Novel Rapid Identification of Food Bacteria

Filed in archive Genomics, Proteomics and Bioinformatics on July 18, 2005

My undergraduate thesis was an attempt to customize a cheaper version of test kits for the rapid identification of bacteria belonging to the enterobacteriaceae family. Using pure cultures, it faired comparatively well with the commercial test kits then available in the market: API 20E and the Micro-ID system. Although I was able to bring down the costs dramatically, the time frame needed before the results were ready was still considerably long, i.e. around 12 to 24 hours, because the tests were based on physiological reactions.

Today, Sam Nugen, a graduate student in Cornell University's food science department, will present a paper at the Institute of Food Technologists Annual Meeting and Food Expo in New Orleans, about a rapid, less costly and sensitive new technique for detecting group A streptococcus, the bacteria that cause scarlet fever. Although the paper will focus on the detection of Streptococcus pyogenes, the authors claim that the technique can be applied to a wide variety of bacterial pathogens, including Escherichia coli.

The new thechnique is based on the use of reporter genes, with probes targeted at rRNA sequences unique to specific microbes.

"In a positive result, the capture probe attached to the rRNA target molecule anchors itself to a strip on a membrane. Since the reporter probe with a red dye is also attached to the rRNA molecule, as the material collects on a zone on the membrane, it turns the strip visibly red, much like with a pregnancy test."

The bonus: the whole process just takes about 35 minutes, much faster than traditional gene amplification techniques that may take many hours.

"We hope to see this technique commercialized, because it is very rapid compared to all the standard methods right now," said Nugen, the study's lead author, who designed the software.

Read the feature from Cornell University here.