蜡样芽孢杆菌及其芽孢的杀菌技术和动力学研究进展

蜡样芽孢杆菌是易造成食源性疾病爆发的污染菌之一。本文重点介绍了蜡样芽孢杆菌的几种新型食品杀菌技术及几种常用的动力学模型,其中,新型杀菌技术包括:高温瞬时杀菌、射频加热、高静压以及高压脉冲电场等;动力学模型包括:线性和非线性模型。并对蜡样芽孢杆菌及其芽孢在不同介质、杀菌方法及条件的杀菌动力学模型参数分别进行总结。因此认为传统均匀加热的杀菌动力学为线性模型,而高新技术的杀菌动力学通常为非线性的,非线性模型中最常用的两个模型为Weibull模型和Log-logistic模型。      

米饭中蜡样芽孢杆菌剂量效应模型的构建

目的建立有效的米饭蜡样芽孢杆菌剂量效应模型。方法调研并选用2001-2011年我国9起米饭中蜡样芽孢杆菌导致食物中毒的数据,基于指数模型、泊松模型、对数模型、威布模型等及其修正形式分别构建了米饭中蜡样芽孢杆菌剂量效应模型。结果修正的指数模型、对数概率模型和Gamma威布模型三者在拟合效果上显著优于其他模型(R20.70),拟合曲线外延至低剂量预测中毒率时,Gamma威布模型低于前两者,进一步的数学检验表明,Gamma威布模型准确因子(Af=1.40)优于前两者,偏差因子(Bf)和预测标准误差(SEP)相近或略高于前两者。结论建议选用Gamma威布模型作为米饭中蜡样芽孢杆菌最优的剂量效应模型用于蜡样芽孢杆菌风险评估体系中的危害特征分析。     

Modelling the overall effect of pH on the apparent heat resistance of Bacillus cereus spores.

A simple overall model is proposed to describe the effect of both the pH of the heating menstruum and the pH of the recovery medium on the apparent spore heat resistance of Bacillus cereus. Applied to foods making up both heating and recovery media, the model can be reduced to only two parameters. Its goodness of fit and its robustness enable it to be applied to the optimisation of heat treatments. However. further experiments should be undertaken to validate the model for other species and to determine the parameters related to reference species such as Clostridium botulinum.     

胁迫因素对玻璃表面蜡样芽孢杆菌菌膜形成的影响分析

以食源性致病菌蜡样芽孢杆菌形成的菌膜为研究对象,模拟食品加工过程中温度胁迫、酸碱胁迫、营养胁迫、渗透胁迫、防腐剂胁迫等外源条件,采用超声波平板菌落计数玻璃表面菌膜形成量,结晶紫染色法观察菌膜在玻璃表面的生长形态。结果表明:温度胁迫下,低温4℃、高温50℃均能形成菌膜且随着温度升高菌膜形成量先升高后降低,温度30℃时菌膜形成量最大;酸碱胁迫下,p H小于或大于7.0时,菌膜的形成受到抑制,p H7.0时菌膜形成量最大;营养胁迫下,添加葡萄糖有利于菌膜形成,添加4%葡萄糖有明显的促进菌膜形成的效果;渗透胁迫下,低浓度的氯化钠对蜡样芽孢杆菌菌膜形成有促进作用,高浓度的氯化钠对菌膜形成有抑制作用,添加0.5%氯化钠有明显的促进菌膜形成的效果;防腐胁迫下,食品防腐剂浓度为0.15%高于浓度为0.10%时的菌膜形成量,在食品加工中不能仅凭加入食品防腐剂而疏忽对菌膜的控制。      

大蒜提取物对蜡样芽孢杆菌抑制效果的研究

该文采用抑菌圈法研究了大蒜的水提取物、乙醇提取物和酸性水溶液的提取物对蜡样芽孢杆菌的抑制作用.结果表明大蒜的乙醇提取物的抑菌效果好过水提取物,酸性的水溶液提取物效果最好,可以较好地控制蜡样芽孢杆菌的生长,有较好的应用前景.     

云南木姜子提取物对蜡样芽孢杆菌抑菌作用的研究

目的 研究云南木姜子(Yunnan Litsea cubeba)的抑菌活性及抑菌稳定性。方法 用乙醇对云南木姜子果实进行提取并分别用石油醚、氯仿、乙酸乙酯、正丁醇进行萃取。比较不同萃取相对蜡样芽孢杆菌的抑制作用,并通过热处理、酸碱处理、紫外照射、金属离子处理、糖和盐处理对其稳定性进行考察。结果 云南木姜子提取物对蜡样芽孢杆菌具有良好的抑菌作用,其活性成分主要分布于乙酸乙酯相,其对蜡样芽孢杆菌的最小抑菌浓度为0.08 mg/mL;云南木姜子乙酸乙酯萃取相经紫外线照射、酸碱处理和不同温度处理仍表现出良好的稳定性,盐和糖处理条件使其对蜡样芽孢杆菌的抑菌活性增强,对于金属离子处理,Mg²⁺使其对蜡样芽孢杆菌的抑菌活性提高,Fe³⁺、Fe²⁺、Al³⁺和Ca²⁺等使其抑菌活性降低。结论 云南木姜子提取物具有良好的抑菌活性,温度、紫外和pH对其抑菌成分的稳定性有较小的影响,金属离子、糖和盐浓度对其抑菌活性影响较大。因此可考虑将云南木姜子作为一种天然植物源防腐剂,它在保鲜方面具有良好的开发和...     

即时食品蜡样芽孢杆菌快速检测标准曲线模型的研究

本实验研究建立了一种即时食品蜡样芽孢杆菌快速检测模型.基于实时光电检测技术,将蜡样芽孢杆菌标准菌株(CICC10041)菌液进行7次10倍递增稀释,每个稀释度进行国标法和实时光电法2种方法5次重复测定,获得35组一一对应的数据,以国标法计数结果的对数值为纵坐标,以实时光电法相应稀释度的DT值为横坐标,建立标准曲线模型,...     

基于3种模型的市售腐乳中蜡样芽胞杆菌风险的比较性评估研究

目的应用修正指数模型、对数概率模型和Gamma威布模型对某市市售腐乳中蜡样芽胞杆菌进行定量风险比较评估研究。方法利用某市抽检数据,获得市售腐乳中蜡样芽胞杆菌的初始污染水平,分别按照修正的指数模型、对数概率模型和Gamma威布模型计算市售腐乳蜡样芽胞杆菌的风险。结果使用市售腐乳蜡样芽胞杆菌的初始污染水平均值作为消费量,Gamma威布模型计算所得风险略低于另外两个模型,使用初始污染水平最高值作为消费量,Gamma威布模型计算所得风险略高于另外两个模型。结论本研究以蜡样芽胞杆菌风险评估为样本,为其他微生物开展风险评估提供了研究方法和思路。     

Influence of recovery conditions on apparent heat resistance of Bacillus stearothermophilus spores

The effects of post-treatment environmental factors on the heat resistance of Bacillus stearothermophilus spores (ATCC 12980, 7953, 15951 and 15952) were investigated. Nutrient Agar (NA), Antibiotic Assay Medium (AAM), Dextrose Tryptone Agar (DTA) and Tryptic Soy Agar (TSA) with Ca^{2+ added to a final concentration of 100 p.p.m. were used as recovery media. No significant differences were seen between D-values obtained except in the case of strain 12980 when comparing TSA with the other media and for strain 7953 comparing AAM and DTA. The optimum incubation temperature was slightly lower for heated than for unheated spores of} each strain, although, in general, 50 °C was adequate. Higher D-values were obtained at 50–55 °C. The effects of the pH of the medium in the range 5.0–7.0 and the addition of starch and phosphate on heat resistance have also been investigated. Maximum colony counts of heated spores were obtained at pH 7.0 and decreased as pH fell. D-values were significantly lower at pH ≤ 5.5. Increasing the concentration of phosphate in the recovery medium from 0 to 0.2% resulted in a progressive decrease in spore recovery and D-values. The addition of starch improved recoverability. The z-values obtained for the four strains studied under the different recovery conditions were similar with a mean value of 7.58 °C ± 0.28.     

Model for Combined Effects of Temperature, pH and Water Activity on Thermal Inactivation of Bacillus cereus Spores

Initially, the effect of water activity (a_w) on heat resistance of Bacillus cereus spores (decimal reduction time) was investigated. A linear relationship was found between log D and 1-a_w. The combined effects of temperature (85-105°C), pH (4.5-6.5) and water activity (0.80-1) were then studied. A four parameter model was fitted to the data. This model appeared to be parsimonious with each parameter having a biological significance. Interactions between factors were observed but they accounted for <2.4% of the total variation and they were not taken into account by the model.     

Bacillus cereus, the causative agent of an emetic type of food-borne illness

Bacillus cereus is the causative agent of two distinct forms of gastroenteritic disease connected to food-poisoning. It produces one emesis-causing toxin and three enterotoxins that elicit diarrhea. Due to changing lifestyles and eating habits, B. cereus is responsible for an increasing number of food-borne diseases in the industrial world. In the past, most studies concentrated on the diarrhoeal type of food-borne disease, while less attention has been given to the emetic type of the disease. The toxins involved in the diarrhoeal syndrome are well-known and detection methods are commercially available, whereas diagnostic methods for the emetic type of disease have been limited. Only recently, progress has been made in developing identification methods for emetic B. cereus and its corresponding toxin. We will summarize the data available for the emetic type of the disease and discuss some new insights in emetic strain characteristics, diagnosis, and toxin synthesis.     

Synergistic effects of high pressure processing and slightly acidic electrolysed water on the inactivation of Bacillus cereus spores

Bacillus spores are concerns for their resistance to heat, high pressure processing (HPP), and disinfectants. We examined the effects of HPP and slightly acidic electrolysed water (SAEW) on inactivation of B. cereus spores. Spores' suspensions were prepared with 2‐(N‐morpholino) ethanesulfonic acid (MES) buffer or SAEW with available chlorine content (ACC) of 24, 35, 44 or 55 mg L^?1, and then subjected to HPP. The individual effects of HPP or SAEW on spores were negligible (<1.0 log CFU mL^?1). With factorial design and anova analysis, HPP + SAEW treatment was shown to have significantly positive effects on spores’ inactivation. The optimal conditions were 300 MPa HPP + SAEW with 44 mg L^?1 ACC or 200 MPa HPP + SAEW with 44 mg L^?1 ACC + 500 MPa HPP, producing reductions of 3.27 and 3.99 log CFU mL^?1, respectively. HPP + SAEW have potentials to serve as two effective hurdle techniques for inactivating B. cereus spores.     

Original article: Modelling the effects of food ingredients and pH on high‐pressure processing inactivation of Bacillus cereus spores: a laboratorial study

The combination of high pressure and heat on Bacillus cereus spores in food matrix was investigated with the purpose of achieving a predictive model of microbial inactivation. The high‐pressure processing (HPP) conditions were fixed at 540 MPa and 71 °C for 16.8 min, which were determined as the optimum conditions considering six‐log‐cycle reductions of B. cereus spores. The effects of soybean protein, sucrose, soybean oil and pH on the inactivation of B. cereus spores by HPP were evaluated, and a quadratic predictive model for the effects of food ingredients and pH on the reductions of B. cereus spores by HPP was built using response surface methodology. The experimental results showed that soybean protein, sucrose and pH significantly affected the reductions of B. cereus spores. The predictive model is significant, because the level of significance was P < 0.0001 and the calculated F‐value is much greater than the tabulated F‐value. The adequacy of the predictive model equation was verified effectively using the experimental test data that were not used in the development of the model.     

Extended shelf life milk processing: Effect of simulated cleaning in place on the germination and attachment of Bacillus cereus spores

The effect of simulated cleaning in place (CIP) was determined on the structure, attachment and growth of Bacillus cereus spores isolated from raw milk and biofilms in filler nozzles from extended shelf life (ESL) milk processing lines. Simulated CIP treatment structurally affected >98% of B. cereus spores, while 0.1% remained intact. Following simulated CIP treatment, B. cereus spores were able to attach to stainless steel coupons and form biofilms. B. cereus spores were capable of germination and growth under refrigerated conditions for more than 28 days. Contamination with B. cereus spores may lead to a reduced shelf life and potentially be a safety risk in ESL milk with a prolonged shelf life.     

食源性蜡样芽孢杆菌的危害及其检测方法研究进展

蜡样芽孢杆菌是一种常见的食源性致病菌,可通过污染乳制品、米饭、散装熟肉制品和豆制品等食品引起婴幼儿及成人食物中毒。采用准确、高效的蜡样芽孢杆菌检测方法,是预防食源性蜡样芽孢杆菌病及食品安全质量控制的关键。蜡样芽孢杆菌检测方法主要包括细菌培养分离鉴定法、免疫学检测方法和核酸检测方法等。本文总结了各类检测方法的核心技术特征和应用实例,为食源性蜡样芽孢杆菌的快速检测方法的研发和使用提供思路。     

吉林省2011~2015年食品中蜡样芽胞杆菌污染监测数据分析

目的为了掌握吉林省市售食品中蜡样芽胞杆菌污染情况,为预防食源性疾病及保障食品安全工作提供科学研究数据。方法：根据GBT4789.14-2014中华人民共和国食品安全国家标准 蜡样芽胞杆菌检验方法对2011-2015年的1693份样品进行蜡样芽孢杆菌监测。结果 1693份样品中检出蜡样芽胞杆菌557株,总检出率为32.90%。2015年阳性检出率较其他年份显著升高。乳与乳制品污染最为严重,其次为餐饮食品和婴幼儿配方食品,其检出率分别为39.45%、31.49%和31.09%。餐饮服务环节与流通环节、散装与预包装等因素对阳性检出率无显著性差别。结论五年间吉林省食品中蜡样芽胞杆菌均存在严重污染, 2015年该菌污染率显著升高。相关部门应加强重视,加大监管力度,预防食源性疾病的发生。     

The ability of Schisandra chinensis fruit to inhibit the growth of foodborne pathogenic bacteria and the viability and heat resistance of Bacillus cereus spores

The objective of this study was to investigate the influence of Schisandra chinensis fruit on the growth of spoilage and pathogenic bacteria and on the viability and heat resistance of Bacillus cereus spores. Schisandra chinensis fruit was extracted with one of three different solvents (50% ethanol, 100% ethanol and distilled water), and the extracts exhibited antimicrobial activity against all the bacteria tested. Particularly, the ethanol extracts of S. chinensis fruit had the strongest activity, in a concentration‐dependent manner. Fractionation of extracts by ion chromatography revealed that the antimicrobial activity of S. chinensis fruit is mainly due to organic acids such as citric acid and malic acid. Meanwhile, S. chinensis fruit extract (10%) significantly reduced the viability and heat resistance of B. cereus spores. Therefore, this study suggests that S. chinensis fruit extract has potential as a natural food preservative and/or sanitising agent for the reduction of spoilage and pathogenic contamination.     

婴幼儿配方乳粉及婴幼儿米粉中的蜡样芽胞杆菌流行情况、耐药性及分子特征研究

目的 了解流通环节市售婴幼儿配方乳粉和婴幼儿米粉中的蜡样芽胞杆菌流行情况、抗生素耐药性和毒力基因等分子特征。方法 采用GB 4789.14—2014《食品卫生微生物学检验 蜡样芽胞杆菌检验》对样品中的蜡样芽胞杆菌进行检测与生化鉴定。进一步通过抗生素敏感实验和全基因组测序对11株代表性分离株进行研究,获得耐药表型及耐药、毒力基因等分子特征信息。结果 婴幼儿配方乳粉和婴幼儿米粉中蜡样芽胞杆菌的检出率分别为11.97%（56/468）和20.74%（28/135）。11株代表性蜡样芽胞杆菌均为多重耐药菌株,全基因组测序结果发现11株分离株共携带8个耐药基因和14个毒力基因,其中主要携带磷霉素、β-内酰胺类抗生素抗性基因,以及肠毒素基因（hbl和nhe）,另发现1株携带ces基因簇蜡样芽胞杆菌菌株。11株分离株具有遗传多样性,11株分离株分属10个ST型。结论 婴幼儿配方乳粉和婴幼儿米粉中的蜡样芽胞杆菌检出率较低,但代表菌株的耐药谱和遗传特征具有多样性,应进一步加强监测及采取有效措施进行控制,以保障相关食品的安全性。     

环境因子交互作用下蜡样芽孢杆菌生长/非生长界面模型的建立与评价

本文旨在建立一种生长/非生长界面模型来预测蜡样芽胞杆菌在环境因子交互作用下的生长概率。选取五株蜡样芽孢杆菌菌株的混合菌株作为研究对象,研究温度、pH、Aw对混合菌株生长概率的交互影响。获得的生长/非生长实验数据用logistic回归方程拟合,建立了环境因子交互作用下蜡样芽孢杆菌生长/非生长界面模型。实验采取部分析因设计方案,选定80%的实验数据用做模型的拟合,20%的数据用做模型的验证。并从已发表的文献中选取30个数据作为测试集,通过比较预测值和观察值来检测已建模型的适用度。实验结果表明,训练集的一致性指数为0.991,验证集的一致率为0.988,说明模型对同类数据预测准确度高;同时模型的R2-Nagelkerke值也较高,为0.949;Hosmer-Lemeshow检验中的χ2=0.012,P=1,logistic回归模型拟合度较高。模型对测试集的预测准确率达83.3%,该模型对所选数据具有较高的预测能力,说明模型具有较广的适用范围。     

湿粉类制品蜡样芽胞杆菌污染风险及控制研究

目的 以广州市为例分析湿粉类制品蜡样芽胞杆菌污染情况和生产加工过程的风险点,提出相应的控制措施.方法 选择广州市范围生产湿粉类制品的生产单位,采集生产环节和销售环节样品及同批次产品生产使用的原料,对蜡样芽胞杆菌进行定量检测.结果 共采集32份出厂的湿粉类制品、139份市售湿粉类制品、32份原料大米、5份小麦淀粉、3份玉...