Development of a Method for Detecting Based on the Quantification of by Chip-Based Digital PCR.

which produces the paralytic shellfish toxin (PST) saxitoxin (STX), is one of the causative species of paralytic shellfish poisoning outbreaks in coastal areas of Korea. In this study, we developed a chip-based digital PCR (dPCR) method for detection and tested it for monitoring in Jinhae-Masan Bay. Using the sequence of an strain isolated in 2017, species-specific primers targeting (a STX biosynthesis-related gene) were designed and used in a dPCR, detecting 2.0 ± 0.24 gene copies per cell of . Cell abundance in field samples, estimated by a chip-based dPCR, was compared with the PST content, and measured using a mouse bioassay. A comparison with shellfish PST concentrations indicated that cell concentrations above 500 cells L, as measured using the dPCR assay, may cause shellfish PST concentrations to exceed the allowed limits for PSTs. Concordance rates between dPCR and PST results were 62.5% overall in 2018-2021, reaching a maximum of 91.7% in 2018-2019. The sensitivity of the dPCR assay was higher than that of microscopy and -based qPCRs. Absolute quantification by chip-based dPCRs targeting in . exhibits potential as a complementary approach to mouse bioassay PST monitoring for the prevention of toxic blooms.