Isolation of Histamine-Forming Bacteria and Their Physicochemical Properties Analysis of Pacific Saury （Cololabis saira）

Abstract:

This study was conducted to isolate and identify histamine-forming bacteria （HFB） in Pacific saury （Cololabis saira） with the aid of different selective mediums as well as the physicochemical properties analysis. Meanwhile，the impact of different temperature and pH value on the histamine-forming capacity of the isolated bacteria were also investigated. The results showed that five HFB were isolated and identified from Pacific saury，which were named as strain 1，strain 2，strain 3，strain 4 and strain 5. They were likely belong to Hafnia，Shigella，Proteus hauser，Serratia and Pseudomonas，respectively. All the HFB could produce histamine in the range of 4—36 ℃ and the pH 4.5—8.5. The optimum temperature for strain 1，strain 2，strain 3，strain 4 and strain 5 to produce histamine were 20，36，36，20 and 25 ℃，respectively，while the optimum pH value were 8.5，7.5，6.5，6.5 and 7.5，respectively. Under the optimum conditions，the histamine-forming capacity of all the HFB was over 20 mg/mL. Although low temperature （4 ℃） and acidic environment significantly decreased the histamine-forming capacity of the HFB，the histamine concentration could maintain a relatively high level. These results provide a theoretical basis for controlling the level of HFB in Pacific saury.