New technology reduces shellfish poisoning risk

New early warning technology advances in the United States and Europe are set to reduce the risk of shellfish poisoning and save the aquaculture industry money.

Chemists at the University of California-San Diego have developed a marker that flags toxin-producing organisms in shellfish by setting up a system to add a fluorescent tag to an enzyme that makes one kind of toxin, okadaic acid. By handing the tag to the molecule that turns the enzyme on, it ensures that only the parts of cells that are capable of making the toxin would glow.

Oysters and mussels accumulate single-celled marine creatures called dinoflagellates in their digestive systems as they filter seawater for food, which are mostly harmless but sometimes produce toxins that accumulate and can cause humans to get sick.

According to the U.S. chemists, the harmful specks glow brightly on the surface of dinoflagellates, incubated with both the marker and symbiotic bacteria, and the toxin accumulates in the culture. The new marker showed mussel guts glowing with toxin-producing dinoflagellates even before the poison transferred to the mussel tissue itself. If the chemists add antibiotics to the mix, the lights go off, and toxin production ceases.

Funded by the National Institute of General Medical Science and the American Chemical Society, the project method uses a fluroscence microscope to spot the tagged cells. But the scientists are working on developing technology to make the tag easy to detect with a handheld device.

A second test developed at Queen’s Institute for Agri-Food and Land Use in Ireland reduces the testing time to monitor harmful toxins in shellfish.

The common mouse bioassay test can take up to two days to verify the presence of toxins in shellfish. But the Irish researchers claim that their new test takes just 30 minutes using new biosensor technology and provides a much more reliable result.

The test functions by using unique “detector proteins” to seek out minute amounts of toxins present in mussels, oysters, cockles and scallops.

“The test will not only make shellfish safer to eat, but it will also have a significant impact on global aquaculture industries as they struggle to deal with the rising problems of toxins caused by climate change,” said Professor Chris Elliott, director of the Institute of Agri-Food and Land Use at Queen’s School of Biological Sciences.

The test is set to expand the food-safety test portfolio at UK-based firm Neogen Europe, which has signed a substantial contract with Queen’s to commercialize the idea.

Interest has also arrived from overseas, with the research at Queen’s boosted by a USD 500,000 grant from the U.S. Food and Drug Administration. According to Queen’s, the FDA is keen to further develop the test in the United States to drastically cut the time it takes to get the catch from fishing nets to supermarket shelves with tests in laboratories and on boats as soon as the shellfish are caught.

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