Development of rapid real-time PCR and most-probable-number real-time PCR assays to quantify enterotoxigenic strains of the species in the Bacillus cereus group.
Members of the Bacillus cereus group may produce diarrheal enterotoxins and could be potential hazards if they enter the food chain. Therefore, a method capable of detecting all the species in the B. cereus group rather than B. cereus alone is important. We selected nhe as the target and developed a real-time PCR assay to quantify enterotoxigenic strains of the B. cereus group. The real-time PCR assay was evaluated with 60 B. cereus group strains and 28 others. The assay was also used to construct calibration curves for different food matrices and feces. The assay has an excellent quantification capacity, as proved by its linearity (R2 > 0.993), wide dynamic quantification range (10(2) to 10(7) CFU/g for cooked rice and chicken, 10(3) to 10(7) CFU/ml for milk, and 10(4) to 10(7) CFU/g for feces), and adequate relative accuracy (85.5 to 101.1%). For the low-level contaminations, a most-probable-number real-time PCR assay was developed that could detect as low as 10(0) CFU/ml. Both assays were tested with real food samples and shown to beconsiderably appropriate for B. cereus group detection and quantification.
Yang
I-Chen
IC
Institute of Microbiology and Biochemistry, National Taiwan University, 1, Sec. 4, Roosevelt Road, Taipei, Taiwan, Republic of China.
Shih
Daniel Yang-Chih
DY
Wang
Jan-Yi
JY
Pani
Tzu-Ming
TM
D001409:Bacillus cereus / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism; D015169:Colony Count, Microbial / Q000379:methods; D004269:DNA, Bacterial / Q000737:chemistry; D004768:Enterotoxins / Q000096:biosynthesis* / Q000302:isolation & purification; D005243:Feces / Q000382:microbiology; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D011110:Polymorphism, Genetic; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D013045:Species Specificity
D004269:DNA, Bacterial; D004768:Enterotoxins