【作者】 王丽敏；

【导师】 胡小松；

【作者基本信息】 中国农业大学 ， 食品科学， 2004， 硕士

【摘要】 本文利用传统的分离方法和API菌种鉴定系统对苹果中的微生物类群进行分离鉴定，研究目的在于了解苹果中存在的主要微生物种类，为在苹果汁生产过程中有目的地控制微生物具有一定的帮助作用，利用自行研制的强磁脉冲杀菌设备研究高强度脉冲磁场对苹果汁中主要腐败菌酿酒酵母、大肠杆菌、金黄色葡萄球菌、沙门氏菌的致死机理 苹果中的菌落总数为10~5～10~7cfu／g之间，从苹果中分离得到25株酵母菌，API 20C AUX系统鉴定结果是：克柔／平常假丝酵母(Candida krusei)13株、酿酒酵母(Saccharomyces cerevisiae)5株、克勒克酵母属(Kloeckera spp．)2株、木蓝假丝酵母(Candida magnoliae)2株、热带假丝酵母(Candida tropicalis)1株和乳酒假丝酵母(Candida kefyr)1株，鉴定准确率＞95％；6株芽孢杆菌，API 50CHB鉴定结果是：枯草芽孢杆菌(Bacillus subtilis)4株、地衣芽孢杆菌(Bacillus licheniformis)2株，鉴定准确率＞90％；10株乳酸菌，API 50CHL鉴定结果是：植物乳杆菌(Lactobacillus plantarum)6株、嗜酸乳杆菌(Lactobacillus acidophilus)2株和短小乳杆菌(Lactobacillus brevis)1株，鉴定准确率＞85％。 大肠杆菌、酿酒酵母、沙门氏菌和金黄色葡萄球菌经脉冲强磁场处理(4.2T，30个脉冲数)后，扫描电镜(SEM)的结果表明四种菌的形态均发生明显的变化；流式细胞仪(FCM)的结果是：四种菌内部均产生物理损伤，荧光吸收量增加，增加的幅度为金黄色葡萄球菌＞沙门氏菌＞大肠杆菌＞酿酒酵母。通过SEM和FCM观察，支持了脉冲强磁场的作用位点为细胞膜的理论，通过破坏菌体的细胞膜导致微生物的死亡。更多还原

【Abstract】 The API identification system in combination with classical isolation methods was used as an original approach to determine the strains of microbes from apples. The main aim of this research paper was to learn about the microorganisms in apples and to help controlling the microbes during fruit juice processing. Furthermore the physiological states of damaged cells of Saccharomyces cerevisiae, Escherichiae coli, Salmonella sp. and Staphylococcus aureus after pulsed high magnetic field were investigated.The number of total clones in apples was found to range from 105 to 107 cfu/g. The identification of strains isolated by API system revealed 25 yeast species representing 6 genera: Candida krusei (13), Saccharomyces cerevisiae (5), Kloeckera spp. (2), Candida magnoliae (2), Candida tropicalis (1) ,Candida kefyr (1), the accuracy of identification was >95%. 6 bacillus strains: Bacillus subtilis (4), Bacillus licheniformis (2), the accuracy of identification was >90% and 10 lactobacillus strains: Lactobacillus plantanan (6), Lactobacillus acidophilus (2), Lactobacillus brevis (1), the accuracy of identification was >85%.Scanning electronmicroscopy (SEM) revealed that the E.coli, S.cerevisiae, Salmonella and S.aureus cells treated by pulsed high magnetic field for 4.2 T and 30 pulses some physical damages were inflicted and flow cytometry (FCM) revealed that the damage cells’ membrane integrity was damaged. The emission of treated cells was S.aureus>Salmonella>E.coli> S.cerevisiae. The SEM and FCM demostrated that the center point of treated cells by pulsed high magnetic field was membrane.更多还原