TABLE 3.
Real-time PCR-based quantification method of L. sakei compared to traditional plate counta
| Sample no. | Type of sample | MRS count (mean ± SE)b | % of L. sakei ± SEc | L. sakei count (mean ± SE)b | L. sakei count estimated by real-time PCR (mean ± SE)b |
|---|---|---|---|---|---|
| S1 | Fermented sausage | 7.69 ± 0.02 | 100 ± 0.0 | 7.69 ± 0.00 | 7.08 ± 0.05 |
| S2 | Fermented sausage | 7.52 ± 0.06 | 75 ± 8.8 | 6.77 ± 0.61 | 6.24 ± 0.22 |
| S3 | Fermented sausage | 8.79 ± 0.08 | 64 ± 9.6 | 7.99 ± 0.79 | 7.39 ± 0.15 |
| S4 | Fermented sausage | 8.43 ± 0.04 | 100 ± 0.0 | 8.43 ± 0.00 | 8.07 ± 0.03 |
| S5 | Fermented sausage | 8.32 ± 0.06 | 48 ± 9.9 | 8.00 ± 0.83 | 7.85 ± 0.09 |
| S6 | Fermented sausage | 7.52 ± 0.07 | 0 ± 0.0 | ND | ND |
| S7 | Fermented sausage | 9.20 ± 0.02 | 12 ± 3.2 | 7.18 ± 0.26 | 6.84 ± 0.06 |
| M1 | Meat batter | 4.60 ± 0.11 | 0 ± 0.0 | ND | ND |
| M2 | Meat batter | 6.10 ± 0.05 | 68 ± 9.7 | 5.93 ± 0.59 | 5.41 ± 0.01 |
| M3 | Meat batter | 4.87 ± 0.01 | 0 ± 0.0 | ND | ND |
| M4 | Meat batter | 3.62 ± 0.08 | 60 ± 9.2 | 3.40 ± 0.34 | D |
a
Samples were purified by pre-PCR treatment with Chelex 100. Counts are expressed in log10 CFU/g.
b
The values are means of triplicates ± standard errors.
c
Percentages of L. sakei were calculated by the identification of a minimum of 25 colonies from MRS plates, and the standard errors were calculated from a binomial sampling distribution. ND, none detected; D, detected below the quantification limit.