牛乳中嗜冷菌PCR检测

论文编号:SW224  论文字数:10767,页数:18

摘要：随着生活的改善，消费者对乳制品质量要求的日渐提高，乳制品中微生物的污染程度成为影响市场竞争的关键因素。牛乳在贮存过程中，大多数嗜冷菌会产生耐受巴氏消毒甚至超高温（UHT）瞬时灭菌处理的蛋白酶和脂肪酶，分解牛乳中的蛋白质和脂肪。这些分解产物将导致乳制品风味改变、品质降低，保质期缩短，严重影响乳制品的质量，并最终危害消费者的健康。要减少嗜冷菌的危害，早期对牛奶原料中嗜冷菌的检测和控制是关键。
 论文工作围绕牛乳中嗜冷菌展开。采用牛肉膏蛋白胨培养基及特定的CVT选择性培养基分离牛乳中的嗜冷菌，通过形态学特征观察、革兰氏染色和常见细菌生理生化试验（H2O2试验、M.R试验、V-P试验等）鉴定菌株，推断其菌属。结果表明，为杆菌属和球菌属。根据菌属基因序列设计PCR引物，提取基因组DNA进行PCR快速检测，然后进行测序比对。我们选择了牛乳中分离出的嗜冷菌中的9株进行测序比对，其中6株为嗜冷杆菌。
关键词：牛乳；嗜冷菌；PCR检测

Abstract: Along with life improvement, dairy products quality is enhanced day after day. In the dairy products, microorganism's pollution becomes the key factor that affects the market competition. When milk is stored, the mass of Psychrophile can generate protease and lipase which can withstand pasteurization, let alone Ultra-high temperature (UHT) instantaneous sterilization. They decompose protein and fat. These decomposition products will cause the dairy products change relish, drop quality, shorten guarantee period, thus having serious impact on product quality and harming consumer's health finally. To reduce the harm caused by Psychrophile, examining and controlling the raw milk in early stage is the point.
 The article encircles Psychrophile in the cow's milk to launch. We used the cow meat extract and protein peptone culture medium and CVT specific culture medium to isolate Psychrophile from the cow's milk, and appraised bacterium strain by morphological character observation, Gram’s staining and common bacterium physiology biochemistry experiment(H2O2　experiment, M.R experiment, V-P determination, etc.), then inferred bacteria genus. The results indicate that they are bacillus and coccus. According to the bacteria gene sequence, we also designed PCR primer, and collected genome DNA for PCR rapid test, then tested and contrasted sequence. We chose 9 strains of Psychrophile that were isolated from milk for testing and contrasting sequence. There have 6 strains of Psychrobacter. 
Keywords: Milk; Psychrophile; PCR Test

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