武汉市售茶中2 种食源性致病菌的检测与分析

为了解市售茶叶中菌落总数和2 种食源性致病菌（蜡样芽孢杆菌和克罗诺杆菌）的检出情况,根据国标对武汉地区市售的46 份茶叶样品进行菌落总数和2 种食源性致病菌的初步分离和鉴定,分别用16S rDNA内转录间隔区-聚合酶链式反应方法鉴别蜡样芽孢杆菌,用16S rDNA和fusA序列分析对疑似克罗诺杆菌的分离株进行鉴定,进而比较和分析不同产地和类别间微生物的检出情况。结果发现,蜡样芽孢杆菌在市售茶叶中检出率极高,达97.9%,而且其数量约占细菌总数的6.0%。鉴定出3 株阪崎克罗诺杆菌（Cronobacter）,其检出率达6.5%,仅占细菌总数的0.1%～3.2%。花草茶中细菌总数最高,也是唯一检出克罗诺杆菌的茶类;发酵茶中蜡样芽孢杆菌数量最高,均超过1 100 MPN/g。不同产地茶叶在这3 个微生物指标上有显著差异。当茶及其深加工产品和其他食品原辅料混搭成新产品时,这2 种食源性致病菌可能带来风险隐患。     

贵州市售腐乳蜡样芽孢杆菌污染研究分析

为了解贵州市售腐乳中蜡样芽孢杆菌的污染情况,以及市售腐乳中蜡样芽胞杆菌的污染量的规律,依据国家标准GB 4789.14《蜡样芽胞杆菌的检测》,用甘露醇卵黄多粘菌素琼脂（MYP）结合生化鉴定的方法,对贵州市售的50个腐乳进行检测与鉴定。结果表明：贵州市售腐乳中蜡样芽孢杆菌的检出率为74%,其中超过风险值的有3份,分别为1.9×105 CFU/g 、2.1×106 CFU/g、8.4×105 CFU/g;检出量超103有23份。对50个样品分类分析发现,腐乳的不同产地、不同货架期及不同腐乳种类的蜡样芽胞杆菌检测量有显著差异（P<0.05）;不同生产季节的蜡样芽胞杆菌检测量没有差异（P>0.5）;即抽检的50个样品,其产地、品种、货架期会影响蜡样芽胞杆菌的污染量。对贵州市售腐乳的蜡样芽孢杆菌的检测得出结论：贵州市售腐乳存在一定的蜡样芽孢杆菌引起食物中毒的风险。     

豆豉中蜡样芽孢杆菌污染情况分析

对来自武汉市售的50份豆豉样品进行微生物污染情况调查,主要检测豆豉中蜡样芽孢杆菌,以及菌落总数、霉菌与酵母和芽孢杆菌数.结果表明,豆豉中蜡样芽孢杆菌检出率很高,为94.0％,阳性样品含菌量为3.6c fu/g～1100cfu/g,几何均数为75.8cfu/g.不同地区的豆豉中蜡样芽孢杆菌的几何均数不同(21.2c fu/g～466.0cfu/g).本调查分析对我国豆豉中蜡样芽孢杆菌污染的溯源奠定基础.     

细菌型豆豉蜡样芽孢杆菌的动态变化研究

采用传统分离鉴定法对细菌型豆豉不同发酵时期蜡样芽孢杆菌污染情况进行动态检测。结果表明,自然发酵过程中,蜡样芽孢杆菌最高达到2.3×104 CFU/g;纯种强化发酵过程中蜡样芽孢杆菌最高达1.1×103 CFU/g,自然发酵豆豉的蜡样芽孢杆菌含量高于纯种强化发酵。豆豉成品中总蜡样芽孢杆菌数量均＜105 CFU/g,短期内不存在食品安全问题。经分析,豆豉成品中蜡样芽孢杆菌主要来源于前发酵豆豉。     

三类传统发酵食品中蜡样芽孢杆菌的污染状况研究

为探究辣椒酱、酸汤、毛豆腐三类传统发酵食品的蜡样芽孢杆菌（Bacillus cereus）污染状况,采用国标GB 4789.14—2014《食品微生物学检验蜡样芽孢杆菌检验》方法测定样品的污染菌数及分离菌株的生理生化特征,并通过聚合酶链式反应（PCR）方法探究分离菌株的毒力基因谱和多样性。结果表明,5个辣椒酱及4个酸汤样品的蜡样芽孢杆菌检出率均为100%,菌数在3.6～460 MPN/g之间。而7个毛豆腐的蜡样芽孢杆菌检出率为28.57%,其中2个夏季样品的蜡样芽孢杆菌菌数>7 lg(CFU/g),5个秋季样品未检出蜡样芽孢杆菌,污染差异可能与气温变化、运输方式有关,需要实地采样并进行季节性分析。从三类样品中分离的94个菌株均符合蜡样芽孢杆菌生理生化特征,毒力基因均为腹泻型,且菌株多样性与样品差异性有关。综上,蜡样芽孢杆菌的污染特性具有明显的样品差异性,可能与发酵食品的原料、发酵工艺相关。     

植物乳杆菌JY-22细菌素粗提物在鲢鱼鱼丸保鲜中的应用

应用植物乳杆菌JY-22细菌素粗提物对鲢鱼鱼丸中地衣芽孢杆菌和蜡样芽孢杆菌进行抑菌保鲜研究,以感官、理化和细菌学指标对鲢鱼鱼丸产品质量进行安全性评价。结果表明：添加JY-22细菌素粗提物可以改善鲢鱼鱼丸感官品质,能有效抑制鲢鱼鱼丸中芽孢杆菌的生长,第21天时,添加0.6 倍最小抑菌浓度（minimum inhibitory concentration,MIC）JY-22细菌素粗提物处理组比单独添加地衣芽孢杆菌和蜡样芽孢杆菌处理组的菌落数分别减少1.92（lg（CFU/g））和1.00（lg（CFU/g））;添加JY-22细菌素粗提物可使鲢鱼鱼丸在贮藏过程中pH值下降速度变缓,一定程度上会降低鱼丸白度,但对弹性影响不明显,添加0.6 MIC的JY-22细菌素粗提物能使产品保质期至少延长3 d。菌株JY-22细菌素粗提物可有效控制鲢鱼鱼丸中芽孢杆菌的生长繁殖,对产品具有良好的保鲜效果。     

即食淡腌草鱼制品品质特征和细菌菌群组成研究

对即食淡腌草鱼制品感官、理化、微生物学品质及残存细菌进行定性和定量研究,并对潜在病原菌安全性进行评价。结果表明:产品水分含量为46.10%±8.15%,Aw为0.95±0.02,pH6.23±0.15,盐分3.47%±2.31%;有氧菌落总数为(4.66±2.04)lgCFU/g,厌氧菌落总数为<10CFU/g,耐热菌落总数(2.39±1.03)lgCFU/g,蜡样芽孢杆菌(1.60±0.54)lgCFU/g,金黄色葡萄球菌<10CFU/g。分离获得240株菌,细菌菌群主要有玫瑰小球菌(30.8%)、芽孢杆菌(27.5%)、葡萄球菌(23.8%),并出现少量的棒状杆菌(5.4%)。产品中残存有一定数量的蜡样芽孢杆菌和葡萄球菌,对其致病性潜在危害有待进一步研究。     

低温肉制品中微生物检测及优势菌群的鉴定和分析

对市售某3个品牌的在架真空包装冷藏肉制品样品,进行嗜冷菌和中温菌微生物检测,利用16SrDNA序列分析鉴定其中优势菌群.结果表明:10-3稀释度检测的菌落总数总是高于10-1和10-2稀释度的菌落总数.说明肉制品中防腐剂的浓度在低稀释度下仍然能抑制微生物生长,干扰细菌总数的测定,造成误判.样品中优势菌属主要有3类:芽孢杆菌属Bacillus、假单胞菌属Pseudomonas、葡萄球菌属Staphylococcus.条件致病菌蜡样芽孢杆菌和葡萄球菌在3个品牌产品中均有较高检出率(13.3％～24.4％),而且均能在10℃和30℃生长,具有潜在致病性.     

哈尔滨市道里区蔬菜基地生菜和水土环境中常见细菌污染调查分析

目的：了解哈尔滨市生菜和生菜生长水土环境中常见细菌的污染情况,为调查和预防生菜中潜在的风险因子提供参考。方法：采集2019—2021年哈尔滨市周边3个生菜种植基地生菜样品200份,水土环境样品70份,参照相关国家标准,对大肠菌群、沙门氏菌、金黄色葡萄球菌和蜡样芽孢杆菌进行检测。用SPSS软件进行相关统计分析。结果：生菜及环境样品中,沙门氏菌和金黄色葡萄球菌均未检出,土壤中大肠菌群与蜡样芽孢杆菌检出率均高于生菜（p<0.05）,紫叶生菜中蜡样芽孢杆菌检出率高于绿叶生菜（p<0.05）;绿叶生菜中大肠菌群检出率2020年高于2019年和2021年（p<0.05）,蜡样芽孢杆菌检出率2020年高于2021年（p<0.05）和2019年（p<0.05）。结论：生菜和水土环境中分别检出了大肠菌群和蜡样芽孢杆菌,生食生菜具有一定的安全隐患,相应的细菌污染来源值得关注,建议从生菜生产源头加强产地安全监管,保障生菜质量安全。     

95℃水雾炖煮工艺条件下燕窝制品微生物安全风险评价

为了研究95℃水雾炖煮工艺对燕窝制品生产过程中微生物的消减效果,并评价产品储藏和运输过程中微生物的安全性,测定了炖煮前后样品微生物数量变化以及在不同贮藏和运输温度下燕窝产品中微生物菌落数量变化规律,并通过分子生物学方法鉴定燕窝成品加速腐败样品中所分离微生物的种类。结果显示, 95℃水雾炖煮条件下微生物杀菌效果最高可达5 lg (CFU/g),在低于8℃温度条件下贮存20 d内,燕窝成品中菌落总数均≤1 lg (CFU/g),大肠菌群<10 MPN/g,沙门氏菌未检出/25 g,金黄色葡萄球菌和霉菌均<10 CFU/g。另外,燕窝成品加速试验中微生物培养分纯菌株分子鉴定结果显示,燕窝产品加速试验中的微生物为芽孢杆菌属和葡萄球菌属细菌。经系统发育分析,所分纯微生物为弯曲芽孢杆菌、巨大芽孢杆菌、南海假芽孢杆菌和沃氏葡萄球菌,该类细菌通常情况下不会引起人类或者动物疾病,分析结果间接证明了水雾炖煮燕窝在生产过程中的安全性。此研究有利于了解水雾炖煮工艺在燕窝生产中应用的安全性,并为保障低温灭菌短保质期燕窝品质安全提供理论依据。     

Comparing the mannitol-egg yolk-polymyxin agar plating method with the three-tube most-probable-number method for enumeration of Bacillus cereus spores in raw and high-temperature, short-time pasteurized milk

The U.S. Food and Drug Administration's Bacteriological Analytical Manual recommends two enumeration methods for Bacillus cereus: (i) standard plate count method with mannitol-egg yolk-polymyxin (MYP) agar and (ii) a most-probable-number (MPN) method with tryptic soy broth (TSB) supplemented with 0.1% polymyxin sulfate. This study compared the effectiveness of MYP and MPN methods for detecting and enumerating B. cereus in raw and high-temperature, short-time pasteurized skim (0.5%), 2%, and whole (3.5%) bovine milk stored at 4°C for 96 h. Each milk sample was inoculated with B. cereus EZ-Spores and sampled at 0, 48, and 96 h after inoculation. There were no differences (P > 0.05) in B. cereus populations among sampling times for all milk types, so data were pooled to obtain overall mean values for each treatment. The overall B. cereus population mean of pooled sampling times for the MPN method (2.59 log CFU/ml) was greater (P < 0.05) than that for the MYP plate count method (1.89 log CFU/ml). B. cereus populations in the inoculated milk samples ranged from 2.36 to 3.46 and 2.66 to 3.58 log CFU/ml for inoculated milk treatments for the MYP plate count and MPN methods, respectively, which is below the level necessary for toxin production. The MPN method recovered more B. cereus, which makes it useful for validation research. However, the MYP plate count method for enumeration of B. cereus also had advantages, including its ease of use and faster time to results (2 versus 5 days for MPN).     

我国市售婴儿配方乳粉中蜡样芽胞杆菌污染及其毒力基因调查

目的了解国内市售婴儿配方乳粉中蜡样芽胞杆菌污染及毒力基因分布情况。方法采用MPN法定量检测婴儿配方乳粉中的蜡样芽胞杆菌,在对分离菌株正确鉴定的基础上,开展腹泻型和呕吐型毒素产生相关毒力基因的分布研究。结果 135份婴儿配方乳粉中有57份检出蜡样芽胞杆菌,检出率为42.22%。平均污染水平为7.14 MPN/g。国产产品蜡样芽胞杆菌污染较进口产品重,网售产品较超市销售产品重,差异有统计学意义(P0.05)。共发现24种蜡样芽胞杆菌毒力基因携带模式,其中nhe基因携带率最高,达92.98%(53/57),其次为ent FM基因(71.93%),70.18%(40/57)的菌株同时携带nhe和ent FM基因。亚型分型结果显示nhe A、nhe B和nhe C基因的携带率分别为88.72%、88.72%和49.12%。溶血素BL基因携带率分别为hbl A 24.56%、hbl C 22.81%和hbl D 17.54%,cyt K基因携带率为22.81%。有8株菌既携带nhe的3个基因又携带hbl的3个基因。结论我国市售婴儿配方乳粉蜡样芽胞杆菌污染较重,分离到的蜡样芽胞杆菌菌株普遍携带毒力基因,建议加强对婴儿配方乳粉中蜡样芽胞杆菌污染的监管,并开展膳食暴露该菌对婴儿健康影响的风险评估,为制定婴儿配方乳粉中蜡样芽胞杆菌的限量标准提供依据。     

2016~2018年市售242件婴幼儿米粉微生物污染情况调查

目的 了解玉溪市售国产婴幼儿营养米粉的卫生状况。方法 采用国家标准方法对242件玉溪市市售的婴幼儿营养米粉进行细菌总数、大肠菌群、肠杆菌科、克罗诺杆菌属及蜡样芽胞杆菌检测分析。结果 本次采集的婴幼儿米粉样品的合格率为74.38%; 大肠菌群指标均未超标; 7件米粉样品细菌总数超标, 占比8.54%; 58件样品检出克罗诺杆菌属, 阳性率为23.97%; 10件样品检出蜡样芽胞杆菌, 阳性检出率为4.13%。一季度生产的样品合格率最低, 产自中国福建、广西、湖南、浙江及美国、西班牙、英国、日本和欧洲其他地区的米粉样品合格率最高, 采自零售店及包装形式为散装的样品合格率最低。结论 2016至2018年玉溪市市售婴幼儿米粉中部分样品细菌总数超标, 存在克罗诺杆菌属污染, 可能会导致婴幼儿感染。     

Bacterial contamination of ready-to-eat foods and fresh products in retail shops and food factories.

Raw vegetables cut for salad, cooked salad, cooked rice, boiled noodles, bean curd, and cooked Japanese foods were purchased in 27 retail shops in Tokyo. Intact vegetables before being processed and ready-to-eat fresh salad products were obtained from two food factories located in the suburbs of Tokyo. Two hundred thirty-eight retail samples, 137 samples of intact vegetables, and 159 samples of fresh products were examined for aerobic plate count (APC), coliforms, Escherichia coli, Listeria spp., Staphylococcus aureus, and Bacillus cereus. The APC of retail foods were 2.1 to 5.7 log CFU/g, and the range for the coliforms was 0.1 to 2.3 log CFU/g. The APC and coliform values showed that the raw vegetables cut for salad were the most heavily contaminated among the six kinds of ready-to-eat foods examined. Although L. monocytogenes was not detected, two samples of raw vegetables and five kinds of cooked foods yielded Listeria spp. S. aureus was detected in one sample of Japanese cooked food. The APC of the intact vegetables were 2.9 to 7.3 log CFU/g upon arrival and 2.2 to 7.2 log CFU/g after 3 days storage at 10 degrees C. The APC of the fresh products were 3.4 to 7.6 log CFU/g upon arrival and 4.7 to 8.7 log CFU/g after 3 days storage at 10 degrees C. The isolation rates for coliforms were 6.1 to 50% for intact vegetables and 50 to 66.7% for fresh products. E. coli was detected only in the fresh products. B. cereus was isolated from 20.1% (17 of 81) of the intact vegetables and 9.2% (8 of 87) of the fresh products.     

石家庄市市售婴幼儿食品中蜡样芽胞杆菌的监测及溶血素基因的分析

了解目前市售婴幼儿配方奶粉、谷基辅助食品样品中蜡样芽胞杆菌的污染及其毒素基因的携带情况。方法 采集石家庄市23个区县市售婴幼儿配方粉、谷基辅助食品共399份,依照国家标准 GB/T 4789.14—2003《食品卫生微生物学检验 蜡样芽胞杆菌检验》和《食源性致病菌监测工作手册》进行蜡样芽胞杆菌检测并计数,应用荧光PCR方法检测蜡样分离株的溶血素基因和非溶血素基因。结果 399份样品中蜡样芽胞杆菌检出85份,其中婴幼儿配方奶粉检出36份,检出率22.8%(36/158);谷基辅助食品检出49份,检出率20.3%(49/241)。85份阳性样品中有48份呈溶血素基因阳性,检出率56.5%,非溶血素基因均为阴性。结论 婴幼儿食品中蜡样芽胞杆菌的污染较严重,存在潜在的食品风险。分析结果可为婴幼儿食品卫生学检验标准及监督管理等方面提供参考。     

Levels and enterotoxigenicity of Clostridium perfringens in pozole, tamales, and birria

A quantitative survey of Clostridium perfringens in typical foods served at local restaurants was conducted for 18 months in Guadalajara, Mexico. A total of 151 samples, including goat's birria (50), pozole (50), and beef tamales (51), were collected from small restaurants in Guadalajara. Samples were tested for C. perfringens by the most probable number (MPN) method and for mesophilic aerobic plate counts (MAPCs) and coliform, yeast, and mold counts by plate count methods. Isolates confirmed as C. perfringens were further sporulated and tested for cytotoxic or cytotonic effect against Vero cells as an indication of enterotoxin production. C. perfringens was detected in 78 (52%) of all samples at concentrations that ranged from 2.3 to 5.4 log MPN/g. Average MAPCs were 1.3 to 2.7 log CFU/g, depending on the type of dish. Coliform counts ranged from less than 1.0 to 1.5 CFU/g, and yeast and mold counts were less than 1.0 log CFU/g in all cases. A total of 118 isolates of C. perfringens were tested for enterotoxic effect on Vero cells; 82 (70%) showed activity against Vero cells. Of them, 31 isolates induced cell lysis, indicating cytotoxic effect; 41 induced cell elongation, indicating cytotonic effect; and 10 produced both cytotoxic and cytotonic effect. Dilution of the bacterial filtrates that were still producing an effect on Vero cells ranged from 1:80 to 1:5,120. These results underscore the importance of determining enterotoxigenicity when testing for C. perfringens in foods.     

Detection and distribution of food-borne bacteria in ready-to-eat foods in Korea

In this study, the contamination levels of total aerobic plate counts, Escherichia coli and various pathogenic bacteria in ready-to-eat (RTE) foods were investigated in Korea. A total of 634 samples were purchased randomly from 47 stores located in 3 different provinces. The aerobic plate count levels of RTE occurred in a relatively wide range, of 1.0–7.9 log CFU/g. E. coli and Listeria monocytogenes were detected in only 2 samples in the qualitative test. Staphylococcus aureus and Bacillus cereus were detected in 12.3 and 12.6% of the samples at levels up to 1 log CFU/g. These results demonstrate that RTE foods in Korea can be contaminated by a variety of pathogenic bacteria. Therefore, precautionary measures are necessary for consumer protection, including the improvement of sanitary conditions in the processing plants and sales locations for RTE products in Korea.     

津晋地区原料奶中微生物污染程度分析与鉴定

沙门氏菌是一种重要的人畜共患肠道疾病致病菌,它引起的食物中毒已成为一类最常见且危害性较大的细菌性食物中毒。本研究对我国津晋地区原料奶中微生物污染情况进行分析与鉴定,主要包括菌落总数、大肠菌群和沙门氏菌的检测。结果显示：津晋地区原料奶来源不同,奶源质量有较大差别。菌落总数平均在104～107CFU/mL之间,存在许多超标奶;大肠菌群数差别较大,晋奶源质量很好,大肠菌群数均低于110MPN/mL,天津地区乳品厂A大肠菌群数最高为1100MPN/mL,乳品厂B受到大肠菌群的严重污染,几乎均大于或等于11000MPN/mL;沙门氏菌未检出。研究证实了津晋地区原料奶的质量和安全性不容忽视。     

Microbiological survey of retail herbs and spices from Mexican markets

In the present study, 304 samples of herbs and spices (garlic powder, cumin seeds, black pepper, oregano, and bay leaves) widely used in Mexico were analyzed for the presence of Bacillus cereus, Salmonella Typhi, Shigella dysenteriae, Escherichia coli, total and fecal coliforms, total mesophilic aerobic organisms, and fungi. Samples were nonpackaged or packaged in polyethylene bags or glass containers. High levels (10(5) to 10(7) CFU/g) of mesophilic aerobic microorganisms were found in most of the samples of garlic powder, cumin seed, and black pepper. Lower levels (<102 CFU/g) were found in oregano and bay leaves. Total and fecal coliforms counts were dependent on the type of packaging. More than 70% of the polyethylene-packaged samples had less than 10(3) CFU/g of microorganisms. Glass and nonpackaged spices showed lower levels of these microorganisms. B. cereus was present in 32 samples of which most were polyethylene packaged. The other pathogenic bacteria were not detected. Aspergillus niger was detected in 29% of the samples, Rhizopus sp. in 19%, and Penicillum sp. and Cunninghamella in 8%.