A tiny device to instantly detect pathogens that is being developed by researchers at Victoria University of Wellington could save the seafood industry millions of dollars a year and help reduce overfishing.
Professor Thomas Nann and Dr Renee Goreham, from Victoria’s School of Chemical and Physical Sciences, are working on a device that will use state-of-the-art aptamer technology to detect hazardous levels of food pathogens, specifically E. coli.
Professor Nann, who is also Director of the MacDiarmid Institute for Advanced Materials and Nanotechnology, says the device will target the extracellular vesicles (EVs) excreted by E.coli. These vesicles are nanometre-sized structures consisting of fluid enclosed by two layers of lipid molecules, which are released by cells.
“Once we’ve isolated the vesicles that are given off by E.coli bacteria—which is relatively easy to do with the nanotechnology we work with—we will then develop an aptamer [a molecule that binds to a specific compound] that will target them,” he says.
“It’s difficult to chase one single bacteria, because we cannot see it—at the moment we have to grow a sample in a lab over several days before we can actually identify if it contains bacteria. But bacteria excrete these vesicles all the time in great numbers, so if we chase the vesicles rather than the bacteria itself we can gather enough to detect it much more easily.”
He says the technique can be compared to finding a needle in a haystack. “The easiest way to find the needle is to take a magnet and run it over the haystack—we would be doing a similar thing, but instead of magnets we’d be using aptamers, which are a bit like chemical magnets. The vesicles we’ve identified would stick selectively to these aptamers.”
Dr Goreham says pathogen contamination is a huge problem in the food industry and can be costly—latest figures estimate the cost to New Zealand to be around $161.9 million a year.
“Fisheries are crying out for a fast, reliable and highly targeted sensor for foodborne pathogens. Currently, they have to monitor their whole manufacturing systems, which is very costly and not very reliable. Culturing a sample can take three days, so if that result comes three days after the initial contamination it could have spread throughout the entire factory in that time, meaning they have to shut down the whole operation,” she says. “We think that by detecting extracellular vesicles instead of the bacteria cells themselves, we will be able to identify pathogens on-site, which will make the process not only faster but much cheaper too.”
Dr Goreham says there will be other benefits too.
“Fisheries will save money by not having to dispose of a contaminated catch, recall the product or clean the entire processing plant, which they would otherwise have had to do after waiting several days for the presence of bacteria to be confirmed from a cultured sample,” says Dr Goreham. “As a consequence of not having to dispose of so much of the catch, more seafood will make it to market—that would mean larger profits for the fisheries as well as a likely reduction in overfishing.”
She says the technology has the potential to be applied to other food industries. “We are starting with fisheries, but once the prototype’s been developed and commercialised then the idea could be applied to industries such as milk or meat.”
Professor Nann and Dr Goreham are working with seafood company Sanford Ltd to test the technology. The pair is also hoping to work with AuramerBio, a specialist aptamer-producing company based in Wellington that was co-founded by Victoria University Associate Professor Justin Hodgkiss.
Professor Nann says the device could have a huge impact on the New Zealand economy. “We think it could enable the creation of high-value manufacturing jobs here, and also help lessen routine testing costs for the food industry, allow early in-house testing and reduce the large-scale wastage that comes with product recalls.”
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