New DNA test offers breakthrough support to European oysters

Published on
June 22, 2021
Xelect and Orkney Shellfish Hatchery have created DNA-based method of detecting the pathogen Bonamia in European flat oysters.

A new, non-destructive DNA-based method of detecting the pathogen Bonamia ostreae in European flat oysters has been jointly-developed by Scottish aquaculture company Orkney Shellfish Hatchery and genetics provider Xelect.

Bonamia ostreae is a major problem for many wild native oyster populations and is linked to the major decline in the bivalve’s abundance. But while Bonamia testing is widely available, the partners said this is typically “destructive,” with the oysters damaged or killed and limiting the ability of the hatcheries to identify and then utilize disease-free broodstock for larval production.

Through the DNA test, Orkney Shellfish Hatchery can now ensure the Bonamia-free status of each individual incoming native oyster broodstock, resulting in a much higher degree of hatchery biosecurity and wider options for broodstock sourcing.

Xelect used a tried-and-tested method known as a “Taqman Assay,” but adapted it to the specific challenge of testing for the presence of the pathogen from a filtered water sample – a technique called environmental DNA (eDNA) analysis.

Nik Sachlikidis from the Cadman Capital Group, which owns Orkney Shellfish Hatchery, said the test is “another demonstration” of the hatchery’s commitment to using science-backed technology to provide the highest possible standard of product.

“We know that our oysters are exceptional, and now we can also demonstrate that they’re disease-free too. We’re continually looking at new ways to improve our native oyster spat product, and to set new standards for industry best practice in this area. Xelect have done a great job of working hand-in-hand with our team to solve some key issues facing the native oyster hatcheries and ensuring our broodstock are Bonamia-free,” Sachlikidis said.

Xelect’s Paolo Ruggeri, who oversaw the analysis, explained that bivalves like the flat oyster filter large volumes of water every day, and in the process shed tiny amounts of their own DNA, and the DNA of any parasite they are carrying.

“Using a highly sensitive DNA test, we can sample the waters the oysters live in to identify the presence of the pathogen. It’s an extremely cost-effective and humane approach, and the oysters don’t even need to leave their hatchery,” he said.

Photo courtesy of Xelect

Contributing Editor reporting from London, UK

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