绿色魏斯氏菌对低温肉制品的致腐效应及机制研究

As the specific spoilage bacteria of cooked meat products, Weissella viridescens can resists not only the cooking（68-85 °C）process in the factory, but also non-thermal decontamination methods, for instance, high hydrostatic pressure processing. During the whole storage time of cooked meat products, Weissella viridescens growth rapidly and gives rise to sour, slimes, swelling of the packages, green color and so on. Thereby, the market circulation and development of cooked meat products were severely restricted. This project intends to choose Weissella viridescens (isolated from spoilage cooked ham) as the research object. Bacteria spoiling effects and degradation process of meat source proteins will be evaluated in situ (inoculated to cooked ham) and in vitro condition, respectively. Specific spoilage metabolites, such as composition of slimes, swell bag gas and volatile organic compounds, etc. will be identified. The spoiling potential marker in the early stage of spoilage process will be found possibly. In vitro experiment, the degradation pathway of meat source proteins will be revealed and the key enzymes involved in the degradation process will also be determined. In addition, the whole genome of Weissella viridescens will be sequenced and analyzed, and the bioinformatics methods will be used to analyze and classify the genes related to bacterial extracellular enzymes. The possible pathways of specific spoilage metabolites will be obtained. Through these investigations related above, the spoiling mechanisms of Weissella viridescens to cooked ham will be revealed. These works will help us to fully understand the catabolic characteristics of spoilage bacteria, which provide theoretical knowledge for suggesting targeted control methods to effectively predict and extend the shelf-life of cooked meat products.

绿色魏斯氏菌（Weissella viridescens）作为低温肉制品中的特定腐败菌，既能耐受热加工蒸煮，又能抵御超高压等非热杀菌，在货架期内快速繁殖引起产品发酸、发黏、涨袋、绿变，严重制约低温肉制品市场流通和发展。本项目拟以该腐败菌为研究对象，通过接种和体外实验，分别针对其致腐效应和对肌肉蛋白质等肉源营养物质的降解过程开展研究。分析鉴定黏液组成、涨袋气体、挥发性有机物等特征性腐败代谢产物，寻求确立早期腐败标志物；体外验证腐败代谢产物的产生途径，确定参与降解过程的关键酶类。在此基础上，通过对绿色魏斯氏菌的全基因组测序和分析，运用生物信息学手段对细菌产酶相关功能基因进行解析和分类，绘制特征性腐败代谢产物可能的生成途径，揭示绿色魏斯氏菌引发低温肉制品腐败变质的作用机制。为更全面掌握腐败菌的分解代谢特性，从而提出靶向调控和干预手段，有效预测并延长肉制品货架期提供理论支撑。

绿色魏斯氏菌作为低温肉制品中的特定腐败菌，既能耐受热加工蒸煮，又能抵御超高压等非热杀菌，在货架期内快速繁殖引起产品发酸、发黏、涨袋、绿变，严重制约低温肉制品市场流通和发展。本项目拟以该腐败菌为研究对象，通过接种和体外实验，以及全基因组测序和分析，运用生物信息学手段对绿色魏斯氏菌引发低温肉制品腐败变质的作用机制进行研究。首先，通过体外实验发现，从低温火腿中分离鉴定得到的绿色魏斯氏菌NJ100 具有较强的生长能力，并且具有产酸、产气、产生H2O2、蛋白酶、纤维素酶以及较强的降解肌浆蛋白等的可以造成食品腐败的特性，因此它具有较强的腐败潜能；然后，通过接种实验发现，乙酸、乳酸乙酯、2-乙基-3-羟基-4-吡喃酮、二氧化碳等物质有可能作为指示绿色魏斯氏菌NJ100特征性腐败的潜在标志物；最后对绿色魏斯氏菌NJ100进行全基因组测序及通路注释发现，NJ100基因组编码了代谢乙酰乳酸、二乙酰、乙醛、丁二醇等腐败相关化合物的基因和途径。综上所述，本项目从表征和基因两个层面系统的研究了绿色魏斯氏菌致腐效应，为应对该菌的防控策略提供新的思路。本项目执行期以上工作发表学术论文1篇，培养研究生2人。