While assays can’t remove contamination from a product, tests that produce timely, accurate results—and can be done cost-effectively in house by operations personnel—can go a long way in helping processors understand where issues may occur and prevent contaminated products from leaving a plant.
That’s where a new assay for Listeria comes in. Basically, it couples bacteriophages, which recently have been used to kill bacteria on food equipment surfaces and in food, (see FE, September 2007), with new biotechnologies. When the new test is combined with hardware and software, it can detect down to one Listeria organism—without an enrichment phase—within one shift.
Michael S. Koeris is a co-founder of Sample6, a company dedicated to producing detection solutions for bacteria. Koeris and his partner, Prof. Tim Lu, both worked on their PhDs at HHMI/BU, the preeminent lab in the emergent discipline of synthetic biology, and MIT’s Center for Synthetic Biology, where Lu continues his work.
FE: How did Tim Lu and you get together and come up with this solution?
Koeris: We started working on developing an information delivery system to address bacterial populations during our time in Jim Collins’ lab (at HHMI/BU). Bacteriophages offer a system to do just that, as they naturally and very specifically target only bacteria. We then set out to develop methods to encode different kinds of information in these delivery vehicles. Using synthetic biology methods, we developed the first instantiation of what became the Bioillumination Platform.
FE: What kind of samples can be taken?
Koeris: Our test is currently certified by the AOAC as the only enrichment-free, in-shift pathogen test for use on steel surfaces. We are working on future applications to include the sampling of finished product, air or other kinds of samples.
FE: What is the biotechnology side of this system?
Koeris: The bacteriophages naturally exhibit a very tight specificity for certain bacteria. In this case, we selected the phages to be very specific and only detect Listeria. The phages—upon interacting with the bacterial cell—force the bacteria to express an enzyme. This enzyme is derived from deep-sea shrimp, but it is fundamentally related to the firefly enzyme that many people might be familiar with (it makes fireflies glow). In essence, our phage turns any Listeria bacteria into miniature fireflies!
FE: How does your engineering background figure into your invention?
Koeris: Once we focused on the food industry, it became clear that the current microbiological methods weren’t suited to enabling statistical process control on the factory floor. It’s not optimal to have a long-cycle feedback loop and hope you’ll be able to control your system. Current methods with enrichment and shipment to off-site laboratories generally are unable to provide that critical, timely feedback. Our system closes the loop within one shift, so processors and producers are able to ensure they’re in control of their production before the product is shipped off to distributors or customers.
FE: In a nutshell, how does this rapid test compare with other “rapid tests” on the market?
Koeris: The key advantage of the Sample6 DETECT system is that you do not have to enrich your sample, which enables onsite execution of the test. We also paid great attention to making the test user friendly and robust: Just take the sample, add our solution to the sponge, wait for a few hours and read the samples.
FE: What roles do the hardware and software play in this testing procedure?
Koeris: Our hardware is a sensitive light reader, or luminometer, that is critical to enabling the sensitivity of our assay. At the same time, it’s not an expensive piece of equipment, allowing widespread deployment within an organization. The software takes care of interpreting the results, as well as coordinating the schedule of test taking and the recordkeeping of results and remediations.
FE: What level of expertise does an operator need to collect samples and run the test in its entirety including interpreting results?
Koeris: The system has been designed to be very user friendly and robust. Operators are able to start using the system after a short on-boarding training, which is now performed onsite by our customer success staff. The software makes the calls on individual samples of presumed positives or negatives.
FE: How does your system work with an existing FSMA HARPC (hazard analysis and risk-based preventive controls) system or FSMS (food safety management system)?
Koeris: Our system works well with existing preventive control systems, such as existing environmental testing plans. Our customer success team works with each individual site to import a map of the facility and place all the test points, along with pictures and historical data, for a unique level of visibility into the environmental state of the plant. With this data, Sample6 CONTROL can serve all the needs of an environmental prerequisite program such as scheduling, test taking, remediation and logging activities. On top of that, Sample6 CONTROL is conceptualized as an open system. That means it accepts not only Sample6 DETECT data, but all other testing data as well, whether it’s qualitative or quantitative testing. Our mission is to secure the food chain, and we believe the ability to track, measure and overlay all environmental data will help food processors better understand their plants and address potential hazards quickly and effectively.
FE: What are your plans for detecting other pathogens?
Koeris: We want to provide the right tools for the industry. Therefore, we are receptive to our customers’ needs. For the time being, we are focusing on Listeria, Salmonella and E. coli detection.
FE: When you have a test for other contaminants (e.g., Salmonella and E. coli or STEC), will processors be able use one sample to test for more than one pathogen simultaneously?
Koeris: It is possible to have a multiplexed test that can be deployed to detect multiple pathogens. Our development is driven by the needs and requests of our customers.
FE: What’s the future of rapid testing?
Koeris: Two concepts continue to exert pull on test manufacturers—inline and online testing. Having quick tests that monitor the entire manufacturing envelope is key to ensuring a safe food supply.