Determining the Sensitivity of the LAMPAssay
The sensitivity of the LAMP assay was evaluated on the basis of pork genomic DNA that was serially diluted to final
concentrations ranging from 50 to 5×10−7 ng/μL. Each reaction
contained 1 μL of diluted DNA sample as a template. The
detection limit of the LAMP assay for pork DNA was found to
be 0.5 pg/reaction (Fig. 3).
We then mixed pork DNA into beef or mutton DNA to
produce nominal concentrations of 50, 10, 1, 0.1, 0.01, and
0 % to mimic meat adulteration. A total of 50 ng of genomic
DNAwas used in each reaction, and a mixture of 0.01 % pork
in beef could be detected (Fig. 4). The same result was found
for pork adulteration in mutton (data not shown).
Compared with other previous studies, this limit of detection
represents greater sensitivity than Karabasanavar’s 10 pg
(Karabasanavar et al. 2014) detected via species-specific PCR
and is similar to Martin’s (Martin et al. 2009) real-time PCR
method, which had a detection limit of 0.1 pg. Real-time PCR
is now recognized as the most sensitive method to detect
nucleic acid molecules, and our LAMP assay has a similar
sensitivity. Furthermore, we can detect 0.01 % pork in adulterated
sample mixtures, equivalent to 0.1 g of pork adulteration
in 1 kg of meat. The sensitivity was thereby satisfactory in
detecting adulterated meat.