单核细胞增生李斯特菌对食品加工中的胁迫响应及其机制研究进展

单核细胞增生李斯特菌（简称单增李斯特菌）在食品加工过程中经常会遇到环境胁迫,如酸胁迫、热胁迫、冷胁迫、干燥和高渗透压胁迫以及交叉胁迫等,并产生应激反应,而经过环境胁迫的单增李斯特菌可显著增强其抵抗致死性环境胁迫的能力,给食品安全带来极大危害。单增李斯特菌的酸胁迫响应机制主要包括F0F1-ATPase系统、谷氨酸脱羧酶系统以及精氨酸脱亚胺酶系统。热休克蛋白、冷休克蛋白、相容性溶质在单增李斯特菌的热胁迫、冷胁迫和干燥及高渗透压胁迫反应中起重要作用。本文从以上几方面就单增李斯特菌对环境胁迫响应及其机制的研究现状进行了综述,并提出了今后可能的研究方向,为单增李斯特菌在食品加工过程中的胁迫响应研究及防控提供指导。     

基于群体感应的单增李斯特菌生物膜形成与控制研究进展

单增李斯特菌的生物膜结构可以赋予细菌对消毒剂更强的耐受性,这使得如何有效清除其生物膜成为了食品加工业的难题。群体感应与细菌生物膜的形成、毒力侵袭特性和应激响应等生理特性密切相关。因此,本文概述了单增李斯特菌生物膜的特性,重点从群体感应（呋喃糖基硼酸二酯系统和寡肽自诱导因子系统）角度阐述了单增李斯特菌生物膜的形成机制,并综述了当前控制单增李斯特菌生物膜形成的可行方法及植物提取物作为群体感应抑制剂的研究现状。以期为预防和控制单增李斯特菌生物膜的形成提供新思路。     

单增李斯特菌生物膜形成及其调控机制研究进展

单增李斯特菌是一种重要的食源性致病菌,极易在食品接触表面形成难以清除的生物膜,导致食品持续性的污染。细菌生物膜在形成量、活细菌数量、微观结构等方面受到环境因素及菌株自身特性的影响。在单增李斯特菌的生物膜形成过程中,多种调控机制发挥着重要的作用。该文介绍了细菌生物膜的形成过程及影响单增李斯特菌生物膜形成的重要因素,简述了与单增李斯特菌生物膜相关的基因调控、胞外聚合物质分泌与群体感应系统调节的研究进展,有助于更好地理解其生物膜形成的复杂生理过程,为单增李斯特菌生物膜的污染及防控提供一定参考。     

二氧化氯对食品中食源性致病菌杀菌效果研究

试验用二氧化氯(ClO_2)溶液对已接种沙门氏菌和单增李斯特氏菌的黄瓜进行浸泡处理,研究Cl O_2溶液质量浓度、Cl O_2溶液温度和处理时间这3个因素对杀菌效果的影响,并利用中心组合试验设计(CCD)建立这3个因素与杀菌效果之间的数学模型。研究表明,随着Cl O_2溶液质量浓度和温度增大,杀菌效果提高,处理时间延长能提高杀菌效果,但上升趋势随时间延长变得平缓。ClO_2溶液质量浓度、ClO_2溶液温度和处理时间对沙门氏菌和单增李氏菌的杀菌效果均有极显著影响,且3个因素彼此之间交互作用显著。对沙门氏菌和单增李斯特菌杀菌效果的影响顺序分别为ClO_2溶液温度处理时间ClO_2溶液质量浓度、ClO_2溶液温度ClO_2溶液质量浓度处理时间。Cl O_2对沙门氏菌和单增李斯特菌杀菌效果的数学模型预报值与实测值基本一致,相对误差分别为1.20%和1.64%,建立的数学模型能描述ClO_2对黄瓜中沙门氏菌和单增李氏菌的杀菌规律,并能准确预测杀菌效果。     

食品加工环境胁迫因素对单核细胞增生李斯特菌生物膜形成的影响研究进展

单核细胞增生李斯特菌（以下简称单增李斯特菌）生物膜的生长可导致反复的食物污染。食品加工储藏常用的冷藏、干燥、酸处理以及消毒剂处理等使微生物长期处于胁迫环境下，对生物膜的形成产生影响。本文总结了常见的食品加工胁迫因素对单增李斯特菌生物膜形成的影响，其中重点介绍消毒剂处理对单增李斯特菌生物膜形成的影响，同时从膜流动性相关的适应策略、生物膜形成相关蛋白和基因调控表达的角度阐述胁迫条件下单增李斯特菌生物膜的形成机制。胁迫环境下单增李斯特菌生物膜形成的研究有助于揭示真实环境下其生物膜的形成及变化规律；充分考虑环境因素设定清洁、消毒标准有利于降低食源性致病菌传播的潜在风险。     

单增李斯特菌增殖的影响因素研究

本实验研究在冷却肉中单增李斯特菌的增殖以及产溶血素情况,考查与冷却肉相关的各种理化和生物因素对单增李斯特菌增殖的影响。研究表明,单增李斯特菌在所选择的温度范围内,温度越低,增殖受到的影响越大,同时低于0.93的水分活度下或pH低于5.0,单增李斯特菌失去增殖的能力。另外,初始菌数和气体环境也对单增李斯特菌产生了影响,冷却肉中存在的腐败菌和20%以上浓度的CO2都抑制了单增李斯特菌的增殖。     

多重PCR检测4种常见食源性致病菌

目的 建立一种多重聚合酶链式反应法(multiplex polymerase chain reaction, MPCR)快速检测肉制品中金黄色葡萄球菌、沙门氏菌、志贺氏菌和单增李斯特氏菌的分析方法。方法 选取金黄色葡萄球菌nuc基因、沙门氏菌SipB基因、志贺氏菌ipaH基因、单增李斯特菌inlA基因作为目标基因, 设计4对PCR引物, 建立并优化多重PCR反应体系, 评价该体系的特异性和灵敏度, 并对人工污染的熟肉样品进行检测。结果 构建的多重PCR方法特异性强、灵敏度高, 人工污染熟肉匀浆中4种致病菌的检出限为103 CFU/mL。结论 构建的多重PCR检测方法能够快速、准确、高效地检测肉制品中金黄色葡萄球菌、沙门氏菌、志贺氏菌和单增李斯特氏菌, 为食源性疾病菌的快速检测提供参考依据。     

惠阳区市售熟肉制品污染现状及膳食风险评估

目的：了解惠阳区市售熟肉制品污染现状,评估膳食风险,为辖区食品安全风险评估提供数据支撑。方法：随机采集惠阳区商超和农贸市场销售的熟肉制品54份,按照国家标准和地方标准对沙门氏菌、单增李斯特氏菌、金黄色葡萄球菌和亚硝酸盐进行检测与分析,根据危害系数和膳食风险评估概率对辖区熟肉制品进行风险评价。结果：市售熟肉制品中沙门氏菌、单增李斯特氏菌、金黄色葡萄球菌和亚硝酸盐合格率分别为96.3%、98.15%、100%和100%,沙门氏菌和单增李斯特氏菌污染水平无差异。农贸市场主要受沙门氏菌、单增李斯特氏菌和亚硝酸盐污染,商超主要受金黄色葡萄球菌和亚硝酸盐污染。农贸市场熟肉制品合格率为88.89%,商超熟肉制品合格率为100%,商超和农贸市场亚硝酸盐污染水平无差异。风险分析发现熟肉制品的危害系数最大值为0.46,膳食风险评估概率均<100%。结论：惠阳区市售熟肉制品不同程度检出了4种污染物,农贸市场食品安全风险大于商超,金黄色葡萄球菌和亚硝酸盐污染水平较低,暂不存在膳食摄入风险。     

多重荧光定量聚合酶链反应法检测肉制品中的3种食源性致病菌

摘要：目的 建立多重荧光定量聚合酶链反应法（quantitative polymerase chain reaction,qPCR）快速检测肉制品中沙门氏菌、单增李斯特菌、大肠杆菌O157:H7 3种食源性致病菌的方法。方法 根据沙门氏菌的invA基因、单增李斯特菌的hemolysin基因、大肠杆菌O157:H7的rfbE基因序列分别设计特异性引物及探针,通过优化反应体系,测定其灵敏度、特异性和重复性,建立了可同时检测上述3种食源性致病菌多重qPCR方法。结果 该方法只扩增3种靶细菌,对其他供试菌不扩增;沙门氏菌、单增李斯特菌、大肠杆菌O157:H7的检出限分别为101、102、102拷贝数/μL,并且拥有良好的重复性和特异性。人工污染的猪肉样品经SLE（Salmonella、Listeria monocytogenes and Escherichia coli 3种菌株的共增菌培养基）培养基富集8 h后,分别可以检测到初始菌液浓度为1.56×102 CFU/25 g的沙门氏菌,2.13×102 CFU/25 g的单增李斯特菌,2.32×102 CFU/25 g的大肠杆菌O157:H7。结论 所建立的多重qPCR灵敏度高、特异性强、重复性好,可同时检测肉制品中沙门氏菌、单增李斯特菌和大肠杆菌O157:H7 3种食源性致病菌,在提高食品安全和保护人类健康方面有重要意义。     

荧光假单胞菌、沙门氏菌和单增李斯特菌多重PCR检测方法的建立

针对肉制品中易污染的荧光假单胞菌、沙门氏菌和单增李斯特菌等有害微生物,通过3 种标准菌株及肉制品建立多重聚合酶链式反应方法,实现肉制品中这3 种菌的同时、快速检测。利用荧光假单胞菌的gyrB基因、沙门氏菌的invA基因和单增李斯特菌的hlyA基因设计3 对特异性引物,在确定引物特异性的基础上,对3 种标准菌株及在冷却肉上过夜富集后进行灵敏度检测。结果表明,该多重聚合酶链式反应方法对于同时检测这3 种有害微生物具有高度的特异性;同时检测这3 种菌时,纯菌DNA检测限可达1 pg/μL;将3 种菌一起接种到冷却肉中35 ℃过夜培养后,荧光假单胞菌、沙门氏菌和单增李斯特菌的检测限分别可达到9、5、70 CFU/mL。     

FATE OF LISTERIA MONOCYTOGENES AND SALMONELLA SPP. IN THERMALLY PROCESSED COLOR-MODIFIED TURKEY MEAT

The growth/survival of Listeria monocytogenes and Salmonella spp. was evaluated in two thermally-processed turkey raw materials. Flaked turkey (FT) was prepared from boneless, skinless thighs. Portions were washed with sodium phosphate buffers to lighten tissue color and produce color-modified turkey (CMT). Raw materials were cooked, inoculated with pathogens, and held at 4 and 20C. Salmonella numbers declined in cooked samples stored at 4C for 21 days, but increased by approximately 6 logs in 2 days for the FT and CMT held at 20C. L. monocytogenes increased by approximately 5 logs in samples held for 14 days at 4C. By 2 days at 20C, L. monocytogenes increased more than 5 logs in both materials. Growth/survival of these pathogens did not differ (p > 0.05) between FT and CMT. The data suggest that CMT does not present any more health hazards than conventional turkey raw materials.     

Survival of acid-adapted or non-adapted Salmonella Enteritidis, Listeria monocytogenes and Escherichia coli O157:H7, in traditional Greek salads

The fate of three pathogens Salmonella Enteritidis, Listeria monocytogenes and Escherichia coli O157:H7 that were inoculated in fish roe salad and aubergine salad with or without preservatives after being adapted in acid environment or not, was determined. The salads were stored at 10  ° C and the pathogens population was counted at regular intervals. Parameters (lag time, death rates calculated with Baranyi equation) were used to compare the behaviour of the pathogens. In the absence of preservatives the pathogens survived during the 15 days of storage. A 1 log reduction was observed for Listeria and 2 logs reduction for Salmonella and E. coli in both salads. In most cases, acid adaptation decreased the death rate even in the presence of preservatives. The addition of sorbic and benzoic acid in the salads increased the death rate of the pathogens during storage significantly and they were not detected at 7–10 days for Salmonella , 8–12 days for Listeria and 5 days for E. coli . It is concluded that a well-studied combination of hurdles is appropriate to ensure safety of home-made traditional salads free of preservatives.     

肉中4种致病菌的PCR快速检测方法的建立

目的:建立一种能同时检测肉中金黄色葡萄球菌、志贺氏菌、沙门氏菌和单核增生李斯特菌的多重PCR检测方法。方法:根据金黄色葡萄球菌的耐热核酸酶基因(nuc)、沙门氏菌的侵袭蛋白基因(invA)、志贺氏菌的侵袭性质粒抗原基因(ipaH)和单核细胞增生性李斯特菌的内化素基因(inlA)设计引物,通过优化好的反应体系进行多重聚合酶链反应(PCR)扩增目的基因。结果:特异性实验结果表明4种菌均能在相应位置扩增出特异性条带。对污染4种菌的猪肉进行检测,确定出金黄色葡萄球菌和沙门氏菌的检出限是102CFU/mL,志贺氏菌和单核增生李斯特菌的检出限是101CFU/mL。结论:本实验建立的多重PCR方法比传统细菌检测方法更特异、快速、灵敏,适用于肉中金黄色葡萄球菌、志贺氏菌、沙门菌和单核增生李斯特菌的快速检测。     

丹东口岸2003-2005年进口海产品中3种致病菌的检验

目的掌握丹东口岸进口海产品中单核细胞增生李斯特菌、沙门菌和副溶血性弧菌污染情况。方法对丹东口岸2003-2005年进口的海产品3种致病菌的检验结果进行了分析。结果1965批进口海产品中检出不合格产品44批(2.24%)。其中32批(1.63%)检出单核细胞增生李斯特菌、6批(0.31%)检出沙门菌和6批(0.31%)检出副溶血性弧菌。不合格产品主要为冻章鱼、冻海螺、冻紫石房蛤、活河螺、冻河螺肉等。结论从丹东口岸进口的海产品3种致病菌的污染比较严重,特别是被单核细胞增生李斯特菌的污染最严重,海产品中冻章鱼和冻海螺被这3种致病菌的污染比较普遍。     

Incidence of Salmonella, Campylobacter jejuni, Campylobacter coli, and Listeria monocytogenes in poultry carcasses and different types of poultry products for sale on the Belgian retail market.

From January 1997 to May 1998, 772 samples of poultry carcasses and poultry products for sale on the retail market in Belgium were analyzed for the presence of Salmonella spp., Salmonella Enteritidis, Campylobacter jejuni, C. coli, and Listeria monocytogenes per 100 cm2 or 25 g. Poultry samples were contaminated with Salmonella (36.5%), C. jejuni and C. coli (28.5%), and L. monocytogenes (38.2%). In about 12.3% of the poultry samples, the L. monocytogenes contamination level exceeded 1 CFU per g or cm2. Significant differences in pathogen contamination rates of poultry products were noticed between the poultry products originating from Belgian, French, and U.K. abattoirs. Poultry products derived from broiler chickens running free in pine woods until slaughtering age (12 to 13 weeks) had a significantly (P < 0.05) lower contamination rate of Salmonella than poultry products from enclosed broilers slaughtered at the age of 6 to 8 weeks. A significantly (P < 0.05) lower pathogen contamination rate was noted for Salmonella, C. jejuni, and C. coli for poultry cuts without skin compared to poultry cuts with skin on. An increase in pathogen contamination rate was noticed during cutting and further processing. To diminish C. jejuni, C. coli, Salmonella, and L. monocytogenes contamination rates, hygienic rules of slaughter and meat processing must be rigorously observed. At the moment, zero tolerance for these pathogens is not feasible, and there is a need to establish criteria allowing these pathogens to be present at reasonable levels in the examined poultry samples.     

Efficacy of washing meat surfaces with 2% levulinic, acetic, or lactic acid for pathogen decontamination and residual growth inhibition

We compared spray washing at 55.4 °C with 2% levulinic acid to that with lactic or acetic acid for decontamination of pathogenic bacteria inoculated onto meat surfaces, and their residual protection against later growth of pathogenic bacteria. The model systems included Escherichia coli O157:H7 on beef plate, Salmonella on chicken skin and pork belly, and Listeria monocytogenes on turkey roll. In the decontamination studies, acid washes lowered recoverable numbers of pathogens by 0.6 to 1 log/cm(2) as compared to no-wash controls, and only lactic acid lowered the number of pathogens recovered as compared to the water wash. Washing with levulinic acid at 68.3 or 76.7 °C did not result in additional decontamination of E. coli. Acetic acid prevented residual growth of E. coli and L. monocytogenes, and it reduced numbers of Salmonella on chicken skin to below recoverable levels. Overall, levulinic acid did not provide as effective decontamination as lactic acid nor residual protection as acetic acid.     

2007年温州地区食源性致病菌污染调查分析

目的了解2007年温州地区食品中沙门菌、单核细胞增生李斯特菌、大肠杆菌O157∶H7、空肠弯曲菌、金黄色葡萄球菌、副溶血性弧菌、香港海鸥菌的污染状况,提高温州地区食源性疾病检测、预警和控制能力,有效地预防、预测食源性疾病的暴发。方法依据国家食源性疾病监测网2007年度工作手册进行。结果检测生鸡肉、生猪肉、生牛肉、生羊肉、散装熟肉制品、海水鱼、淡水鱼、冷菜等八大类,共检出各类病原菌74株。其中以金黄色葡萄球菌的总检出率为最高,检出20株,检出率达15.04%;其次为副溶血性弧菌,检出39株,检出率为9.75%;单核细胞增生李斯特菌和沙门菌分别检出9株和6株,检出率分别为3.77%和2.51%,未检出大肠杆菌O157∶H7、空肠弯曲菌、香港海鸥菌。结论温州地区各类食品存在一定的食源性致病菌污染,其中冷菜、海水鱼、散装熟肉制品是主要污染品种。     

蓝莓叶多酚组成及其抗食源性致病菌活性分析

利用高效液相色谱-二级质谱对蓝莓叶多酚组成进行研究,发现蓝莓叶多酚含有槲皮素-3-O-戊糖苷、绿原酸、新绿原酸、隐绿原酸、槲皮素-3-O-葡萄糖醛酸、山奈酚-3-O-葡萄糖苷、对香豆酰奎尼酸及B型原花青素二聚体等多种酚类物质;通过对6 种常见食源性致病菌的抗菌效果研究,发现蓝莓叶多酚具有广谱抗菌性,对鲍氏志贺氏菌、金黄色葡萄球菌、单增李斯特菌、大肠杆菌、肠炎沙门氏菌和枯草芽孢杆菌具有较好的抑制效果,对枯草芽孢杆菌（Bacillus subtilis,革兰氏阳性（G＋））和肠炎沙门氏菌（Salmonella enteritidis,革兰氏阴性（G－））最小抑菌浓度（minimal inhibitory concentration,MIC）＜9.30 mg/mL,对其他菌株的MIC＜4.65 mg/mL,抑菌活性由强到弱为：金黄色葡萄球菌＞大肠杆菌＞单增李斯特菌＞鲍氏志贺氏菌＞肠炎沙门氏菌＞枯草芽孢杆菌。结果表明：蓝莓叶多酚含有较多生物活性组分,抑菌性强且抑菌谱广泛,可以开发为新型天然防腐剂。     

Thermal inactivation of stationary-phase and acid-adapted Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes in fruit juices

The heat resistance of stationary-phase and acid-adapted Escherichia coli O157:H7, Salmonella enterica (serotypes Typhimurium, Enteritidis, Gaminara, Rubislaw, and Hartford), and Listeria monocytogenes was evaluated in single-strength apple. orange, and white grape juices adjusted to pH 3.9. The heat resistance increased significantly (P < 0.05) after acid adaptation. Salmonella had an overall lower heat resistance than the other pathogens. Acid-adapted E. coli O157:H7 presented the highest heat resistance in all juices at the temperatures tested, with lower z-values than Salmonella and L. monocytogenes. The heat resistance (D(60 degrees C)-values) of all three pathogens, assessed in tryptic soy broth adjusted to different pH values, increased above pH 4.0. From the results obtained in this study, one example of a treatment that will inactivate 5 logs of vegetative pathogens was calculated as 3 s at 71.1 degrees C (z-value of 5.3 degrees C). Normal processing conditions calculated for hot-filled, shelf-stable juices achieve a lethality in excess of 50,000 D for all three pathogens.