Isolation of Enterobacter sakazakii and other Enterobacteriaceae from powdered infant formula milk and related products

The presence of Enterobacter sakazakii and other Enterobacteriaceae was surveyed in 82 powdered infant formula milk (IFM) and 404 other food products. The presence of Ent. sakazakii was detected using the conventional method (growth on violet red bile glucose agar plus yellow pigment production on TSA) and a new chromogenic medium (Druggan–Forsythe–Iversen agar, DFI) which enables results to be obtained 2 days earlier than the conventional method. Ent. sakazakii was isolated from 2/82 powdered IFM, 5/49 dried infant foods, 3/72 milk powder, 2/62 cheese products and various dry food ingredients, especially herbs and spices (40/122). Ent. sakazakii was isolated from 67 samples using the DFI medium, however only 19 of the samples were positive following the conventional method. The largest difference in isolation between the two methods was with dry food ingredients.Although Enterobacteriaceae were enumerated from one powdered IFM sample (Klebsiella ozaenae, 200 cfu/g), 7/82 had detectable Enterobacteriaceae after enrichment in EE broth. Using the ISO 6579 2002 method and immuno-magnetic separation technique no Salmonella serovars were isolated from powdered IFM, dried infant foods or milk samples. Therefore hygienic production of powdered IFM and milk production as monitored by control of Salmonella and enumeration of Enterobacteriaceae did not control Ent. sakazakii.     

GAS CHROMATOGRAPHIC DETERMINATION OF VOLATILE METABOLITES FORMED BY OBESUMBACTERIUM PROTEUS AND HAFNIA SPECIES

The taxonomic relationships between 19 ‘Hafnia protea’ strains, the Obesumbacterium proteus type strain, a ‘Flavobacterium proteus’ strain, 27 H. alvei strains, an unidentified Hafnia strain, two Enterobacter cloacae strains and the type strains of Yersinia enterocolitica, ‘Y. philomiragia’, Y. pseudotuberculosis and Y. ruckeri, were determined by numerical analysis of the metabolic end products . The numerical data revealed three definite fermentation groups at a 75% similarity level. The ‘H. protea’ (14), O. proteus, ‘F. Proteus’, four Yersinia as well as six H. alvei strains in fermentation group A followed the mixed acid fermentation. Twenty one H. alvei strains, six strains received as ‘H. protea’ the Hafnia sp. and the two E. cloacae strains followed the 2,3-butanediol fermentation (fermentation groups B and C). The strains in fermentation group B formed more acid and less 2,3-butanediol than strains in fermentation group C .     

Quality and safety of halawa modified with mushroom

Halawa supplemented with 10–120 g mushroom, was evaluated for its acceptability (color, taste, texture, separate oil and overall acceptability by a ten‐member panel), protein content (as amino acid content), microbiological safety and quality. Halawa supplemented with both 10 and 20 g mushroom was equally as acceptable as the unsupplemented halawa in most sensory attributes. Results indicated that the low percentage of mushroom in halawa and control samples gave a higher panel score of all organoleptic characteristics than the high percentage of mushroom in halawa samples after 6 months storage at room temperature (25 °C). This result indicated that mushroom addition could prevent defects like oil separation and non‐coherence in halawa. It would be logical to expect a strong correlation between the sensory measure (color) of halawa and color parameters obtained by instrumental determination as well as non‐enzymatic browning (A_420nm). Techniques of regression analysis were used to predict the coefficient of correlation between the visual color score and each of the seven color parameters. The estimated values of RSQ was found to range between 0.97 (in the case of H*) to 0.98 (in the case of a*). The results showed that the aerobic plate counts increased during first the 2 months, and then decreased during the storage period for halawa fortified by different percentages of mushroom. Lipolytic microorganisms did not change during storage and remained in low numbers for halawa fortified by mushroom. Results revealed that all samples of halawa fortified by mushroom were free from clostridia, total Enterobacteriaceae count and pathogenic bacteria (Salmonella spp. and Staphylococcus aureus). It was concluded that halawa in the presence of mushroom was useful for minimizing the extent of Maillard browning reaction, maintaining color characteristics and parameters, maintaining quality and reducing water activity, and in increasing shelf‐life through inhibiting the bathogenic and reducing the spoilage bacteria. Copyright © 2006 Society of Chemical Industry     

中国市售配方粉中阪崎肠杆菌和其它肠杆菌的污染状况

目的:调查和研究我国市售配方粉中阪崎肠杆菌和其它肠杆菌的污染状况。方法:采用传统的微生物学分离和鉴定方法检测212份市售配方粉中阪崎肠杆菌和其它肠杆菌。试验采用无菌水增菌、EE肉汤选择性增菌、VRBGA平板选择性分离、TSA平板分离培养和生化鉴定等。结果:从11份配方粉中分离到阪崎肠杆菌(占检测样品总数的5.19%),从103份样品中检出肠杆菌(占检测样品总数的48.58%)。检出的肠杆菌包括:泛菌属某些种、肺炎克雷伯氏菌、阴沟肠杆菌、醋酸钙-鲍曼复合不动杆菌、阪崎肠杆菌、非脱羧勒克氏菌、伤口埃希氏菌和大肠埃希氏菌等。结论:配方粉中肠杆菌的污染可能会导致婴幼儿,特别是婴儿的严重感染。本研究结果将有助于针对我国市售配方粉的卫生预防和控制。     

Dominant Enterobacteriaceae in tempeh were primarily originated from soybean

Food Science and Biotechnology - During tempeh production, boiling was considered as heat treatment that could significantly reduce or eliminate bacterial population in soybean before fungal...     

Use of Bean Sprout Enterobacteriaceae Isolates as Biological Control Agents of Pseudomonas fluorescens

ABSTRACT: Bean sprouts were cultivated under in vitro conditions as a model system to study the mechanism of bacteria-mediated spoilage in bean sprouts. Pseudomonas fluorescens , or Erwinia spp., were inoculated onto sprouts at several stages during cultivation. Five strains of Enterobacteriaceae isolated from the native microflora of sprouts prevented Pseudomonas -mediated spoilage by co-inoculating these cultures on seeds that were soaking in water. The population of P. fluorescens in co-inoculated liquid medium culture with a strain (B1) decreased slightly. The results indicated that the Enterobacteriaceae isolates tested played an important role in preventing Pseudomonas -mediated spoilage by growing competitively with P. fluorescens .     

不同发酵条件下熏马肠中高产生物胺肠杆菌生长预测模型的研究

为了研究高产生物胺肠杆菌在不同发酵条件下的动态变化情况,将高产生物胺肠杆菌(阴沟肠杆菌和气味沙雷氏菌)接种到无污染的马肉中,并制作成熏马肠,置于20、25、30和35℃发酵条件下发酵,建立肠杆菌在熏马肠中的生长预测模型,并对模型进行验证。采用Origin 8.0统计软件拟合不同温度下肠杆菌的生长情况,研究结果表明,所选取的修正的Gompertz模型对不同发酵温度下肠杆菌在熏马肠中的生长曲线拟合效果较好,相关系数都在0.980之上。利用平方根模型反应温度与最大比生长速率和延滞时间的关系,结果呈良好的线性关系,相关系数(R2)分别为0.951 8和0.987 8,其残差的绝对值均在0.1左右浮动,表明所建立的二级模型平方根模型拟合效果较好,也说明建立的20—35℃发酵温度下熏马肠中高产生物胺肠杆菌的生长预测模型有比较好的预测效果。     

环介导等温扩增技术在肠杆菌科致病菌检测中的研究进展

环介导等温扩增（loop-mediated isothermal amplification,LAMP）技术是近年来新发展起来的一种恒温核酸扩增技术,该技术具有设备简单、检测速度快、灵敏度高、特异性强以及扩增效率高等优点,已被广泛地应用于食源性致病菌的检测研究。本文重点阐述近年来国内外学者应用LAMP技术在肠杆菌科中常见致病菌的检测研究进展。     

WORT ENTEROBACTERIA AND OTHER MICROBIAL POPULATIONS INVOLVED DURING THE FIRST MONTH OF LAMBIC FERMENTATION

Lambic is a special type of Belgian beer obtained by spontaneous fermentation. The micro-organisms occurring during the first month of lambic fermentation were counted using several selective media. During this period a mixed flora is present in which the Enterobacteriaceae predominate. They were isolated from samples of lambic of different ages originating from different breweries and identified using the minitek identification system. Much variation may occur in types of Enterobacteriaceae: Klebsiella aerogenes, Enterobacter cloacae, E. aerogenes, Escherichia coli, Citrobacter freundii, A-D group bacteria and Hafnia alvei are found during the first month of fermentation. E. cloacae is found most frequently followed by K. aerogenes. After 30 to 40 days all Enterobacteria die off because of the activities of yeasts. Lactic acid and acetic acid bacteria are found in very low numbers during the first month of fermentation; Staphylococci and Streptococci are not present.