高渗适应德尔卑沙门氏菌对交叉环境胁迫抗性分析

为研究高渗适应性德尔卑沙门氏菌(Salmonella enterica subsp.enterica Derby)在高浓度NaCl交叉及其他胁迫环境耐受性的影响,将德尔卑沙门氏菌在含有质量分数4%NaCl的培养基中进行驯化,诱导高渗适应性。以具有高渗适应的德尔卑沙门氏菌为耐渗菌株,未适应的德尔卑沙门氏菌为对照菌株,经饱和NaCl处理4 h后,交叉不同温度、pH、胆盐、紫外线照射、消毒剂等胁迫环境的存活率来评价其耐受性。高渗适应德尔卑沙门氏菌在饱和NaCl胁迫环境的存活率提升1.46倍;在低温、NaOH、乙醇、双氧水、NaClO、紫外线照射胁迫时存活率高于对照菌株1～3倍;在65℃高温、胆盐和极酸环境条件下的存活率低于20%,生存受到抑制。德尔卑沙门氏菌经过质量分数4%NaCl驯化会诱导产生高渗适应性,还会协同提高对4℃低温、H₂O₂等胁迫环境的交叉抗性,但对高温、H₂O₂等杀菌措施敏感性提高。研究结果为腌制食品中沙门氏菌的防控提供一定的理论依据。     

非编码小RNA对食源性致病菌的调控机制

细菌性食物中毒属食品安全问题，其主要由食源性致病菌所致。在食品加工及贮藏阶段，细菌为了适应残酷的生存环境，进化出复杂的调控机制。如:通过改变自身基因的表达水平而提高存活率。细菌体内大量存在的非编码小分子RNA(sRNA)，在调控中起重要作用。sRNA能够通过多种方式促进或抑制蛋白的合成，这与细菌的生理机制表达、环境胁迫的耐受性等密切相关。因环境改变而诱导sRNA转录，进行调节的细菌，在生理与抗性上会产生显著性改变。可能导致细菌的抗性增强，难以被消灭，同时还会提高自身毒性而威胁人体的生命健康。本文主要综述sRNA对食源性致病菌致病性的影响，以及环境改变而受到胁迫时的调控方式，揭示细菌sRNA在生物适应性进化及生命活动中的作用。     

环境胁迫调控植物乳杆菌细菌素合成的研究进展

植物乳杆菌作为具有重要经济价值的乳酸菌被广泛应用于食品发酵与保鲜领域,由于其代谢过程中会产生具有广谱抑菌特性、对热稳定且易被蛋白酶水解的细菌素,因此有作为天然食品生物防腐剂的较大应用潜力。研究表明,在发酵过程中菌体的生长和细菌素的合成受多种环境因素如盐胁迫、酸胁迫、氧胁迫及低高温胁迫的影响,但目前环境因素调节信号分子产生以及调控相关基因合成细菌素的具体机制仍然有待研究,另一方面,通用的调控通路还未被发现。因此,本文介绍了植物乳杆菌抵御胁迫的反应机制并详细阐述了环境胁迫下与细菌素合成密切相关的调控基因和重要调控蛋白,为食品发酵加工过程中合理控制发酵条件,促进细菌素合成从而延长食品货架期提供理论依据。     

关于生鸡肉交叉污染的沙门氏菌

正据报道,有专家指出,按照测算结果,我国每年沙门氏菌食物中毒的发病人数达300万人次,其中近半数与生鸡肉交叉污染有关。专家解读一、沙门氏菌是主要食源性致病菌之一沙门氏菌(Salmonella)是经食物传播引起人类肠道疾病的主要食源性致病菌之一,在世界范围内几乎所有即食食品和大部分过程标准中均将沙门氏菌列为限量指标。沙门氏菌广泛分布于自然界,通常寄居在人或动物肠道内,可通过粪便污染环境和动物制品,动物和动物性食品是人感染沙门氏菌的重要来     

食品沙门氏菌免疫染色快速检验技术

沙门氏菌病是常见的食品传播性疾病。它的病原体便是沙门氏菌属细菌。由于沙门氏菌是食品传播性疾病的致病因子,故已引起世界各国越来越多的注意和重视。在荷兰首先发现并证明沙门氏菌主要寄生场所是人和动物的肠道,并在动物、人和环境之间存在传染循环。特别是生熟食品,从原料、生产工具、人等形成交叉污染,而经常引起沙门氏菌病的发生原因。1971年北美洲生产的巧克力糖,每克中虽只含有1个伊斯特本沙门氏菌,却引起了一次国际间爆发性食品中     

噬菌体防控沙门氏菌生物被膜的研究进展

沙门氏菌是重要的食源性致病菌，控制食品中沙门氏菌的污染，特别是防止其形成生物被膜交叉污染食品，对保障食品安全具有重要意义。现阶段传统的物理性、化学性控制措施都存在一定的局限性，难以有效将沙门氏菌生物被膜完全去除，因此，亟待开发针对沙门氏菌生物被膜的新型控制和清除策略。近年来噬菌体作为一种安全、有效、无残留的天然抑菌剂受到了普遍关注，与化学消毒剂相比，其具有特异性强、自我增殖快、安全性高、研发时间短等突出优势，在食源性致病菌生物被膜的控制和清除领域已表现出巨大潜力。该文综述了沙门氏菌生物被膜的结构成分与形成过程，并重点介绍了国内外用噬菌体破解沙门氏菌生物被膜的作用机制与应用现状。针对噬菌体的未来研究方向进行了展望，以期为食品加工过程中沙门氏菌生物被膜的有效控制提供新的技术与策略。     

食源性细菌低温适应的分子机制研究进展

冷藏可抑制食源性细菌的生长,延长食品的货架期,是最为常用的食品保藏策略。然而,许多食源性致病菌和腐败菌具有较强的低温适应能力,这严重威胁到食品的质量与安全。阐明食源性细菌低温适应的分子机制,对制定和实施更有效的控制措施是至关重要的。主要从食源性细菌低温应激响应关键基因的发掘,转录组学和蛋白组学在食源性细菌低温适应机制研究中的应用两个方面展开综述,以期为食源性细菌的研究和控制提供理论参考。     

基于转录组学分析酸胁迫影响鼠伤寒沙门氏菌耐酸能力的机理

目的：探究酸胁迫和非酸胁迫条件下鼠伤寒沙门氏菌（Salmonella typhimurium）的转录组反应,分析差异基因（differentially expressed genes,DEGs）表达水平,阐明酸胁迫影响鼠伤寒沙门氏菌耐酸反应（acid tolerance response,ATR）的相关代谢通路。方法：对鼠伤寒沙门氏菌进行酸胁迫处理,利用转录组测序技术和生物信息学分析相关DEGs,并通过实时聚合酶链式反应（real-time polymerase chain reaction,real-time PCR）进行验证。结果：经酸胁迫后,共筛选到683 个DEGs,其中上调343 个,下调340 个。其中涉及细胞运动、氨基酸代谢、细胞膜组成等通路上调能够使鼠伤寒沙门氏菌快速适应酸环境;碳水化合物代谢相关通路上调能够为鼠伤寒沙门氏菌快速适应酸环境提供更多的能量,与此同时,嘧啶代谢等能量代谢通路下调能够使鼠伤寒沙门氏菌降低能量消耗以维持上述的必需代谢过程;细菌应激调控相关通路上调赋予鼠伤寒沙门氏菌交叉保护抗性;鞭毛、外膜蛋白、脂多糖等毒力相关基因表达上调增强了鼠伤寒沙门氏菌的毒力。real-time PCR验证结果与转录组测序分析表达趋势一致。结论：酸胁迫显著提高了鼠伤寒沙门氏菌的耐酸能力,其中与代谢和细胞过程相关的通路发挥主要作用,本研究结果为进一步了解该菌的酸胁迫反应及更好地控制其在食品中的污染提供了理论依据。     

细菌生物被膜检测与清除方法研究进展

开展食源性致病菌的防控研究以保障食品安全,具有显著的实践意义。作为细菌为适应不良环境所表现出的一种自我保护机制,食源性致病菌在食品生产加工过程中,可以黏附在食品原材料表面以及各种食品加工器械表面形成生物被膜,增大了消毒清洗的难度,给食品安全带来了严重的隐患和危害。因此,如何有效地清除细菌生物被膜成为食品安全领域的研究热点。结合细菌生物被膜形成过程和调控机制,本研究系统分析总结了细菌生物被膜的检测与清除方法的现状,为实现细菌生物被膜的有效控制,消除由生物被膜造成的食品安全隐患提供了综合性的认识,可为研究人员解决细菌生物被膜带来的食源性微生物污染提供参考,对保障食品安全有重要意义。     

吉林地区食源性沙门氏菌状况研究及快速检测

目的 分析吉林市哨点医院食源性沙门氏菌监测病例,为防控食源性疾病爆发提供参考依据;为缩短检出时间,利用上转发光免疫层析技术对食源性沙门氏菌进行检测,并对其检测性能进行评价;方法 收集吉林地区哨点医院食源性沙门氏菌病例的监测信息进行研究分析;针对哨点医院细菌分离培养检出的食源性沙门氏菌,采用上转发光免疫层析方法进行检测; 结果 吉林地区食源性沙门氏菌在幼儿人群组检出率最高,疑似暴露食物主要是水果类及其制品、肉与肉制品和混合食品等三类食品,疑似暴露食物以散装最多,疑似暴露食物购买地点主要是市场,检出的食源性沙门氏菌主要是肠炎沙门氏菌和鼠伤寒沙门氏菌;对照细菌分离培养,上转发光免疫层析检测结果与其高度一致（符合率达100%）。结论 加强吉林市食品安全卫生监督,降低食源性疾病发生;上转发光免疫层析可满足食源性沙门氏菌菌株的快速检测。     

食品加工过程中致病菌控制的关键科学问题

致病性细菌是导致食源性疾病暴发的罪魁祸首,也是我国建立食品质量安全控制体系必须面对的重要危害.在食品加工过程中,食源性致病菌由于能够形成菌膜,进行亚致死损伤修复,调节抗性基因的表达等,从而对加工过程中的高温、高压、冷冻、脱水、光照、真空以及氧化等环境胁迫产生耐受性.此外,致病菌也能够分泌各种胞外毒力因子等,给食品安全带来极大的威胁.本文针对近年来食品加工过程中致病菌安全控制关键科学问题的研究进展进行阐述,并对未来的发展方向作展望.     

Membrane fluidity-related adaptive response mechanisms of foodborne bacterial pathogens under environmental stresses

The maintenance of bacterial membrane fluidity plays an important role in a variety of cell physiological functions such as nutrient transport, protection from external adverse environments, and cell morphology. The fluidity of membranes is modified in response to several environmental cues, enabling bacterial survival in otherwise unfavorable conditions. Many foodborne bacterial pathogens are able to survive a variety of food preservation treatments used to prevent microbial contamination. These pathogens are able to successfully exploit membrane fluidity-related adaptation strategies under unfavorable conditions, resulting in food hygiene failures. Factors involved in food preservation include pH, temperature, osmotic stress, antimicrobial agents, and high pressure. The fluidity of bacterial membrane lipid bilayer is altered mainly via the adjustment of membrane fatty acid composition. Under undesirable conditions, Gram-negative bacteria alter their membrane fluidity primarily by regulating the ratio of unsaturated fatty acids (UFAs) to saturated fatty acids (SFAs) and, to a lesser extent, the levels of cyclopropane fatty acids (CFAs), or by cis/trans isomerization. Gram-positive bacteria typically alter their membrane fluidity with changes in fatty acyl chain length or by forming branched-chain fatty acids (BCFAs), besides changes to the ratio of UFA to SFA. This review encompasses various modulators of membrane fluidity, particularly with respect to foodborne pathogens, which often survive even the hostile environments associated with food processing.     

Effect of high hydrostatic pressure and pressure cycling on a pathogenic Salmonella enterica serovar cocktail inoculated into creamy peanut butter

The ability of Salmonella enterica serovars to survive in high fat content, low water activity foods like peanut butter has been demonstrated by large foodborne illness outbreaks in recent years. This study investigates the potential of high hydrostatic pressure processing, including pressure cycling, to inactivate Salmonella inoculated into creamy peanut butter. A cocktail of pathogenic strains of Salmonella Enteritidis PT30, Salmonella Tennessee, Salmonella Oranienburg, Salmonella Anatum, Salmonella Enteritidis PT 9c, and Salmonella Montevideo obtained from peanut butter- and nut-related outbreaks was inoculated (10(6) to 10(7) CFU/g) into creamy peanut butter and high pressure processed under five different sets of conditions, which varied from 400 to 600 MPa and from 4 to 18 min. The log CFU reductions achieved varied from 1.6 to 1.9. Control experiments in which Salmonella was inoculated (10(9) CFU/g) into 0.1% peptone buffer and high pressure processed at 600 MPa for 18 min showed inactivation to below the detection limit of 100 CFU/g, confirming that high pressure processing is effective at destroying Salmonella in high-moisture environments. Pressure cycling under three sets of conditions consisting of pressures from 400 to 600 MPa, 3 to 10 pressure cycles, and hold times of 6 min for each cycle showed reductions similar to those seen in noncycling experiments. The results of our experiments suggest that the peanut butter food matrix facilitates the survival of Salmonella when exposed to high hydrostatic pressure processing.     

食源性沙门菌毒力岛基因分布及特征研究

目的研究食源性沙门菌毒力岛的分布特征及其与食物中毒的关系。方法收集市售食品、市售生鸡肉、食物中毒标本沙门菌分离株,进行血清学分型,并应用聚合酶链式反应方法检测沙门菌毒力岛(Salmonella pathogenicity island,SPI)基因SPI1~SPI5,进行统计学分析。结果 152株沙门菌菌株中,检出16种血清型,以肠炎沙门菌为优势血清型,不同来源的该血清型菌株的毒力岛谱型有差异。SPI1在食物中毒菌株中检出率最高,市售生鸡肉SPI1的携带率高于市售食品。结论沙门菌的毒力岛谱型分布与菌株的不同来源相关,其中SPI1与沙门菌食物中毒呈正相关,市售生鸡肉有引起沙门菌食物中毒的潜在风险。     

The physiology of Campylobacter species and its relevance to their role as foodborne pathogens

Campylobacter jejuni and C. coli are recognised as the leading causes of bacterial foodborne diarrhoeal disease throughout the development world. While most foodborne bacterial pathogens are considered to be relatively robust organisms, as a consequence of the necessity to survive the inimical conditions imposed by food processing and preservation, Campylobacter species have uniquely fastidious growth requirements and an unusual sensitivity to environmental stress. Campylobacters also lack many of the well characterised adaptive responses that can be collated with resistance to stress in other bacteria. The aim of this review is to outline the unusual physiology of campylobacters (C. jejuni and C. coli) and to describe how this influences their role as foodborne pathogens.     

2013—2020年广州市市售生食动物性水产品食源性致病菌监测结果分析

目的 了解2013—2020年广州市市售生食动物性水产品中食源性致病菌污染状况及分布特点。 方法 2013—2020年共采集631份生食动物性水产样品, 进行沙门氏菌、单核细胞增生李斯特氏菌、副溶血性弧菌、创伤弧菌、霍乱弧菌和致泻性大肠埃希氏菌等食源性致病菌检测。结果 检出食源性致病菌阳性样品90份, 总检出率为14.26%。生食动物性淡水产品和生食动物性海产品食源性致病菌检出率差异有统计学意义, ?2=160.375, P<0.001。生食动物性淡水产品检出率较高, 达到了45.70%。6种食源性致病菌检测结果显示, 创伤弧菌检出率最高, 达到9.51%, 其次是副溶血性弧菌5.86%, 沙门氏菌1.90%。第3季度检出率最高, 为16.15%, 最低的是第1季度(11.36%)。餐饮单位所售生食动物性水产品食源性致病菌检出率最高(21.90%), 其次为超市(7.69%), 网店和农贸肉菜市场所售商品无检出。结论 广州市市售生食动物性水产品存在不同程度的食源性致病菌污染, 致病菌污染主要以创伤弧菌、副溶血性弧菌为主, 生食动物性淡水产品污染情况更严重, 相关政府部门应加强监管, 开展健康宣传教育, 预防食源性疾病的发生。     

Microbial stress response in minimal processing.

"Bacteria have evolved adaptive networks to face the challenges of changing environments and to survive under conditions of stress. Therefore, the efficiencies of inactivation and preservation methods need to be assessed, especially with regard to the enormous potential of food pathogens to adapt to a wide variety of stress conditions. All adaptive responses, whether to changing nutrients or to various stresses encountered in minimal processing, involve a series of genetic switches that control the metabolic changes taking place. A common regulatory mechanism involves the modification of sigma (sigma) factors whose primary role is to bind to core RNA polymerase conferring promoter specificity directing expression of specialty regulons involved in heat-shock response, the chemotactic response, sporulation, and general stress response. Examples of the latter regulon in Gram-positive bacteria (the sigmaB regulon) and in Gram-negative bacteria (the RpoS regulon) will be discussed in more detail. Cellular adaptive mechanisms to starvation, cold shock, heat shock, (weak) acids, high osmolarity and high hydrostatic pressure will be described and their significance in food preservation and safety will be discussed."     

2015年吉林市食品安全风险监测结果分析

摘 要：目的 分析吉林市食源性致病菌污染情况,为预防和控制食源性疾病提供依据。方法 按照《2014年国家食品污染和有害因素风险监测工作手册方法》对食源性致病菌进行监测。结果 2015年吉林市共监测10类240份食品样本,检出19株致病菌,总检出率7.92%,其中检出7株蜡样芽孢杆菌,8株单核细胞增生李斯特氏菌,3株金黄色葡萄球菌,1株沙门氏菌;3类食品样本监测到食源性致病菌：流动早餐检出率57.14%,肉与肉制品检出率50%,调味品检出率2%;依据散装和预包装不同包装类型的食品样本中食源性致病菌的检出率差异有统计学意义。结论 吉林市流动早餐和肉与肉制品两类食品样本中检出食源性致病菌为金黄色葡萄球菌、蜡样芽胞杆菌、单核细胞增生李斯特菌,检出率均较高,相关部门需要加强对此类食品的监管。     

Germination and outgrowth of spores of Bacillus cereus group members: diversity and role of germinant receptors

Bacillus cereus is a Gram-positive, facultative anaerobic, endospore-forming toxicogenic human pathogen. Endospores are highly specialized, metabolically dormant cell types that are resistant to extreme environmental conditions, including heat, dehydration and other physical stresses. B. cereus can enter a range of environments, and can in its spore form, survive harsh conditions. If these conditions become favorable, spores can germinate and grow out and reach considerable numbers in a range of environments including processed foods. Certainly the last decade, when consumer preferences have shifted to mildly processed food, new opportunities arose for spore-forming spoilage and pathogenic organisms. Only rigorous methods have been shown to be capable of destroying all spores present in food, thus a shift toward e.g., milder heat preservation strategies, may result in low but significant amounts of viable spores in food products. Hence, the need for a mild spore destruction strategy is eminent including control of spore outgrowth. Consequently, there is a large interest in triggering spore germination in foodstuffs, since germinated spores have lost the extreme resistance of dormant spores and are relatively easy to kill. Another option could be to prevent germination so that no dangerous levels can be reached. This contribution will focus on germination and outgrowth characteristics of B. cereus and other members of the B. cereus group, providing an overview of the niches these spore-formers can occupy, the signals that trigger germination, and how B. cereus copes with these wake-up calls in different environments including foods, during food processing and upon interaction with the human host.     

2014~2015年吉林省食源性致病菌监测结果分析

目的 了解吉林省食源性致病菌的污染情况, 确定高危食品的种类和分布。方法 依据《2014年国家食品污染物和有害物质因素风险监测工作手册》中的方法, 对2014~2015年市售7类食品中的沙门氏菌、铜绿假单胞菌、致泻大肠埃希氏菌和空肠弯曲菌进行检测, 并对检测结果进行统计分析。结果 2014~2015年监测的4067份样品中, 检出阳性致病菌67株, 总体检出率为1.65%。其中, 沙门氏菌27株、铜绿假单胞菌20株、致泻大肠埃希氏菌1株、空肠弯曲菌19株。桶装饮用水污染最为严重, 检出率为20.62%; 肉与肉制品检出率为3.72%, 散装和预包装食品中食源性疾病菌的检出率分别为1.55%和1.96%。结论 吉林省市售食品存在不同程度的食源性致病菌污染, 其中桶装饮用水、肉制品为主要污染食品类别, 卫生部门应加强对其的监督和管理。