Purdue News

April 14, 1986

Purdue Researchers Develop Speedy Method To Identify Diseases

West Lafayette, Ind. — Researchers at Purdue University have developed a method of using laser beams to identify diseases in plants in less than half the time used by current techniques.

The new method, which uses laser beams to measure the amount of nutrients consumed by bacteria, may someday be used to expedite the identification of human diseases, says Fred E. Lytle, professor of chemistry at Purdue and director of the project.

"The idea behind our technique is to identify pathogens at very low numbers of cells. Pathogens can now be identified at high numbers of cells--but it may take 24 to 48 hours to culture enough cells to use these techniques. Our goal is to see if we can fit the whole analysis into a technician's work day," says Lytle.

The method uses a rapid, laser-based fluorimetric system to measure the amount of amino acids consumed by pathogenic bacteria. Amino acids tagged with the highly fluorescent material betanaphthylamine are fed to a small number of bacterial cells. As the nutrients are consumed, the betanaphthylamine is released and recorded by a laser-based fluorimeter.

By noting the specific types and amounts of nutrients consumed, researchers can identify many common pathogens, including most bacteria and fungi, says Lytle. The new technique cannot, however, identify viruses at this time, he adds.

"This method of identifying disease-causing organisms has been used for many years. By adding a laser to pick up minute emissions, we have been able to cut the number of bacteria cells needed for a positive identification back by a factor of 100 to 1,000 times," he says, noting that pathogens in plants have been identified with cell counts as low as 50,000 per milliliter.

In addition, the Purdue team has used the method to distinguish among different species and races.

"By employing the use of pattern-recognition techniques, we can break the information down enough to separate the pathogens into genera and races," he says.

Lytle hopes to see his method someday used in the identification of human diseases. "We are still working to refine the technique and find new ways of using even fewer cells. But evidence from our current research indicates that the technique could be easily applied to human pathogens," he says.

Information on the pathogen-identification system will be presented in New York City this week during the American Chemical Society's national meeting. J. T. Coburn, a recent Ph.D. graduate from Purdue who now works as a research scientist at BASF Wyandotte Corp., Wyandotte, Mich., will present details of the techniques used.

The project is a collaborative effort among Lytle; Don M. Huber, professor of plant pathology; Ben S. Freiser, professor of chemistry; Bob Forbes, a chemistry graduate student; and Laura Becker, an undergraduate student, all at Purdue.

Purdue News Service: (765) 494-2096; purduenews@purdue.edu