TABLE 3.
Comparison of standard MPN to QPCR-MPN analysis of PHP oyster samples
| Oyster lot | Treatmenta | Avg (±SD) log MPN/gb
|
|
|---|---|---|---|
| FDA MPN | QPCR MPN | ||
| 1 | Pre-PHP | 2.7 ± 1.5 | 3.2 ± 0.3 |
| 2 | Pre-PHP | 4.4 ± 0.4 | 4.8 ± 0.2 |
| 3 | Pre-PHP | 4.1 ± 1.0 | 4.3 ± 0.5 |
| 1 | PHP 1D | 0.9 ± 0.5 | 1.7 ± 1.1 |
| 2 | PHP 1D | 1.9 ± 0.6 | 2.3 ± 0.3 |
| 3 | PHP 1D | 3.7 ± 0.3 | 3.8 ± 0.2 |
| 1 | PHP 21D | 1.5 ± 0.4 | 2.0 ± 0.1 |
| 2 | PHP 21D | 0.6 ± 0.3 | 0.6 ± 0.3 |
| 3 | PHP 21D | 0.5 ± 0.0 | 0.5 ± 0.0 |
| 4 | PHP 21D | 1.1 ± 0.2 | 0.9 ± 0.3 |
a
Individual oyster lots (n = 4) were heat abused by incubation at 26°C for 24 h (pre-PHP), followed by processing with ultralow freezing in liquid nitrogen and frozen storage at −10°C for 1 (PHP 1D) or 21 (PHP 21D) days following PHP.
b
For each lot, oysters (n = 12) were sampled in triplicate, and log MPN/g values were determined by the standard FDA bacteriological analytical manual method (FDA MPN) or by MPN using QCPR confirmation with SYBR green I (QPCR-MPN), as described in the text. Lots 1 to 3 were examined before and after PHP, and lot 4 was examined only at 21 days after PHP.