中华竹鼠源致病性大肠杆菌分离鉴定、耐药性及毒力基因检测

试验旨在查明贵州某竹鼠养殖场竹鼠死亡原因。通过细菌分离鉴定、形态学观察、生理生化特性定、16S rDNA基因序列分析及系统进化树构建等方法对分离菌种属进行确定,纸片扩散法进行药敏试验,PCR方法检测耐药基因,人工感染小鼠试验探究分离菌的致病性和PCR检测毒力基因。结果显示:经革兰氏染色镜检分离菌为革兰阴性短杆菌,其16S rDNA基因序列经测序及 BLAST比对,显示其与大肠埃希氏菌序列相似度达98.2%—100%。在系统发育树上与大肠杆菌聚为一枝。结合生理生化鉴定结果确定分离菌为大肠埃希氏菌。药敏试验结果显示,分离菌对氟苯尼考、头孢曲松、头孢氨苄等药物敏感、对四环素、多西环素、青霉素等药物表现耐药,4种耐药基因检测结果显示Intl 1(146 bp)、tetA(831 bp)2种耐药基因,与药敏表型相符。人工感染试验结果显示,该菌对小鼠有致病性。8种毒力基因检测分离菌携带papA(761 bp)、UidA(264 bp)、afa(251 bp)3种毒力因子。上述结果表明本实验分离到一株对四环素类耐药的竹鼠源大肠埃希氏菌,为该竹鼠养殖场的竹鼠疾病防治与合理用药提供了科学依据

三种竹鼠源致病性细菌混合感染病例的组织病理学变化分析

实验旨在研究竹鼠混合感染致病性大肠杆菌、致病性棒状杆菌和致病性绿色气球菌所引起的组织病理学变化。通过剖检、组织切片、苏木素—伊红（HE）染色及图像观察分析法观察混合感染3种致病性细菌的组织器官的病理及组织病理学变化。结果显示：患病竹鼠下牙脱落，被毛杂乱无光泽，后发现心包有严重无色透明液体、心脏质地柔软凹陷、可见淤血，肝脏表面光滑分布红色细血丝、有明显出血点，肺脏表面可见深红色斑块；脾脏颜色较为暗沉、表面不粗糙、边缘呈锯齿状、肾脏呈大理石色，表面凹凸不平等；心肌细胞胞质疏松淡染肥大细胞浸润；肝索结构不清，肝细胞淀粉样变，呈嗜酸性均质状汇管区周围胆管增生，炎性细胞浸润；脾小结数量减少，红髓淋巴细胞减少，并可见大面积淀粉样变，呈嗜酸性均质状，髓窦可见淤血及出血。肺脏肺泡壁明显增厚，肺泡出血；肾脏肾小管上皮细胞空泡变性，胞质内可见微小空泡肾小管扩张，形状不规则，肾小球内可见炎性细胞浸润，少量肾小球萎缩，肾小囊内充满嗜酸性蛋白液等病理变化。本研究对混合感染致病性大肠杆菌、致病性棒状杆菌和致病性绿色气球菌的竹鼠病例组织进行了组织病理学观察和分析，以期为竹鼠细菌病的研究提供病理学参考资料

D-最优混料设计优化速冻专用油脂乳化剂配方Optimization of emulsifier formula of fast-frozen special fat by D-optimum mixture design

为解决速冻食品易开裂的问题，对速冻专用油脂乳化剂配方进行设计优化。首先以自制酯交换油脂为基料油，以吸水性和乳化稳定性为指标，对6种常用的亲油性乳化剂进行筛选，并采用D-最优混料设计确定最佳乳化剂配方，然后用该乳化剂配方制备速冻专用油脂，并将自制速冻专用油脂和两种市售速冻专用油脂制作速冻汤圆作应用对比试验。结果表明：以酯交换油脂为基料油的速冻专用油脂最佳乳化剂配方为硬脂酰乳酸钙添加量34.4%、单硬脂酸甘油酯添加量338%、大豆卵磷脂添加量31.8%，在此条件下复合乳化剂的吸水性为25.1 mL/10 g，乳化稳定性为933%；相比于市售速冻专用油脂，自制速冻专用油脂制作的速冻汤圆表面光滑、裂纹少，冻裂率和冷冻失水率低。因此，优化得到的速冻专用油脂复合乳化剂具备良好的乳化稳定性和持水能力，可降低速冻食品的冻裂率。In order to solve the cracking problem of fast-frozen food, the emulsifier formula of fast-frozen special fat was optimized. With water absorption and emulsifying stability as indexes, using self-made transesterification oil as base oil, six commonly used lipophilic emulsifiers were selected, and the best emulsifier formula was determined by D-optimum mixture design. In addition, the application of self-made fast-frozen special fat and two kinds of commercial fast-frozen special fat to produce fast-frozen dumpling was compared. The results showed that with self-made transesterification oil as base oil, the optimal emulsifier formula for fast-frozen special fat was obtained as follows: dosage of calcium stearoyl lactylate 34.4%, dosage of glycerol monostearate 33.8%, and dosage of soybean lecithin 318%. Under these conditions, the water absorption and emulsifying stability of compound emulsifier were 25.1 mL/10 g and 93.3%, respectively. Compared with the commercial fast-frozen special fat, the fast-frozen dumpling made by the self-made fast-frozen special fat had a smooth surface, fewer cracks, lower freeze-cracking rate and freezing water loss rate. The optimized compound emulsifier has good emulsifying stability and water-holding capacity, and can reduce the freeze-cracking rate of fast-frozen food