A mixed-species microarray for identification of food spoilage bacilli

Failure of food preservation is frequently caused by thermostable spores of members of the Bacillaceae family, which show a wide spectrum of resistance to cleaning and preservation treatments. We constructed and validated a mixed-species genotyping array for 6 Bacillus species, including Bacillus subtilis, Bacillus licheniformis, Bacillus pumilus, Bacillus sporothermodurans, Bacillus cereus and Bacillus coagulans, and 4 Geobacillus species, including Geobacillus stearothermophilus, Geobacillus thermocatenulatus, Geobacillus toebii and Geobacillus sp., in order to track food spoilage isolates from ingredient to product. The discriminating power of the array was evaluated with sets of 42 reference and 20 test strains. Bacterial isolates contain a within-species-conserved core genome comprising 68-88% of the entire genome and a non-conserved accessory genome comprising 7-22%. The majority of the core genome markers do not hybridise between species, thus they allow for efficient discrimination at the species level. The accessory genome array markers provide high-resolution discrimination at the level of individual isolates from a single species. In conclusion, the reported mixed-species microarray contains discriminating markers that allow rapid and cost-effective typing of Bacillus food spoilage bacteria in a wide variety of food products.     

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。     

2011~2015年保山市食品中食源性致病菌监测结果分析

目的 了解保山市食品中食源性致病菌污染状况, 为监督管理提供科学依据。方法 2011~2015年按照《食品安全风险监测方案》样品采样要求抽样9类, 1404份食品样品。根据《食源性致病菌检验标准操作程序》方法对抽取的样品进行蜡样芽孢杆菌、金黄色葡萄球菌、沙门氏菌等12种致病菌监测。结果 2011~2015年间检测样品中, 阳性样品83份, 检出6种食源性致病菌85株, 致病菌污染率为5.91%, 其中蜡样芽孢杆菌检出率最高为19.63%。不同年份食源性致病菌污染率差异有统计学意义(P<0.001)。9类食品中婴幼儿食品及餐饮食品致病菌污染率最高, 分别为17.27%、14.81%; 散装食品致病菌污染率7.92%, 高于预包装食品3.28%(P<0.001); 第3季度的致病菌污染率为10.2%, 显著高于其他季度(P<0.008); 餐饮服务环节6种致病菌总污染率高于流通环节及生产加工环节。结论 保山市食品中存在食源性致病菌的污染, 食品安全监管部门应加强食品安全监督管理, 重点对散装食品进行监测监督, 在污染率高的第3季度及餐饮服务环节加强监管。     

四种不同接触表面蜡样芽孢杆菌菌膜形成的影响

为了解食源性致病菌蜡样芽孢杆菌在食品加工环境中菌膜形成能力,以玻璃、不锈钢、聚氯乙烯、聚丙烯为接触面,采用超声波平板菌落计数法测定不同环境因素(温度、pH、氯化钠、葡萄糖、苯甲酸钠及山梨酸钾)、不同材料表面蜡样芽孢杆菌(B.cereus)菌膜形成的变化趋势。结果表明:四种材质表面形成B.cereus菌膜能力的大小顺序为:玻璃 > 不锈钢 > 聚氯乙烯 > 聚丙烯。其中,30 ℃,pH7.0时菌膜形成量最大,添加低浓度葡萄糖(4.0%)或氯化钠(0.5%)对B.cereus菌膜形成有显著促进作用(p<0.05),添加0.15%苯甲酸钠、山梨酸钾的菌膜形成量显著高于添加0.10%的菌膜形成量(p<0.05)。本研究为蜡样芽孢杆菌风险评估提供基础数据,为食品工业蜡样芽孢杆菌菌膜的预防和控制奠定基础,为改进蜡样芽孢杆菌的清洗控制措施提供参考。     

2016年松原市食品中食源性致病菌的风险监测

［］目的 了解松原市市售食品的食源性致病菌污染状况。方法 2016年采集全市五个县、市(区)12类食品,依据吉林省2016年食源性致病菌监测工作手册,检测沙门氏菌、金黄色葡萄球菌、副溶血性弧菌、单增李斯特氏菌、阪崎肠杆菌、蜡样芽孢杆菌、致泻性大肠杆菌等7种致病菌。结果 在采集的12类共205份食品中,检出致病菌22株,总检出率为10.7%。在8种致病菌中,阪崎肠杆菌检出率最高30%,其次是蜡样芽孢杆菌11.1%。在12类食品中,婴幼儿谷类辅助食品污染率最高45%,其次为学生餐26.7%。动物性淡水产品、即食非发酵豆制品、鲜榨果蔬汁等食品均存在不同程度的污染。结论 松原市食品中存在不同程度的食源性致病菌污染,婴幼儿食品存在受致病菌污染的风险,其食品安全应得到重视和加强监管。     

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。     

生鲜食品中蜡样芽孢杆菌毒力基因及耐药性研究

目的:研究生鲜食品中蜡样芽孢杆菌的毒力基因及耐药性。方法:在成都市周边农贸市场和路边小摊采集各种生鲜食品共100份,采用MYP选择性培养基初步分离蜡样芽孢杆菌菌株,采用16S rRNA序列比对分析鉴定得到蜡样芽孢杆菌分离菌株,采用PCR检测分离鉴定菌株中蜡样芽孢杆菌13个毒力基因的携带情况,进一步采用纸片扩散法检测菌株对18种抗生素的耐药性。结果:从100份生鲜食品样本中,检出蜡样芽孢杆菌24株,检出率为24%,其中,路边小摊的检出率(70%)高于农贸市场(18.9%)。呕吐型基因ces和cer的检出率较低,仅在1株中发现;腹泻型基因nheC有24株检出;cytK有13株检出;bceT有12株检出;hblA有11株检出;nheB有10株检出;hblC、hblD、nheA各有9株检出;hly-Ⅱ有7株检出;hblB、entFM检出率为0;蜡样芽孢杆菌的4个看家基因rpoB、gyrB、groEL、vrrA在24株分离菌株中检出率为100%。同时发现,生鲜食品来源的蜡样芽孢杆菌分离菌株对杆菌肽B、磺胺甲亚唑、苯唑西林、青霉素表现出较高耐药性,耐药率大于96%;而对阿米卡星、氯霉素、庆大霉素、亚胺培南耐药率小于7%。结论:本研究通过分离鉴定生鲜食品源蜡样芽孢杆菌,研究其毒力基因携带及耐药性,为进一步评价生鲜食品中蜡样芽孢杆菌的安全风险提供参考数据。     

In vitro probiotic evaluation of potential antioxidant lactic acid bacteria isolated from idli batter fermented with Piper betle leaves

Lactic acid bacteria isolated from food sources can be introduced as probiotics because of their health‐promoting and nonpathogenic characteristics. Eight lactic acid bacteria from idli batter fermented with Piper betle leaves were selected to screen the antioxidant potential and biofilm‐forming ability. Five isolates exhibited good antioxidant potential and biofilm formation and showed antagonistic activity against the pathogenic biofilm‐forming Staphylococcus aureus. Further, in vitro probiotic properties of five isolates exhibited excellent acid tolerance, bile tolerance, simulated gastrointestinal juice tolerance, auto‐aggregation and co‐aggregation and hydrophobicity and showed resistance to antibiotics such as ciprofloxacin, nalidixic acid, norfloxacin and colistin. Isolates also showed positive bile salt hydrolase activity, cholesterol assimilation, β‐galactosidase production and mucin binding ability. The isolate KJBB10 exhibited good adhesion and pathogen exclusion percentage with human colon cancer cells (HCT‐15 and HT‐29). Hence, the isolates KJBB10, KJBB56 and KJBC06 can be used as beneficial probiotic starter cultures for the formulation of functional foods.     

Isolation and applied potential of lactic acid bacteria from Chinese traditional fermented food in specific ecological localities

The isolation and screening of lactic acid bacteria (LAB) from natural sources have been one of the powerful means to obtain strains for the food industry. A total of 275 indigenous isolates were obtained from 43 samples of traditional fermented foods in specific ecological niches throughout the northwestern China, and among which 13 strains of LAB were selected for their potential in food preservation and production. Among the 13 isolates, Lactobacillus (10) was dominant over Lactococcus (3). The distribution of the isolates was as follows: Lactobacillus paracasei ssp. paracasei (J23, M10, M20, M22), Lactobacillus rhamnosus (J20, M18), Lactococcus lactis ssp. lactis (X20, Q7), Lactobacillus casei (Q1, Q12), Lactobacillus plantarum (J11), Lactococcus lactis ssp. cremoris (X8), Lactobacillus delbrueckii ssp. bulgaricus (Q5). All 13 isolates produced bacteriocin with a broad inhibitory spectrum against selected Gram-positive as well as Gram-negative pathogenic and spoilage species. Biochemical analysis revealed that they possessed high acidification and coagulation activity. Several strains possessed the high activity of 2 or 3 technological characteristics, related to novel starters and food preservatives.     

Effect of food residues on efficiency of surfactant disinfectants against food related pathogens adhered on polystyrene and ceramic surfaces

The adhesion of pathogenic bacteria on food contact surfaces increases the risk of cross-contamination in the food industry. However, food-borne disease introduced by the production process can be mitigated by surfactant use. This study investigates the effect of food residues (milk, beef gravy and tuna gravy) on the bactericidal efficiency of benzalkonium chloride (BAC) and alkyldiaminoethylglycine hydrochloride (AGH). The test was conducted on pathogenic bacteria (Escherichia coli O26, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus cereus, and B. cereus spores) dried and adhered to the surfaces of polystyrene and ceramic dishes at room temperature for 1.5 h. The protein and lipid rich food residues protected the bacterial cells from dehydration and from the adverse effects of disinfectants, although bacterial numbers were decreased after drying and the surfaces were clearly sterilized after disinfectant treatment at typical concentrations (0.5 mg/ml–2.0 mg/ml) for 10 min. Following general and proper washing processes, the bactericidal effect of the disinfectants became clearly visible. These results indicate that applying a proper washing process prior to disinfectant treatment can prevent cross-contamination.     

Differentiation and characterization by molecular techniques of Bacillus cereus group isolates from poto poto and dégué, two traditional cereal-based fermented foods of Burkina Faso and Republic of Congo

Poto poto (a maize sourdough) and dégué (a pearl millet-based food) are two traditional African fermented foods. The molecular biology of toxigenic and pathogenic bacteria found in those foods is largely unknown. The purpose of this study was to study the phylogenetic relatedness and toxigenic potential of 26 Bacillus cereus group isolates from these traditional fermented foods. The relatedness of the isolates was evaluated with repetitive element sequence-based PCR (REP-PCR) and 16S rDNA sequencing analysis. A multiplex real-time PCR assay targeting the lef and capC genes of B. anthracis pXO1 and pXO2 plasmids and the sspE chromosomal gene of B. cereus and B. anthracis also was carried out. Melting curve analysis of the sspE amplification product was used to differentiate B. cereus from B. anthracis, and the presence of the B. cereus enterotoxin genes was determined with PCR amplification. Isolates had 15 different REP-PCR profiles, according to which they could be clustered into four groups. 16S rDNA sequencing analysis identified 23 isolates as B. cereus or B. anthracis and three isolates as B. cereus or Bacillus sp. Multiplex real-time PCR amplification indicated the absence of the lef and capC genes of B. anthracis pXO 1 and pXO2 plasmids, and melting curve analysis revealed amplification of the 71-bp sspE product typical of B. cereus in all isolates instead of the 188-bp amplicon of B. anthracis, confirming the identity of these isolates as B. cereus. Four isolates had amylolytic activity. All isolates had lecithinase activity and beta-hemolytic activity. Enterotoxin production was detected in two isolates. The emetic toxin gene was not detected in any isolate. The nheB toxin gene was detected in 19 isolates by PCR amplification; one of these isolates also contained the hblD (L1) gene. The cytotoxin K cytK-1 gene was not detected, but the cytK-2 gene was clearly detected in six isolates.     

抗食源性病原菌细菌素的筛选及特性研究

目的 筛选一种抗食源性病原菌的细菌素,并对其稳定性进行研究.方法 以食源性病原菌Bacillus cereus ATCC 14579、Listeria monocytogenes LM201、Listeria monocytogenes LM605为指示菌,采用琼脂扩散法筛选细菌素产生菌,通过离子交换树脂法和高效液相色...     

2013年滁州市食源性致病菌监测分析

目的了解和掌握滁州市食品中食源性致病菌污染状况,为开展食品安全风险评估和确定高危食品种类、分布提供科学依据。方法按照《2013年国家食品污染和有害因素风险工作手册》中的标准操作程序,对市售10类食品进行金黄色葡萄球菌、沙门氏菌、志贺氏菌、单增李斯特菌、蜡样芽胞杆菌、阪崎肠杆菌、致泻大肠埃希氏菌、铜绿假单胞菌共8种食源性致病菌的检测。结果共抽检169份样品,检出致病菌17株,总检出率10.06%。其中蜡样芽胞杆菌12株、铜绿假单胞菌3株、致泻性大肠埃希氏菌2株。结论滁州地区市售食品存在不同程度的食源性致病菌污染,有一定的食品安全风险。其中婴幼儿食品、乳制品和桶装水等污染较为严重,主要污染菌为蜡样芽胞杆菌、铜绿假单胞和致泻性大肠埃希氏菌。     

Incidence,Antibiotic Susceptibility,and Toxin Profiles of Bacillus cereus sensu lato Isolated from Korean Fermented Soybean Products

Korean fermented soybean products, such as doenjang, kochujang, ssamjang, and cho‐kochujang, can harbor foodborne pathogens such as Bacillus cereus sensu lato (B. cereus sensu lato). The aim of this study was to characterize the toxin gene profiles, biochemical characteristics, and antibiotic resistance patterns of B. cereus sensu lato strains isolated from Korean fermented soybean products. Eighty‐eight samples of Korean fermented soybean products purchased from retails in Seoul were tested. Thirteen of 26 doenjang samples, 13 of 23 kochujang samples, 16 of 30 ssamjang samples, and 5 of 9 cho‐kochujang samples were positive for B. cereus sensu lato strains. The contamination level of all positive samples did not exceed 4 log CFU/g of food (maximum levels of Korea Food Code). Eighty‐seven B. cereus sensu lato strains were isolated from 47 positive samples, and all isolates carried at least one enterotoxin gene. The detection rates of hblCDA, nheABC, cytK, and entFM enterotoxin genes among all isolates were 34.5%, 98.9%, 57.5%, and 100%, respectively. Fifteen strains (17.2%) harbored the emetic toxin gene. Most strains tested positive for salicin fermentation (62.1%), starch hydrolysis (66.7%), hemolysis (98.9%), motility test (100%), and lecithinase production (96.6%). The B. cereus sensu lato strains were highly resistant to β‐lactam antibiotics such as ampicillin, penicillin, cefepime, imipenem, and oxacillin. Although B. cereus sensu lato levels in Korean fermented soybean products did not exceed the maximum levels permitted in South Korea (<10⁴ CFU/g), these results indicate that the bacterial isolates have the potential to cause diarrheal or emetic gastrointestinal diseases.     

Antimicrobial activity of a meat-borne Bacillussubtilis strain against food pathogens

The aim of this study was to test the antibacterial activity of Bacillus subtilis TR50 isolated from a traditional cured sausage against ten food-borne pathogenic bacteria. Most of the pathogens were sensitive to cell-free concentrated supernatant from TR50. The inhibitory activity was retained at pH values between 4 and 8, up to 80 °C for 30 min and after treatment with pepsin and trypsin, whereas it disappeared after chymotrypsin hydrolysis; lipase treatment abolished inhibitory activity only against one target strain. The ammonium sulphate precipitation of TR50 concentrated cell-free culture retained the most residual antibacterial activity unlike the ethyl acetate and acid fractions. All these results suggest that the antimicrobial compound(s) produced by TR50 could be of proteinaceous nature and require a lipid moiety for activity against the pathogens tested. This is the first report on the antimicrobial activity against food-borne pathogens of a B. subtilis strain occurring in a traditional sausage potentially useful for food safety improvement.     

2010~2015年吉林市食品食源性致病菌的风险监测结果分析

目的 分析吉林市市售食品中食源性致病菌的污染情况,确定高危食品的种类和分布,预防和控制食源性疾病的发生。方法 2010～2015年采集吉林市市售样品21类1212份,按照《全国食源性致病菌监测工作手册》的要求分离和鉴定10种食源性致病菌。结果 检出致病菌株121株,总检出率为9.98%。致病菌检出率前3位食品类别分别是速冻米面制品(26/96,27.08%);乳与乳制品、婴幼儿配斱食品(23/101,22.77%);肉及肉制品(40/178, 22.47%)。检出致病菌前3位是蜡样芽胞杆菌(43/206, 20.87%)、副溶血性弧菌(6/77, 7.79%)、单核细胞增生李斯特菌(42/643, 6.53%)。2010～2015年每年食源性致病菌检出率分别为8.56%、2.99%、6.55%、2.86%、1.83%、3.49%。结论 吉林市市售食品的现状不容乐观,食源性致病菌污染严重,致病菌检出率进高于同期本省及国内其他省市。建议长期注意其引起的食源性疾病风险,加强市售食品的监测和食品经营部门的管理,防止食源性疾病的发生。     

2014~2016年丽江市食品中食源性致病菌监测结果分析

目的 了解丽江市食品中食源性致病菌的污染状况, 为开展丽江市食品安全评估和确定高风险食品种类和分布提供科学依据。方法 2014~2016年采集丽江市售食品344份, 对沙门氏菌、单增李斯特菌、金黄色葡萄球菌、副溶血性弧菌、空肠弯曲菌、蜡样芽孢杆菌6种食源性致病菌进行监测分析。结果 344份食品样品检出食源性致病菌51株, 总检出率为14.82%。3年食源性致病菌检出率分别为21.00%、15.13%和9.60%, 不同年份检出率差异有统计学意义。检出的4种食源性致病菌, 其中以蜡样芽孢杆菌和金黄色葡萄球菌检出率最高, 分别为8.14%和3.49%; 空肠弯曲菌、副溶血性弧菌未检出。米米制品、学生餐(盒饭)和生肉类污染严重, 检出率分别为23.53%、18.18%和16.92%。结论 丽江市辖区市售食品中存在不同程度的食源性致病菌污染, 食品安全监管部门应加强食品安全监督管理。     

Diverse Profiles of N‐acyl Homoserine l‐Lactones,Biofilm, Virulence Genes and Integrons in Food‐Borne Aeromonas Isolates

Aeromonas are regarded as opportunistic as well as primary pathogens of humans and fish, and are associated with gastroenteritis and septicemia in humans. Production of N‐acyl‐homoserine lactone (AHL) signal molecules and biofilm was determined in 22 Aeromonas isolates, from different food products in India, using thin‐layer chromatography (TLC) analysis and microtiter‐plate assay, respectively. Overall, highly heterogeneous patterns of AHL production were observed, with the production of N‐butanoyl homoserine lactone (C4‐HSL) and N‐hexanoyl homoserine lactone (C6‐HSL) by the majority (81.8%) of Aeromonas food isolates. Moreover, putative N‐pentanoyl homoserine lactone (C5‐HSL), N‐heptanoyl homoserine lactone (C7‐HSL), and N‐octanoyl homoserine lactone (C8‐HSL) were produced by 72.7%, 27.3%, and 9.1% of isolates, respectively. This is the 1st report of production of C7‐HSL by Aeromonas species. Aeromonas food isolates were highly variable in their biofilm forming abilities with majority of them as weak biofilm producers in 2 different media, TSB and M9 minimal medium supplemented with 0.4% glucose. The genes encoding for putative virulence factors, glycerophospholipid cholesterol acyltransferase (gcat), heat‐labile cytotonic enterotoxin (alt), heat‐stable cytotonic enterotoxin (ast), serine protease (ser), polar flagella (fla), and lateral flagella (lafA) were present in 95.5%, 59.1%, 22.7%, 81.8%, 77.3%, and 22.7% of the strains, respectively. Class 1 integrons (100 to 3000 bp) were found in 68.2% of food isolates; whereas, 50% isolates contained class 2 integrons (150 to 1600 bp). This study provides a baseline data on the diversity of AHLs, biofilm forming ability and presence of virulence genes and integrons in Aeromonas food isolates from India.     

北京市密云区餐饮食品中食源性致病菌监测结果分析

摘要: 目的 分析北京市密云区餐饮食品中食源性致病菌污染状况。 方法 按照《国家食品污染和有害因素风险监测工作手册》要求,在密云区的餐饮单位和网络外卖配送平台随机抽取餐饮食品,进行沙门氏菌、金黄色葡萄球菌、单增李斯特氏菌、蜡样芽胞杆菌、副溶血性弧菌、创伤弧菌、溶藻弧菌、河弧菌和致泻大肠埃希氏菌检测。结果 2018～2020年共采集餐饮食品6类210件,总检出率为8.10%（17件）。检出致病菌3种,其中单增李斯特氏菌检出率最高（7.27%）,其次是蜡样芽孢杆菌（4.55%）、致泻大肠埃希氏菌（0.83%）。在冷荤凉菜、熟制米面制品、沙拉和焙烤食品中食源性致病菌检出率分别是14.86%、11.76%、8.33%和5.0%。外卖配送平台餐饮食品检出率（11.65%）高于实体店购买餐饮食品（4.67%）。结论 密云区餐饮食品存在不同程度的致病菌污染,应对网络外卖配送平台和餐饮单位加强监管和健康宣教,采取针对性的措施,预防食源性疾病和食物中毒的发生。     

Differential inactivation of food poisoning bacteria and Lactobacillus sp. by mandelic acid

Microbicides are used to eliminate pathogenic bacteria, but they can also eliminate beneficial and normal bacteria. This study provides antimicrobial information of mandelic acid (MA) prior to its widespread use. The MA susceptibilities of Lactobacillus sp. and pathogens were determined by dilution method based on NCCLS protocol. The concentration of MA at 5.0 mg/mL inhibited 90% of the Lactobacillus sp., whereas a 1.25 mg/mL concentration inhibited the following pathogenic bacteria strains: Listeria monocytogenes KCTC3710, Yersinia enterocolitica ATCC23715, and Shigella sonnei ATCC9290. The minimal inhibitory concentration (MIC) for Escherichia coli O157:H7, Salmonella enteritidis KCTC12400, Salmonella gallinarum ATCC9148, Salmonella typhimurium ATCC29631, and Staphylococcus aureus KCCM40881 was at 2.5 mg/mL. These pathogens were also inhibited by addition of 1.0 M NaCl in 2 mg/mL MA solution (pH 5.0), while lactobacilli were not affected. These results indicate that MA can prevent disease and food poisoning when applied as a disinfectant in food industry, hospitals, and public places.