Table 8.

Influence of preenrichment incubation time and bacterial population in the amplification of PCR product specific to B. cereus

Sample or parameterPreenrichment incubation in nutrient broth (h)PCR band amplified when initial inoculum level was in the rangea or CFU per g of cooked-rice homogenateb:
2.4 × 1042.4 × 1032.4 × 1022.4 × 1012.40.240
Food homogenate0
6+++
15++++++
Population02.4 × 1042.4 × 1032.4 × 1022.4 × 1012.40.240
69.0 × 1064.6 × 1054.0 × 1049.7 × 1031.5 × 1032.0 × 1020
153.6 × 1072.3 × 1073.8 × 1074.3 × 1076.8 × 1077.7 × 1070
  • a −, 365-bp amplified product specific to B. cereus is not seen; +, 365-bp amplified product is seen.

  • b Since cooked rice was used as a sample, no culturable food microflora was observed, and the counts given are forB. cereus.