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Abstract

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 106/107 and hdc-f/hdc-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 hdc-f/hdc-r and 106/107 primers were 105 and 106 CFU/mL in TSB broth, and 106 and 107 CFU/g in marlin homogenates, respectively. The hdc amplification using hdc-f/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. ornithinolytica. 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.

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