Food Production Daily reports that researchers at Purdue University have developed a new system that analyzes scattered laser light to quickly identify bacteria for applications in medicine, food processing and homeland security at one-tenth the cost of conventional technologies.

The technique, called Bacteria Rapid Detection Using Optical Scattering Technology, works by shining a laser through a petri dish containing bacterial colonies growing in a nutrient medium.

The work was started by Arun Bhunia, a professor of food microbiology and Daniel Hirleman, head of Purdue’s mechanical engineering school.

The machine bounces particles of light, called photons, off of a bacterial colony. The pattern of scattered light is projected onto a screen behind the petri dish. Individual bacterial colonies growing in a petri dish distort light passing through them, just as a lens changes light-wave patterns. The "light-scatter pattern" is recorded with a digital camera and analyzed with sophisticated software to identify the types of bacteria growing in the colonies.

The procedure identifies a bacterial colony by comparing an image of its scatter pattern against a template that contains 120 features described by Zernike polynomials. The reduced collection of numbers describes how well the colony fits the template, and then pattern recognition software is used to classify the bacteria.

The researchers used the new system to classify six species of listeria, only one of which is a dangerous food-borne pathogen for humans. The scientists used to system to accurately identify other types of bacterial colonies, including salmonella, vibrio, E. coli and bacillus.

The technology does not require complicated lab equipment. A system could be designed so that it wouldn’t require someone with a doctoral degree to operate.

The researchers have filed a provisional patent for the data-processing technique, and a full patent application has been filed on the underlying light-scattering technology.