin grew somewhat faster.”
Next, the plants will be analyzed to determine what ultimately happens to the antibiotics within the plant tissue.

Smith’s research project was supported by a Summer Undergraduate Research Fellowship, funded by Michigan Tech.

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