传统发酵鱼露的微生物群落结构分析及降生物胺菌特性研究

Biogenic amines(BA) are found in various fermented foods and excessive intake will be harmful to human health. As a traditional Chinese fermented food, fish sauce is made from salted low value fish and shrimp by natural open fermentation. It is popular by consumers for its nutritious and special flavor, so fish sauce sales and sale range are increasing now. But it has been paid more attention to its biogenic amines. However, it is not very clear for the microbial community in fish sauce fermentation process, and also its relation to biogenic amines until now. These problems are worth our high concerns. Based on our previous work, we sample traditional Chinese fish sauce from different regions to further analyze the microbial community, change and predominant strains using high-throughput sequencing technology. Connecting with the above research results and biogenic amines in fish sauce, we expect to find the relations between biogenic amines and the corresponding microorganisms, and then screening the aimed BA-producing strains and the aimed BA-degrading strains from dominant microorganisms, respectively. After that, we will study the characteristics of the aimed BA-degrading strains and theirs food safety. Besides that, we will also study the interaction the BA-producing strains and the biogenic-amine-degrading strains and biogenic amine change in simulated fish sauce. The capability of BA-degrading strains in fish sauce fermentation and the sensory traits will be evaluated. At last, we will research the biogenic amine degrading method(s) of the BA-degrading strains. These expected results will not only enrich fermentation mechanism of fish sauce and be contribute to develop the innovation of technologies in degrading the biogenic amines in fish sauce, but also give guidance to the improvement of the safety of other fermented foods.

生物胺广泛存在于传统发酵食品中，过量摄入危害人体健康。传统鱼露由低值鱼、虾和食盐混合自然发酵而成。因其营养丰富、风味独特，销量和销售范围日益扩大。但其中生物胺含量较高，亟待解决。然而目前鱼露发酵的微生物群落及其与生物胺的关系等还不十分清楚，在一定程度上阻碍了生物胺问题的解决进程。本项目基于前期研究，多地采集鱼露，采用高通量测序等技术，解析我国传统鱼露发酵过程中微生物群落结构、演替及优势菌；理清生物胺与优势菌的关系，筛选出目标产生物胺菌（简称目标产胺菌）和目标降生物胺菌（简称目标降胺菌）；研究目标降胺菌的特性和安全性；研究目标降胺菌和目标产胺菌在模拟鱼露发酵期间的互作及生物胺的消长，并评价目标降胺菌对传统鱼露生物胺及品质的影响；最后探讨目标降胺菌降生物胺的作用方式。本项目研究成果不仅能丰富传统鱼露的发酵理论，还为研发鱼露中生物胺控制技术提供理论依据，也为解决其他发酵食品中生物胺问题提供参考。

人体过量摄入生物胺会产生有害反应。传统鱼露中不可避免地含有生物胺。本项目对福建福州、山东威海和山东青岛的鱼露样品研究发现，各地鱼露微生物群落组成差异较大，福州鱼露的细菌群落归属6个门119个菌属，威海鱼露的有7个门157个属，青岛鱼露有6个门22个菌属，其中三者共有变形菌门（Proteobacteria）、厚壁菌门（Firmicutes），放线菌门（Actinobacteria）和拟杆菌门（Bacteroidetes）；威海鱼露真菌群落归于4个门98个属，福州鱼露有4个门151个属，青岛鱼露有6个门22个属。威海鱼露和福州鱼露中四联球菌属（Tetragenococcus）和嗜冷杆菌属（Psychrobacter）丰度最大；青岛鱼露中嗜冷杆菌属（Psychrobacter）和假单胞菌属（Pseudomonas）丰度排前。各样品生物胺含量不等；同一产家鱼露的生物胺含量随发酵过程呈波动趋势，这与其微生物群落组成及微生物代谢活动密切相关。分离到17株各具特点的生物胺产生菌。分离到7株高效生物胺降解菌，并重点研究其中的Pichia kudriavzevii MZ5、Millerozyma farinose A3和Enterococcus faecium R7的生长特性、降生物胺的特性和安全性。三株菌消减生物胺的方式均是生物降解，研究了粗酶的特性，降解酶是胞内细胞膜上。接种目标降胺菌发酵鱼露能有效减少生物胺含量，以组胺为例，在发酵180 d时，相比于对照组，M. farinose A3组、E. faecium R7组和复合组的组胺含量分别下降了50.0%、26.35%和63.38%；提升了鱼露的风味和营养。本项目研究结果进一步丰富了鱼露的发酵理论；获得的目标降胺菌今后有望将其开发成新型鱼露发酵剂的核心菌，有利于提升鱼露的食用安全性，也为解决其他发酵食品生物胺问题提供参考。