MIT and Purdue partner to prove laser light scattering pathogen detection concept
The partnership, which will initially focus on listeria, pairs similar laser light scattering technologies developed independently to demonstrate the speed and accuracy of using non-biological methods for food pathogen testing.
It aims to be an improvement over the two to three hours needed for polymerase chain reaction (PCR) results.
Dr David Haavig, Micro Imaging Technology's chief scientist, is the program director of the effort and will lead MIT in the collaboration.
FDA funding proposal
A funding proposal has been submitted to the FDA for a grant based on the joint work which, if successful, will see the project start in June 2014, Haavig explained to FoodQualityNews.com.
“We have done thousands of tests on a variety of different strains including purposely contaminating chicken.
“What Purdue and we have to offer is compelling and I am sure we could find another vehicle for this funding if we needed, but what we have is a multi-phase process.
“The first phase is a proof of principle with listeria on food, to show and publish details that it works well and in phase two, which would be longer and cost more money, we would look at other pathogens and bacteria.”
He said that MIT tech researchers have illuminated individual cells before but for some reason nothing came of it.
The project has moved forward because of the time able to be dedicated to taking scattered light measurements and how they vary with specific species and strains.
“It could be within two and a half to three years to have all the information to prove that it works, but once results are in we could start marketing immediately,” he added.
3 minute identification
Dr Haavig helped develop the MIT 1000, a bacterial cell based identification system that can identify pathogenic bacteria in an average of three minutes.
The MIT System underwent ruggedness and accuracy tests to earn AOAC RI's certification for the identification of Listeria in 2009.
MIT’s device uses light scattering to detect various bacteria cells that are suspended in filtered water.
The firm said due to the small sample volume required, culture time is reduced by up to 50% compared to standard testing. Results can be obtained in eight hours from the time the culturing process begins.
Incident laser light reflects off the bacteria’s outer surface and penetrates the body of the bacterium, the light then interacts with any structural features and emerges from inside the cell.
These light patterns are unique for each species and create a signature that is captured and stored in a computer database.
MIT 1000 features 35 photo detectors that surround the sample vial and collect light scattering intensities that are generated when a cell intersects the laser beam.
The scattering values collected by the detectors are analyzed by MIT’s software that contains a database of values for each bacteria seen by the photo detectors.
Identification occurs when 10-50 organisms are analyzed and takes less than five minutes.
Purdue tech
Dr Arun Bhunia, professor of Food Microbiology at the Purdue University Department of Food Science, will direct the Purdue portion of the research with Dr Euiwon Bae, a mechanical engineer, at facilities in West Lafayette, Indiana.
Light scattering involves shining a sensor on a bacterial colony growing on an agar plate, which produces a scattered image which researchers can record and fingerprints each particular organism.
The time to identification depends on the time needed to grow the colony, 12 to 15 hours for E. coli O157:H7, Salmonella and 24 to 30 hours for Listeria.
Dr Bhunia and collaborators have built two prototype instruments, which they call BARDOT (BActerial Rapid Detection using Optical light scattering Technology).
