Polymerase chain reaction for the detection of histamine-producing bacteria isolated from Taiwanese foods

It is important to develop rapid methods to detect the presence of histamine producers. In this study, the polymerase chain reaction (PCR) assay yielded a 367-bp DNA amplification fragment from histidine decarboxylase (hdc) of gram-positive bacteria using JV16HC/JV17HC primer, and 534-bp and 709-bp DNA amplification fragments from histidine decarboxylase of gram-negative bacteria using 106/107and hde-f/hde-r primers, respectively. Seven gram-positive histamine-producing strains and 15 gram-negative histamine-producing strains isolated from Taiwanese foods successfully produced the PCR amplification products. The minimum levels of detection of Enterobacter aerogenes or Raoultella ornithinolytica after the PCR amplification using hde-f/hde-r and 106/107 primerswere 10^5 and 10^6 CFU/mL in TSB broth, and 10^6 and 10^7 CFU/g in marlin homogenares, respectively. The hdc amplification using hdc-I/hdc-r primer was detected 2 h earlier than the HPLC detection of histamine in TSBH broth or marlin homogenates inoculated E. aerogenes or R. ornithinolyt icu. However, the detection of hdc amplification using the 106/107 primer and that of histamine by HPLC occurred at the same sampling time. Therefore, the PCR method could be easily used to detect potential histamine-producing bacteria in foods.