鲭鱼中组胺降解酶产生菌的分离筛选和基本酶学性质研究

鲭鱼亚目的海洋鱼类在捕获后易产生组胺，导致鲭鱼中毒．为研究组胺消长与微生物的关系，通过平板分离和摇瓶发酵，以荧光光度法测定酶活力，从鲭鱼（Pneumatophorus japonicus）皮肉、内脏和腮中分离筛选组胺降解菌，并对所产组胺降解酶的酶学性质进行研究和分析．结果表明：自内脏中分离筛选到一株组胺降解酶活力较高的革兰氏阴性杆菌，从生长产酶曲线推测该酶为初级代谢产物．该酶反应的最适温度为35℃，最适pH为7．2．在pH6．0～8．0和温度20～35℃范围内有较好的稳定性．Mn^2＋、Ca^2＋、Na^-、Mg^2＋、K^＋等金属离子存在时酶活力增加。Zn^2＋、Al^3＋、Fe^3＋、Fe^2＋、Cu^2＋等金属离子存在时，酶活力下降，在EDTA存在条件下酶活力完全丧失．对其动力学研究表明，在甘氨酸-NaOH缓冲反应体系中，最大反应速度Vmax=156．25U·mL^-1，米氏常数Km=0．22mg·mL^-1．组胺降解菌国内还朱见报道，研究结果对进一步研究水产品组胺生物控制技术具有重要意义．

Isolation of Histamine-degrading Enzyme Producing Bacteria from Mackerel and Characteration of Enzyme Concerned

Marine fishes,scombroid species in paticular,are susceptible to producing histamine during processing and storage,as has been reported in incidents of scombroid fish poisoning.To understand the relationship between the producing and degrading of histamine and the microorganism concerned in fish,the bacterials with the capacity of producing histamine-degrading enzyme are screened from skin,flesh,entrails and gills of mackerel(Pneumatophorus japonicus) by plate and shaking flask culture,followed with testing the enzyme activity by pectrofluorimetry method.A gram-negative rod bacterium producing histamine-degrading enzyme is isolated from entrails of mackerel.The enzyme is presumed to be primary metabolite according to the growth and enzyme production curves.The optimum pH and temperature of the crude enzyme activity to histamine is found to be 7.2 and 35 ℃ respectively,and a high stability of the enzyme is observed at 20-35 ℃ and pH 6.0~8.0.It is activated by 5 mmol.L-1of ions such as Mn2+,Ca2+,Na-,Mg2+,K+,but inhibited by Zn2+,Al3+,Fe3+,Fe2+,Cu2+,and completely inhibited by EDTA.The results of kinetic studies show that the kinetic parameter Km of the enzyme was 0.22 mg.mL-1,and the Vmax of the enzyme is 156.25 U.mL-1.This paoer presents the first domestic report on histamine-degrading enzyme producing bacteria,and the study is believed to be important to seek biological control of histamine in food processing in the future.