微生物发酵对淡水鱼活性脂质的影响及分子机制

The content and composition of fatty acids are important indicators for evaluating the nutritional value of foods. Microbial fermentation is an effective technique for processing and utilization of freshwater fish. Solid-state fermented fish usually contains abundant unsaturated fatty acids with important physiological activity, microorganism, as well as enzymes related to lipid metabolism. However, it is unclear for the role and mechanisms of these microorganism and endogenous enzymes in lipid changes during solid-state fermentation of freshwater fish. In the present study, the freshwater fish being used as material, the changes of lipids during fermentation and their relationship with nutritional quality of fish will be investigated, and the factors affecting on fatty acid changes of fermented fish will be explored. Using dominant strains isolated from solid-state fermented fish, the ability and metabolic pathways of selected strains and fish endogenous enzymes to biotransform, synthesis and oxidation of unsaturated fatty acids as well as their interact with each other will be emphasisly investigated. The action and its mechanism of strains and endogenous enzymes in fatty acid changes in solid-state fermented fish will be clarified. This research will help to reveal the relationship between microbial metabolism and fatty acid change in solid-state fermented fish. It is of great academic value for elucidating the change mechanism of important nutrient in complex food systems. And it is also of great significance for enriching the theory of bio-fermentation technology of freshwater fish and regulation of nutritional quality of fermented fish products.

脂肪酸含量和组成是评价食品营养价值的重要指标。生物发酵是淡水鱼加工利用的一种重要技术手段。固态发酵鱼中含有大量具有重要营养功能的不饱和脂肪酸、微生物以及脂质代谢酶类，但目前对于发酵微生物和鱼肉内源酶在固态发酵鱼脂质变化中的作用和机制仍不清楚。本研究以淡水鱼为对象，研究鱼肉发酵过程中脂质变化规律、影响因素及与鱼肉营养品质的关系；应用固态发酵鱼分离获得的优势微生物菌株，重点研究微生物菌株和鱼肉內源酶生物转化、合成、氧化不饱和脂肪酸的能力和途径及相互关系，阐明微生物和內源酶在固态发酵鱼脂肪酸变化中的作用和机制。本研究有助于揭示微生物代谢与固态发酵鱼脂肪酸变化间的关系，对阐明复杂食品体系中重要营养素变化机理具有重要学术价值，同时对丰富淡水鱼生物发酵加工技术理论和发酵鱼营养品质调控具有非常重要的意义。

生物发酵是淡水鱼加工利用的一种重要技术手段。脂肪变化与发酵鱼肉制品营养品质和风味形成密切相关。本项目针对传统固态发酵鱼脂质变化机制的相关科学问题，重点研究了鱼肉发酵过程中脂质组成与脂肪酸分布、脂质降解与氧化及鱼肉内源酶和发酵微生物在脂质变化中的作用与机制；探明了鱼肉发酵过程中中性脂肪、游离脂肪酸、磷脂等脂质的变化规律及接种微生物菌株与发酵工艺条件的影响，明确了磷脂是游离脂肪酸中不饱和脂肪酸尤其是PUFA的主要来源；从内源脂肪酶活性变化分析与构建抑菌酸化模拟体系两方面确定了不同内源酶与微生物在发酵鱼脂质降解和氧化中的相对作用，明确了鱼肉内源脂肪酶在脂质水解方面起主要作用，发酵微生物在脂质氧化方面起主导作用；在此基础上研究了不同微生物菌株及其相互作用对脂质变化的影响，发现木糖葡萄球菌对脂质降解贡献较大，而植物乳杆菌脂解能力较小但能促进脂肪酸氧化，但在共培养条件下Lp-120对Sx-135和Sc-31水解和氧化脂质的能力均有抑制作用；揭示了酸鱼发酵过程中微生物群落动态变化及参与脂肪酸代谢的重要途经，发现脂肪酸氧化主要注释到β氧化和脂氧合酶途经，而未注释到完整的乙酰辅酶A 途径，其中Staphylococcus能够参与完整的β氧化和脂氧合酶途径。本项目研究有助于阐明微生物代谢与发酵鱼脂肪酸变化间的关系，揭示鱼肉发酵过程中脂质变化的分子机制，同时对发酵鱼营养和风味品质调控提供重要的理论指导。