Mobile phone app could screen shellfish, say scientists

You can do just about anything with your mobile phone these days, but checking whether your oysters are safe to eat has not been one of their many functions.

This could change though after scientists developed a fluorescent probe that can screen shellfish to check if they are safe to eat. Team leader Michael Burkart said the breakthrough held "tremendous potential" for a food quality screening mobile phone app.

The microscopic tool pinpoints dinoflagellates - organisms commonly found in seawater. Some can be toxic and are associated with harmful algae and bacteria accumulation, which can lead to toxins transferring into shellfish tissue, posing a major threat to food safety.  

Although it has been considered that symbiotic bacteria are important in the biosynthesis of toxins from dinoflagellates, this toxin-bacteria interaction has only now been established, according to research published in the Royal Society of Chemistry journal Chemical Communications.  Burkart and colleagues at the University of California, San Diego, have used their findings to develop a fluorescence microscopy tool to screen shellfish for toxin producing dinoflagellates.

Burkart's team fluorescently-labelled a protein that is taken up by the marine cells responsible for biosynthesising the toxin, okadaic acid. In vivo studies clearly show that the samples producing the toxin glow fluorescent blue under the microscope. The samples that provide a positive response to the probe also show signs of symbiotic bacteria in the cell walls, confirming the toxin-bacteria association.

Using this information, the scientists were able to select mussels that contain live toxin producing dinoflagellates at different stages of infection by counting the number of cells that fluoresce. Imaging shellfish during dinoflagellate infection detects okadaic acid much quicker than present techniques, which can only detect the dinoflagellates once they have been fully absorbed into the shellfish tissue.   

Jon Clardy, a researcher at the Harvard Medical School in Cambridge, United States, said the result could be "a potentially useful surveillance tool for public health". He was surprised to find out that the bacteria are somehow involved in the biosynthesis of okadaic acid and possibly related to dinoflagellate toxins: "The biosynthesis of these compounds has been untouchable because of the enormous size of dinoflagellate genomes, which are much larger than human genomes, and the lack of genetic systems, which has frustrated commonly used approaches."

Burkhart says that if this method can be applied to an automated system then it could prove to be a useful screening tool for industry. Looking further to the future he said: "One could imagine a mobile phone application that would let you see if your crop or plate of oysters is safe for consumption. There is a tremendous potential in visual methods for food quality screening and its merge with the modern digital devices and networks.'

References

Metabolic probes for imaging endosymbiotic bacteria within toxic Dinoflagellates
C P Reyes, J J La Clair, M D Burkart, Chemical Communications, 2010
DOI: 10/10.39/C0CC02876B