Food contamination is a serious global health issue. According to the WHO, an estimated 600 million, almost 1 in 10 people globally, suffer from illness after eating contaminated food—and 420,000 die. Developing new technologies for more effective testing of food contaminants can help reduce that number and improve public health.
A recent application of bioluminescent technology could change the way we test for mycotoxins in the future. Dr. Jae-Hyuk Yu, Professor of Bacteriology at the University of Wisconsin-Madison, and his then graduate student, Dr. Tawfiq Alsulami, collaborated with Promega to develop a bioluminescent biosensor that enables simple and rapid detection of mycotoxins in food samples.
What Are Mycotoxins?
Mycotoxins are toxic secondary metabolites produced by certain molds and are commonly found in food products. The occurrence of mycotoxins is widespread throughout the world, estimated to contaminate about 25% of global food crops. They are a major concern in the food industry, because consuming mycotoxins can lead to serious health risks such as acute poisoning, cancer, and immune deficiencies. “It’s a really big issue. We tested some samples from my local supermarket and found mycotoxins, which means it’s really prevalent everywhere,” says Dr. Alsulami. So far, around 330 mycotoxins have been identified, but only 6–7 frequently contaminate human food. Of those, the most common mycotoxin contaminant in corn products, such as cereals, is fumonisin. Fumonisins can have serious adverse health effects in livestock and other animals.
Current Methods to Detect Fumonisin
Fumonisins are unique in that they are water-soluble and particularly difficult to detect. Traditionally, fumonisins are detected using either high performance liquid chromatography (HPLC) or immunoassays—both of which are tedious and time-consuming. Preparing samples for HPLC involves extraction and cleanup steps. It also requires expensive equipment and technical expertise to run samples. Immunoassays are simpler than HPLC, but they often have too many steps of washing and incubation, or the sensitivity is low.
Using NanoBiT® Technology for Detection of Mycotoxins
To solve the problems with current methods for detection of mycotoxins, Dr. Yu and Dr. Alsulami collaborated with Promega scientists to develop a biosensor for detecting fumonisin B1 (the most common type of fumonisin) using NanoBiT® technology. In the NanoBiT®protein complementation system, a NanoLuc® luciferase enzyme is split into two subunits: LgBiT and SmBiT. When the two subunits are in proximity, they re-form the luciferase enzyme and generate luminescent light. “I saw the very unique strength of NanoBiT. It gives a nice signal without interference. NanoBiT has been used in so many fields so far, so applying this to mycotoxin testing seemed to be a very good idea,” says Dr. Yu.
How the Biosensor Works
The biosensor they developed, called FNanoBiT, has two main components: 1) LgBiT-tagged antibody that binds to fumonisin (FLgBiT), and 2) SmBiT-tagged fumonisin B1 (FSmBiT). When no natural fumonisin B1 is present, the antibody works as a bridge to bring SmBiT and LgBiT together, generating a luminescent signal. However, when natural fumonisin is present, it competes with FSmBiT, forcing SmBiT and LgBiT further apart, which reduces the light signal. Therefore, a low luminescent signal indicates high fumonisin B1 concentration.
Collaborating with Promega
Developing the biosensor was not easy. Luckily, they received ongoing support from Promega R&D Scientist, Dr. Nidhi Nath. He trained Dr. Alsulami on using the NanoBiT® system, and even served on his graduate committee. “I was so lucky to know the people at Promega,” says Dr. Alsulami. “They taught me how to use the system and provided us the materials. They were so nice.” The team tried different ways to modify the protocol until they achieved satisfactory results. “This method turned out to be very sensitive and very accurate,” says Dr. Yu, “It was a great academia-industry collaboration. We formed a great team.”
Advantages of NanoBiT® Technology for Detection of Mycotoxins
There are many advantages of using NanoBiT® technology for this biosensor to detect mycotoxin. First of all, the protocol is simple and fast. “It is homogeneous. You just mix everything together and it gives you a result. So there is less chance of making mistakes. And it’s very fast and reliable,” says Dr. Yu. The whole process from sample to results takes less than 30 minutes, much faster than other immunoassays that typically take 1–2 hours. Another advantage is the high sensitivity. Dr. Alsulami was astonished to find that the FNanoBiT assay could detect fumonisin B1 at concentrations as low as 0.079ng/ml. “When I determined the limit of detection and got that number, I was really surprised!” he says. This level of sensitivity cannot be achieved with existing immunoassays.
The Future of Food Testing
The success of FNanoBiT has opened the door to developing biosensors for detection of other mycotoxins. “Applying this very fast, easy to use homogeneous immunoassay using NanoBiT® technology for every single mycotoxin out there would be ideal,” says Dr. Yu. Dr. Alsulami, who has now accepted a faculty position at King Saud University in Saudi Arabia, will continue working with Promega to further develop this technology with the hope that it can become widely available.
Bioluminescent biosensors combined with smartphone technology could revolutionize the food testing industry. In the future, we may be able to detect luminescence signal generated by biosensors using just a smartphone camera. The development of faster, more convenient field-based food testing methods could potentially save lives. Much more work is needed for this to become reality, but with the help of bioluminescence, the future of food testing looks brighter than ever.
Learn about other exciting applications using NanoBiT® technology!