RT Journal Article
SR Electronic
T1 MinION sequencing of seafood in Singapore reveals creatively labelled flatfishes, confused roe, pig DNA in squid balls, and phantom crustaceans
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 826032
DO 10.1101/826032
A1 Jonathan K. I. Ho
A1 Jayanthi Puniamoorthy
A1 Amrita Srivathsan
A1 Rudolf Meier
YR 2019
UL http://biorxiv.org/content/early/2019/10/31/826032.abstract
AB Food mislabelling is a growing world-wide problem that is increasingly addressed through the authentication of ingredients via techniques like mass spectrometry or DNA-sequencing. However, traditional DNA sequencing methods are slow, expensive, and require well-equipped laboratories. We here test whether these problems can be overcome through the use of Nanopore sequencing. We sequenced 92 single and 13 mixed-species samples bought in supermarkets and restaurants in Singapore which has a large and diverse seafood trade. We successfully obtained DNA barcodes for 94% and 100% of the single- and mixed-species products after correcting the numerous sequencing errors of MinION reads with a correction pipeline optimized for DNA barcodes. We find comparatively low levels of clear-cut mislabelling for single-species samples (7.6 %) while the rates are higher for mixed-species samples (38.5 %). These low rates are somewhat deceptive, however, because of the widespread use of vague common species names that do not allow for a precise assessment of the expected ingredients. With regard to the clearly mislabelled single-species products, higher-value products (e.g., prawn roe, wild-caught Atlantic salmon, halibut) are replaced with lower-value ingredients (e.g., fish roe, Pacific salmon, arrowtooth flounder) while more serious problems are observed for mixed-species samples. Cuttlefish and prawn balls repeatedly contained pig DNA and 100% of all mixed samples labelled as containing crustaceans (‘crab’, ‘prawn’, ‘lobster’) only yielded fish barcodes. We conclude that there is a need for more regular testing of seafood samples and suggest that due to speed and low-cost, MinION would be a good instrument for this purpose. We also emphasize the need for developing clearer labelling guidelines.