Using Lasers to Detect Mutant Bacteria

Using lasers to detect harmful bacteria is a topic of interest to more than a few researchers. Previously, we highlighted developments where lasers were used to identify contaminated food, which may be used to stop food poisoning long before contaminated food hits a dinner plate. Now, researchers at Purdue University have developed a laser tool that not only detects harmful bacteria, it also recognizes mutated strains.

The tool, known as bacteria rapid detection using optical scatter technology or BARDOT, works similar to the TDLAS method developed at the Institute of Information Optics, Zhejiang Normal University, Jinhua, China. BARDOT scans colonies of bacteria, revealing patterns created the bacterium. Each type of bacteria has a unique “scatter pattern” which is used to help identify the strain, against known scatter patterns. Like TDLAS, bacterium such as salmonella, E. coli, and listeria can be identified in a short period of time.

What separates BARDOT from TDLAS and other bacteria-detecting scans? According to researchers Arun Bhunia and Atul Singh, BARDOT is also able to detect genetic mutations in listeria, and at the same rate that it detects other strains of bacteria. Even more intriguing is the fact that BARDOT can detect the mutations faster than scientists can physically analyse the bacteria, themselves. Where traditional analysis of mutated bacteria takes a handful of days, BARDOT takes hours to “read” a bacterial scatter pattern.

The researchers tested BARDOT by allowing it to analyse a regular, wild listeria pattern, then deleting a gene in the system. BARDOT was able to recognize the system with the deleted gene as a listeria pattern. When the original gene was replaced, BARDOT still recognized it as the initial type of bacteria, despite the major genetic change, or mutation.

Where TDLAS has already been tested and proven effective on biological surfaces, Bhunia plans to build a larger library of known bacterial patterns before testing BARDOT as a way to detect food contamination. The details of the findings can be found here, through the American Society of Microbiology.