本文主要研究内容
作者汪浪红（2019）在《柚皮素协同脉冲电场杀灭大肠杆菌和金黄色葡萄球菌机制研究》一文中研究指出：食品的微生物污染不仅引起食品腐败变质和营养损失,甚至危害人类健康。人工合成防腐剂被广泛运用于食品当中抑制病原体的生长并延长其保质期。然而,人们对这些物质的安全隐患表示非常担忧。此外,越来越多的消费者更青睐于天然或“绿色”保鲜技术,既能做到防止食源性病原体的生长,又能最大程度保持营养品质。脉冲电场(Pulsed electric fields,PEF)作为一种近年来研究最为广泛的非热杀菌技术,以其良好的灭菌效果且能最大限度地保持食品营养成分等特点而备受瞩目。PEF主要通过破坏微生物细胞膜而将其灭活,然而具体作用机制不明确,尤其是关于细胞膜脂的变化与PEF灭菌之间的联系几乎处于空白。为了获得一个满意的灭菌效果,常需要增加场强和处理时间,但这会增加设备负荷以及造成能耗增加,甚至会导致处理样品的温度过高,引起热效应。因此各种PEF协同处理成为了研究的热点。柚皮素是一种在柑橘类植物中发现的生物活性黄酮类化合物,具有抑菌活性。但很少有研究报道评估柚皮素的抗菌机制,其作用方式仍未完全了解。基于此,本研究以大肠杆菌和金黄色葡萄球菌为对象,详细的研究柚皮素抗菌机制,并以其作为应激因子,探究大肠杆菌和金黄色葡萄球菌遭受膜理化性质包括流动性和脂质组成的变化与PEF耐受性之间的关系;同时利用柚皮素天然的抗菌特性,研究其与PEF协同灭菌作用,进一步探求两者协同的机制。本研究为寻求一种新的PEF协同灭菌技术和定向调控微生物细胞膜的方法提供理论基础,具有重要的理论意义和应用价值。具体的研究结果如下:柚皮素对大肠杆菌和金黄色葡萄球菌的生长存在一定的抑制作用,气质联用和荧光偏振分析表明大肠杆菌和金黄色葡萄球菌细胞在暴露于柚皮素后通过改变膜脂肪酸的组成来增加膜的流动性。其中,大肠杆菌细胞减少了细胞膜中环状和饱和脂肪酸的含量而产生更多的不饱和脂肪酸(18.5%增加至43.3%)。金黄色葡萄球菌则将反异构支链脂肪酸的比例从37.2%增加到54.4%,而异构支链和直链脂肪酸从30.0%和33.1%分别减少到21.6%和23.7%。实时q-PCR分析显示,fabA基因的表达除外,柚皮素诱导这两种菌的脂肪酸生物合成相关基因的表达下调;大肠杆菌应激sigma因子rpoS表达有轻微的降低,而金黄色葡萄球菌sigB基因表达明显下调,这种差异性可能与这两种菌对柚皮素的耐受性存在直接的联系。另外,研究发现,柚皮素可直接结合至大肠杆菌和金黄色葡萄球菌细胞膜蛋白质中,导致膜蛋白构象发生显著变化,改变了苯丙氨酸,酪氨酸和色氨酸残基的微环境。柚皮素能够导致这两种细菌膜电位去极化,引起细胞膜破裂,胞内物质泄漏,并且经历了形态学变化。使用紫外-可见光谱结合多变量曲线分辨率-交替最小值分析了柚皮素与细菌基因组DNA反应过程,解析出反应过程中两者的浓度变化和反应物光谱数据,证实柚皮素与DNA发生了相互作用。利用DNA的熔点和分子对接技术验证柚皮素与DNA的结合模式,揭示了柚皮素可以通过沟槽模式结合至基因组DNA的A-T碱基富集区,原子力显微镜表明柚皮素在这种相互作用可以扰动DNA的双螺旋结构,诱导这种生物大分子的形态发生变化。遭受柚皮素应激的大肠杆菌和金黄色葡萄球菌没有显著改变其对PEF处理的耐受性。然而,大肠杆菌和金黄色葡萄球菌对柚皮素适应后对PEF的耐受性逐步降低,导致细胞膜完整性破坏严重程度增加,因而产生更多的受损形态变化。大肠杆菌和金黄色葡萄球菌对PEF不同的耐受性可能与其暴露于柚皮素后细胞膜脂肪酸的改变有关。对柚皮素适应的金黄色葡萄球菌显著增加了反异构支链脂肪酸的含量,同时降低了直链和异构支链脂肪酸的水平,而大肠杆菌细胞则降低了细胞膜中饱和脂肪酸和环状脂肪酸的含量,合成了更多的不饱和脂肪酸和环状脂肪酸,这种膜脂的改变导致细胞膜的流动性增加。相比之下,经受柚皮素应激后,这两种细菌细胞膜脂肪酸组成没有观察到显著变化。以橙汁、葡萄汁和荔枝汁为研究体系,探究了较低浓度下(0~0.2 g/L)的柚皮素与PEF协同处理对这三种果汁中的灭菌效应。研究表明,柚皮素在此浓度下对果汁中的细菌有一定的抑制作用。PEF对这三种果汁中接种的大肠杆菌和金黄色葡萄球菌的灭活效应与其pH值存在一定的相关性(葡萄汁<荔枝汁<橙汁),其中葡萄汁中细菌的灭活度最大,荔枝汁次之,橙汁最差。柚皮素与PEF的协同作用对橙汁、葡萄汁和荔枝汁中的大肠杆菌和金黄色葡萄球菌产生了一定的灭菌增效作用,且随着柚皮素的浓度和电场强度增加,协同增效越明显。此外,在低温贮藏下,相比于对照组、柚皮素处理组和PEF处理组,柚皮素与PEF协同处理很好的抑制了细菌的生长。
Abstract
shi pin de wei sheng wu wu ran bu jin yin qi shi pin fu bai bian zhi he ying yang sun shi ,shen zhi wei hai ren lei jian kang 。ren gong ge cheng fang fu ji bei an fan yun yong yu shi pin dang zhong yi zhi bing yuan ti de sheng chang bing yan chang ji bao zhi ji 。ran er ,ren men dui zhe xie wu zhi de an quan yin huan biao shi fei chang dan you 。ci wai ,yue lai yue duo de xiao fei zhe geng qing lai yu tian ran huo “lu se ”bao xian ji shu ,ji neng zuo dao fang zhi shi yuan xing bing yuan ti de sheng chang ,you neng zui da cheng du bao chi ying yang pin zhi 。mai chong dian chang (Pulsed electric fields,PEF)zuo wei yi chong jin nian lai yan jiu zui wei an fan de fei re sha jun ji shu ,yi ji liang hao de mie jun xiao guo ju neng zui da xian du de bao chi shi pin ying yang cheng fen deng te dian er bei shou zhu mu 。PEFzhu yao tong guo po huai wei sheng wu xi bao mo er jiang ji mie huo ,ran er ju ti zuo yong ji zhi bu ming que ,you ji shi guan yu xi bao mo zhi de bian hua yu PEFmie jun zhi jian de lian ji ji hu chu yu kong bai 。wei le huo de yi ge man yi de mie jun xiao guo ,chang xu yao zeng jia chang jiang he chu li shi jian ,dan zhe hui zeng jia she bei fu he yi ji zao cheng neng hao zeng jia ,shen zhi hui dao zhi chu li yang pin de wen du guo gao ,yin qi re xiao ying 。yin ci ge chong PEFxie tong chu li cheng wei le yan jiu de re dian 。you pi su shi yi chong zai gan ju lei zhi wu zhong fa xian de sheng wu huo xing huang tong lei hua ge wu ,ju you yi jun huo xing 。dan hen shao you yan jiu bao dao ping gu you pi su de kang jun ji zhi ,ji zuo yong fang shi reng wei wan quan le jie 。ji yu ci ,ben yan jiu yi da chang gan jun he jin huang se pu tao qiu jun wei dui xiang ,xiang xi de yan jiu you pi su kang jun ji zhi ,bing yi ji zuo wei ying ji yin zi ,tan jiu da chang gan jun he jin huang se pu tao qiu jun zao shou mo li hua xing zhi bao gua liu dong xing he zhi zhi zu cheng de bian hua yu PEFnai shou xing zhi jian de guan ji ;tong shi li yong you pi su tian ran de kang jun te xing ,yan jiu ji yu PEFxie tong mie jun zuo yong ,jin yi bu tan qiu liang zhe xie tong de ji zhi 。ben yan jiu wei xun qiu yi chong xin de PEFxie tong mie jun ji shu he ding xiang diao kong wei sheng wu xi bao mo de fang fa di gong li lun ji chu ,ju you chong yao de li lun yi yi he ying yong jia zhi 。ju ti de yan jiu jie guo ru xia :you pi su dui da chang gan jun he jin huang se pu tao qiu jun de sheng chang cun zai yi ding de yi zhi zuo yong ,qi zhi lian yong he ying guang pian zhen fen xi biao ming da chang gan jun he jin huang se pu tao qiu jun xi bao zai bao lou yu you pi su hou tong guo gai bian mo zhi fang suan de zu cheng lai zeng jia mo de liu dong xing 。ji zhong ,da chang gan jun xi bao jian shao le xi bao mo zhong huan zhuang he bao he zhi fang suan de han liang er chan sheng geng duo de bu bao he zhi fang suan (18.5%zeng jia zhi 43.3%)。jin huang se pu tao qiu jun ze jiang fan yi gou zhi lian zhi fang suan de bi li cong 37.2%zeng jia dao 54.4%,er yi gou zhi lian he zhi lian zhi fang suan cong 30.0%he 33.1%fen bie jian shao dao 21.6%he 23.7%。shi shi q-PCRfen xi xian shi ,fabAji yin de biao da chu wai ,you pi su you dao zhe liang chong jun de zhi fang suan sheng wu ge cheng xiang guan ji yin de biao da xia diao ;da chang gan jun ying ji sigmayin zi rpoSbiao da you qing wei de jiang di ,er jin huang se pu tao qiu jun sigBji yin biao da ming xian xia diao ,zhe chong cha yi xing ke neng yu zhe liang chong jun dui you pi su de nai shou xing cun zai zhi jie de lian ji 。ling wai ,yan jiu fa xian ,you pi su ke zhi jie jie ge zhi da chang gan jun he jin huang se pu tao qiu jun xi bao mo dan bai zhi zhong ,dao zhi mo dan bai gou xiang fa sheng xian zhe bian hua ,gai bian le ben bing an suan ,lao an suan he se an suan can ji de wei huan jing 。you pi su neng gou dao zhi zhe liang chong xi jun mo dian wei qu ji hua ,yin qi xi bao mo po lie ,bao nei wu zhi xie lou ,bing ju jing li le xing tai xue bian hua 。shi yong zi wai -ke jian guang pu jie ge duo bian liang qu xian fen bian lv -jiao ti zui xiao zhi fen xi le you pi su yu xi jun ji yin zu DNAfan ying guo cheng ,jie xi chu fan ying guo cheng zhong liang zhe de nong du bian hua he fan ying wu guang pu shu ju ,zheng shi you pi su yu DNAfa sheng le xiang hu zuo yong 。li yong DNAde rong dian he fen zi dui jie ji shu yan zheng you pi su yu DNAde jie ge mo shi ,jie shi le you pi su ke yi tong guo gou cao mo shi jie ge zhi ji yin zu DNAde A-Tjian ji fu ji ou ,yuan zi li xian wei jing biao ming you pi su zai zhe chong xiang hu zuo yong ke yi rao dong DNAde shuang luo xuan jie gou ,you dao zhe chong sheng wu da fen zi de xing tai fa sheng bian hua 。zao shou you pi su ying ji de da chang gan jun he jin huang se pu tao qiu jun mei you xian zhe gai bian ji dui PEFchu li de nai shou xing 。ran er ,da chang gan jun he jin huang se pu tao qiu jun dui you pi su kuo ying hou dui PEFde nai shou xing zhu bu jiang di ,dao zhi xi bao mo wan zheng xing po huai yan chong cheng du zeng jia ,yin er chan sheng geng duo de shou sun xing tai bian hua 。da chang gan jun he jin huang se pu tao qiu jun dui PEFbu tong de nai shou xing ke neng yu ji bao lou yu you pi su hou xi bao mo zhi fang suan de gai bian you guan 。dui you pi su kuo ying de jin huang se pu tao qiu jun xian zhe zeng jia le fan yi gou zhi lian zhi fang suan de han liang ,tong shi jiang di le zhi lian he yi gou zhi lian zhi fang suan de shui ping ,er da chang gan jun xi bao ze jiang di le xi bao mo zhong bao he zhi fang suan he huan zhuang zhi fang suan de han liang ,ge cheng le geng duo de bu bao he zhi fang suan he huan zhuang zhi fang suan ,zhe chong mo zhi de gai bian dao zhi xi bao mo de liu dong xing zeng jia 。xiang bi zhi xia ,jing shou you pi su ying ji hou ,zhe liang chong xi jun xi bao mo zhi fang suan zu cheng mei you guan cha dao xian zhe bian hua 。yi cheng zhi 、pu tao zhi he li zhi zhi wei yan jiu ti ji ,tan jiu le jiao di nong du xia (0~0.2 g/L)de you pi su yu PEFxie tong chu li dui zhe san chong guo zhi zhong de mie jun xiao ying 。yan jiu biao ming ,you pi su zai ci nong du xia dui guo zhi zhong de xi jun you yi ding de yi zhi zuo yong 。PEFdui zhe san chong guo zhi zhong jie chong de da chang gan jun he jin huang se pu tao qiu jun de mie huo xiao ying yu ji pHzhi cun zai yi ding de xiang guan xing (pu tao zhi <li zhi zhi <cheng zhi ),ji zhong pu tao zhi zhong xi jun de mie huo du zui da ,li zhi zhi ci zhi ,cheng zhi zui cha 。you pi su yu PEFde xie tong zuo yong dui cheng zhi 、pu tao zhi he li zhi zhi zhong de da chang gan jun he jin huang se pu tao qiu jun chan sheng le yi ding de mie jun zeng xiao zuo yong ,ju sui zhao you pi su de nong du he dian chang jiang du zeng jia ,xie tong zeng xiao yue ming xian 。ci wai ,zai di wen zhu cang xia ,xiang bi yu dui zhao zu 、you pi su chu li zu he PEFchu li zu ,you pi su yu PEFxie tong chu li hen hao de yi zhi le xi jun de sheng chang 。
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论文作者分别是来自华南理工大学的汪浪红，发表于刊物华南理工大学2019-10-23论文，是一篇关于天然抗菌成分论文,脉冲电场论文,膜脂肪酸论文,流动性论文,协同灭菌论文,华南理工大学2019-10-23论文的文章。本文可供学术参考使用，各位学者可以免费参考阅读下载，文章观点不代表本站观点，资料来自华南理工大学2019-10-23论文网站，若本站收录的文献无意侵犯了您的著作版权，请联系我们删除。
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