A new technology promises to make detection of food pathogens easier and quicker. The new method could also one day provide homeland protection officials with a better, faster means of inspecting imported food. It could likewise be used to probe water supplies in order to obtain profiles of toxic microorganisms that may be present at low concentrations.
According to system developer Michael Ladisch, a professor of agricultural and biological engineering at Purdue University, the system concentrates microorganisms such as salmonella and other pathogens in food extracts, to help bring the microorganisms, if present, to a high enough concentration so that they are easier to detect. The Ladisch method uses hollow thread-like fibers that filter out the cells, representing a potential new tool for speedier detection.
“This approach begins to address the critical need of the food industry for detecting food pathogens within six hours or less,” Ladisch said.
Quick growth for faster detection
The Ladisch machine, called a continuous cell concentration device, could make it possible to routinely analyze food or water samples to screen for pathogens within a single work shift at food processing plants. Ladisch told Homeland1 that ideally you want to detect foodborne pathogens in one work shift, from start to finish, which means extracting the sample, concentrating the cells and detecting the pathogens.
Ladisch said his system concentrates microorganisms in about an hour, but by itself does not detect pathogens.
“Rather, it is a tool for enabling rapid detection by reducing the time required to obtain high enough concentrations of microorganisms so that they may be probed,” he said.
Salmonella through a straw
Details of the Ladisch technique appear in the November issue of the journal Applied and Environmental Microbiology. Findings showed the system was able to concentrate inoculated salmonella by 500 to 1,000 times the original concentration in test samples. This level of concentration is required for accurate detection.
Another finding showed the system recovered 70 percent of the living pathogen cells in samples, important because if filtered microorganisms are killed in the process that’s self-defeating.
The Ladisch machine was used to concentrate cells in samples of chicken meat. The sample was first broken down to the consistency of a milkshake, and then passed through 12 hollow-fiber filters about 0.3 mm in diameter that are contained in a tube about the size of a soda straw. The filtering process continues until pathogens, if present, are concentrated enough to be detected.
