Abstract
A coliform flora analysis method using real-time polymerase chain reaction (PCR) was developed. The amplified region targeted was lacZ, encoding β-galactosidase. Forty-two species belonging to 16 genera of coliform bacteria were successfully detected. Specific primers were designed to detect the genus Klebsiella/Enterobacter and the genus Citrobacter, allowing for the discrimination of coliform bacteria into 3 groups. Quantification of bacterial numbers ranged from 103 to 106 cfu per PCR reaction vessel. Differences in flora between vegetables and meat, and among various factory locations, were able to be detected. Finally, sources of contamination were investigated in a real food factory. Coliform bacteria were detected in 23 out of a total of 32 samples. As a result of cluster analysis, 4 potential sources of contamination during the manufacturing process were proposed for the 2 products. Analysis of the flora was completed in approximately 5 hours; thus, a rapid contamination source search system has been developed.
