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摘 要：采用变性梯度凝胶电泳（polymerase chain reaction-amplification and denaturing gradient gel electrophorsis，PCR-DGGE）技术，分析在4 ℃冷藏条件下鲫鱼肌肉和鱼鳃的菌相组成及变化，并利用不同浓度抗菌素溶液对鲫鱼鱼肉进行浸泡处理，以未处理作为对照，分别测定其菌落总数、挥发性盐基氮（total volatile basic nitrogen，TVB-N）和pH值等指标，评价细菌素对鲫鱼冷藏保鲜效果。结果表明：鲫鱼贮藏过程中的微生物菌相变化具有多样性，确定气单胞菌属（Aeromonas sp.）、荧光假单胞菌 （Pseudomonas fluorescens）、不动杆菌属（Acinetobacter sp.）和热杀索丝菌属（Brochothrix thermosphacta）为鲫鱼鱼肉的优势腐败菌，而棉子糖乳球菌属（Lactococcus raffinolactis）、从毛单胞菌属（Comamonas sp.）和气单胞菌属（Aeromonas sp.）为鲫鱼鱼鳃的优势腐败菌，表明鱼肉和鱼鳃在贮藏过程中，导致腐败的优势腐败菌具有一定差异性。同时，不同浓度的细菌素对鲫鱼均有明显的防腐保鲜作用，有效抑制了鲫鱼菌落总数、TVB-N值的增长、pH值的升高以及硫代巴比妥酸(Thiobarbituric acid reactive substance, TBA)增长。25978
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毕业论文关键词：鲫鱼；腐败微生物；变性梯度凝胶电泳技术；抗菌素；保鲜
Changes in Microbial Community Composition of Crucian Carp during Storage and Preservation of Crucian Carp
Abstract: The microbial community structure of crucian carp was studied by polymerase chain reaction-amplification and denaturing gradient gel electrophorsis (PCR-DGGE) during storage at 4℃. Meanwhile, antimicrobial lipopeptide was used for the preservation of crucian carp. The antimicrobial effect of applied lipopeptide was evaluated through the determination of total bacterial counts, total volatile basic nitrogen (TVB-N), pH and TBA. The results showed that the microbial community of crucian carp was perse at the end of storage. Specifically, Pseudomonas sp., Shewanella sp., Aeromonas sp. and Acinetobacter sp. were the dominant spoilage microorganisms in the flesh of fish, while Lactococcus raffinolactis, Cetobacterium, Pseudomonas sp. and Aeromonas sp were the main spoilage microorganisms in the gill. These results also indicated that although the compositions of microbial community in flesh and gill of crucian carp were different, they showed a similar trend during storage. On the other hand, the crude extract from Lactobacillus plantarum 163 broth at different concentrations significantly inhibited the increase of total bacterial counts, TVB-N, pH and TBA. All these results demonstrated that the crude extract from Lactobacillus plantarum 163 broth can significantly inhibit the growth of spoilage microorganisms in crucian carp, thus being a promising preservative.
Key words: crucian carp; spoilage bacterial; polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE); antimicrobial lipopeptide; preservation.
目录
摘 要 3
关键词 3
Abstract 3
Key words. 3
引言 3
1. 材料与方法 4
1.1 材料与试剂 4
1.2 仪器与设备 4
1.3 方法 4
1.3.1 菌落总数的测定 4
1.3.2 挥发性盐基氮（total volatile basic nitrogen， TVB-N）和pH值的测定 4
1.3.3 提取DNA的样品处理 5
1.3.4 总DNA的提取 5
1.3.5 PCR扩增 5
1.3.6 细菌DGGE分析 5
1.3.7 条带回收及测序 5
1.3.8 细菌素在鲫鱼中保鲜应用 5
1.3.8.1 Nisin标准曲线的测定 5
1.3.8.2 细菌素粗提物的制备 6