Detection and Control of Histamine-Producing Bacteria in Fish

Abstract

Histamine (or scombroid) fish poisoning the most frequently reported illness associated with consumption of fish despite efforts of its control. The lack of adequate control measures and unreliable detection method for histamine-producing bacteria (HPB) can in part be responsible for the high incidence of the disease. The aim of the studies was to address these concerns. Available detection methods were compared and related to histamine-production. Next, a DNA probe based on the histidine decarboxylase (hdc) gene was developed and applied to colony lift hybridization for enumeration of HPB from fish. Finally, the used of phosphate as a control of HPB was examined. The results demonstrated that the potentiometric, and PCR detection methods accurately detected high-HPB but did not detect the low histamine producing isolates. Although, the culture-based Nivens method, detected low histamine-producing bacteria, it resulted in 38% false positive responses. A hdc-probe mix from four HPB detected all 73 high-histamine producing bacteria in DNA dot-blot hybridization. However, six low and seventy-three non-HPB were not detected. Application of the hdc-probe mix in colony-lift hybridization resulted in more accurate quantification of HPB compared to the commonly used Niven’s method. Phosphate treatment of mahi-mahi samples significantly reduced histamine-production by increasing the surface pH of the fish muscle. The ability not only to detect but enumerate histamine-producing bacteria in fish is important for evaluating the potential risks and to develop adequate control strategies prior to formation of toxic levels of histamine.