可生食蔬菜中单核细胞增生李斯特菌生存特征研究

目的 探究可生食蔬菜品种、温度、接种部位对单核细胞增生李斯特菌（以下简称单增李斯特菌）存活的影响,为可生食蔬菜中单增李斯特菌的风险评估和关键控制措施提供理论依据。方法 以冻干定量单增李斯特菌为菌株来源,以彩椒、洋葱、黄瓜、圣女果和生菜5种可生食蔬菜的表面和切面为单增李斯特菌的接种点,在4 ℃、25 °C条件下培养7 d,定期监测每份样本中的单增李斯特菌的菌量,对其生长情况进行分析。结果 单增李斯特菌冻干菌种不同瓶间菌量均匀（F=1.923,P<0.05）,-20 ℃储存28 d后的复苏率为93.3%±4.2%。在4 ℃条件下,除了彩椒表面、黄瓜切面、生菜表面和生菜切面外,单增李斯特菌在其他蔬菜上放置7 d后均未见显著生长（δ<0.5 log₁₀ CFU/mL）。在25 ℃条件下,单增李斯特菌在彩椒、洋葱、圣女果、生菜以及黄瓜切面上均呈现为支持生长［δ为（1.16±0.35）~（2.68±0.18）log₁₀ CFU/mL］。单增李斯特菌在黄瓜切面、生菜表面和切面放置7 d后,菌量仍持续增长,在生菜的表面和切面生长趋势和浓度基本一致。结论 单增李斯特菌在可生食蔬菜上的存活能力与蔬菜种类、表面与切面、储存温度等条件密切相关,温度的控制对降低其在可生食蔬菜中的风险至关重要。生菜和切后的黄瓜作为单增李斯特菌高风险食品,应引起风险评估的重视。     

Combined effect of packaging atmosphere and storage temperature on growth of Listeria monocytogenes on ready-to-eat shrimp

Cooked, peeled, and deveined shrimp were inoculated with a 5 strain mixture of Listeria monocytogenes and packaged in air, vacuum, and a 100% carbon dioxide modified atmosphere. The packaged shrimp were then stored at 3, 7, and 12 degrees C for 15 days to monitor the growth of L. monocytogenes and psychrotrophic bacteria. Uninoculated shrimp were also subjected to sensory evaluation by a trained panel to measure odor and appearance over the storage period. Results demonstrated that shrimp packaged in CO(2) and stored at 3 degrees C did not permit growth of L. monocytogenes during the 15-day storage period, while all other packaging/temperature combinations allowed for multiplication of the bacterium. Carbon dioxide packaging also resulted in the slowest growth of psychrotrophic bacteria and resulted in shrimp having acceptable sensory odor and appearance scores at the end of storage. When strict temperature control is difficult, such as during processing, transportation, retail display, or home use, additional antimicrobial hurdles may be necessary to ensure safety.     

单增李斯特菌生态行为模型构建及机制研究进展

目的 探究食品中的单增李斯特菌随食品链相关条件的变化而发生的"生长-失活-再生长"生态行为规律.方法 以热加工为失活条件,综述单增李斯特菌生态行为的影响因素、模型构建和相关机制.结果 单增李斯特菌在"生长-失活"过程中,细胞的历史生长条件会对其失活特性产生影响,在"失活-再生长"过程中,细胞的历史生理状态会影响其修复再生长的延滞期.结论 食品链中细菌的生长和失活是连续的过程,有必要研究在连续的环境条件变化过程中细胞的生态行为,以期为食品风险评估和食品安全防控提供支持.     

二烯丙基二硫醚对单增李斯特菌毒力基因表达的影响

二烯丙基二硫醚(DADS)是一种典型的硫醚类香料。该类香料在抗菌消炎,提高机体免疫力,预防和治疗心血管疾病等保健及药理作用方面具有显著效果。而对其在食源性致病菌中的抑制作用及相关机理研究较少。四大食源性致病菌之一单增李斯特菌(Listeria monocytogenes,LM)容易感染食物而引发脑膜炎、败血症及孕妇流产等一系列恶性疾病。本研究以如何高效抑制单增李斯特的生长为出发点,以DADS为研究对象,采用微量肉汤稀释法初步筛选出其对单增能李斯特菌的最小抑菌浓度(MIC),利用RT-qPCR技术考察其对单增李斯特菌毒力基因inlA、hlyA、prfA表达的影响。结果表明:亚抑菌浓度下DADS均可显著抑制毒力基因inlA、hlyA、prfA的表达,且抑制作用呈现一定的浓度依赖性,hlyA及prfA对其作用更敏感。     

Swabbing the surface: critical factors in environmental monitoring and a path towards standardization and improvement

Abstract

Cross-contamination can be broadly defined as the transfer, direct or indirect, of microorganisms from a contaminated product to a non-contaminated product. Events that may result in cross-contamination include inadequate hygiene practices, contaminated equipment surfaces, contamination via food handling personnel, further product processing, or storage abuse All of these niches require consistent environmental surveillance systems to monitor microbial harborage sites to prevent foodborne illnesses via cross-contamination. Environmental surveillance is achieved through routine surface sampling of the food contact surfaces and surrounding areas. To better understand cross-contamination, the role of environmental surface transmission during outbreaks due to the presence and persistence of pathogenic microorganisms on various food contact surfaces must be investigated. However, studies on environmental sampling techniques are rarely performed in an actual food processing environment but rather under controlled variables within a laboratory-setting. Moreover, results and conclusions of studies differ because of the considerable variability across surface sampling tools due to individual operator dependency, low recovery rates, and low reproducibility. Information is also often lacking on environmental sampling tools used within a processing facility, the characterization of these tools, and the optimization of recovery of microorganisms for surface sampling. Thus, this review aims to: (1) discuss and compare factors impacting the recovery of microorganisms and the standardization of surface sampling methods for optimal recovery of microorganisms and (2) examine how research strategies could focus more towards the development of standard methodologies for surface sampling.     

酵母菌促进单核细胞增生李斯特氏菌的生长

为了缩短单核细胞增生李斯特氏菌(单增李斯特氏菌)的前增菌时间,提升检测效率,本研究将酵母菌(ATCC9763)作为一种生长促进剂加入到单核细胞增生李斯特氏菌的前增菌培养基(LB1)中,结果表明添加适量的酵母菌可以使单增生李斯特氏菌的生长速度提升近100%,并且这种促进作用与培养过程中酵母菌的接种量、培养基的溶氧量以及培养方式密切相关。根据酵母菌的生长特性分析,这种促进作用产生的原因很有可能是由于酵母菌在生长过程中发酵分解了培养基中的糖类等营养物质,改善了单增李斯特氏菌的营养条件,从而提高了单增李斯特氏菌的繁殖速度。本研究为缩短单增李斯特氏菌检测的富集培养时间,提高检测效率奠定了很好的基础,同时也侧面提示我们要关注发酵类食品遭受单增李斯特氏菌污染的食品安全风险。     

食源性致病菌单增李斯特菌检测技术的研究进展

单增李斯特菌是一种兼性厌氧性食源性致病菌,对低温、高盐及消毒剂的抵抗力很强,感染后可能产生低热、高热或其他全身性疾病,免疫力低下的人可能会引起肠胃炎、孕妇流产、早产或死产,甚至会产生脑膜炎。LM的传统检测方法是先进行增菌,再经过氧化氢酶试验、溶血试验、血清学试验等进行鉴定,操作性强、灵敏度高、成本低,但是检测周期长达7 d,无法对目标食物进行快速检测。本文综述了振动光谱学检测方法、免疫学检测方法、分子生物学检测方法、代谢组学检测法、生物传感器等食源性单增李斯特菌的检测方法,并比较其优缺点,以期为食品中LM的快速检测方法的研究提供参考。     

9274份肉及肉制品食源性致病菌监测结果分析

目的 了解吉林省9274份肉及肉制品食源性致病菌污染情况,为防控食源性疾病提供科学依据。方法从吉林省9个地市级行政区采集市售6类肉及肉制品样品共9274份,包括生畜肉、生禽肉、熟肉制品、调理肉制品、冷冻肉糜制品和动物血液及制品。按照国家标准方法检测10种食源性致病菌。结果 全部9274份样本食源性致病菌总阳性检出率为3.9%(366/9274)。检出率最高为调理肉制品 (13.0%,63/483),其次是生禽肉(5.6%,107/1900)和生畜肉(5.0%,71/1428)。检出的主要致病菌为单核细胞增生李斯特菌、金黄色葡萄球菌和沙门菌。生禽肉中弯曲菌检出率(7.5%,31/411)和产气荚膜梭菌检出率(3.9%,7/180)均高于沙门菌检出率(3.5%,8/231)。生禽肉、生畜肉中未检出小肠结肠炎耶尔森菌。动物血液及制品未检出单细胞增生李斯特菌、弯曲菌和小肠结肠炎耶尔森菌。冷冻肉糜制品未检出沙门菌。熟肉制品未检出大肠埃希氏菌O157、志贺菌和蜡样芽胞杆菌。熟肉制品各年度检出率范围为1.3%-4.4%。结论 吉林省市售的肉及肉制品较长时间受到不同程度的食源性致病菌污染,存在食源性疾病发生的风险。     

苏州市食品中单增李斯特菌污染状况及分子特征分析

目的 研究2016-2020年苏州市各类食品中单增李斯特菌的污染状况及分子特征.方法 将采样食品按WS/T 464-2015《食物成分数据表达规范》进行分类,计算各类食品污染率,通过聚合酶链式反应(polymerase chain reaction,PCR)和凝胶电泳对毒力基因(inlA、inlB)和耐药相关基因(vi...