Links to Other ASM Pages:



• Table of Contents
• ASM News Issues

Water Safety from Micro…

Golf courses, common along the South Carolina coast, may contribute to contamination of local waters. This golf course at the edge of the Waccamaw River was part of a study conducted by the North Inlet-Winyah Bay National Estuarine Research Reserve designed to determine the effects of golf course best management practices on water quality. (National Oceanic and Atmospheric Administration/Department of Commerce photo.)

Recently heightened concerns over terrorism are among the forces driving the development of highly sensitive, pathogen-detection systems for testing the safety of water, according to Ray Mariella, Jr., of Lawrence Livermore National Laboratory (LLNL) in Livermore, Calif. Mariella was one of several experts who participated in a workshop, "Indicators for Waterborne Pathogens," convened early in September by the National Research Council (NRC), the working arm of the National Academy of Sciences (NAS) in Washington, D.C. In general, officials charged with evaluating the safety of drinking water supplies can benefit from using such sophisticated analytic tools.

Researchers at LLNL have developed a battery-powered, hand-held, PCR-based device that provides "a powerful means for typing" pathogens, including Bacillus anthracis, that conceivably could be introduced into water supplies, Mariella says. But it is neither simple nor cheap to operate, making this otherwise versatile device not very well suited for use in developing countries. Such devices also are not particularly well suited for detecting scarce, extremely dilute, but highly potent waterborne parasites, such as cryptococcal oocysts, he points out. "You can get negative results because of sampling errors." A team at LLNL is developing a method whereby acoustic energy is used to concentrate particles as they flow through a channel, and plans to assemble thousands of such miniature devices to handle large volumes of water containing low pathogen loads.

With similar aims, researchers at Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tenn., are studying microfabricated fluidic devices that depend on electrokinetic energy or capillary forces to move tiny volumes of particle-containing fluids through microscale channels, according to J. Michael Ramsey of ORNL. Coupled with miniature PCR reactors or antigen-based detectors, such devices can give readouts within a few minutes. Still other experimental schemes use dielectrophoresis to separate particles contained in water or employ microfluidic techniques to test signature DNA molecules contained in very low-volume samples, according to Mariella. However, although promising, these new techniques are not ready for handling large-scale water samples, he says.