沙门氏菌裂解性噬菌体的分离鉴定及其生物学特性

从家禽屠宰场污水中,以肠炎沙门氏菌ATCC13076和禽沙门氏菌CVCC2184为宿主菌,分离到两株裂解性沙门氏菌噬菌体,分别命名为vB_SenM-PA13076（简称PA13076）和vB_SenM-PC2184（简称PC2184）。同时对这两株噬菌体进行了噬菌斑、噬菌谱系（含耐药菌）、形态学（透射电镜）、遗传物质、酸碱及热稳定性、最佳感染复数、一步生长曲线等生物学特性研究。结果表明：两株噬菌体的裂解空斑均透亮清晰;除对本身宿主菌产生强裂解作用,还裂解其他沙门氏菌,为宽噬菌谱,其中PA13076能强裂解一株耐氨苄青霉素ATCC13076转化菌株（A+13076）,PC2184则能裂解另一株耐氨苄青霉素CVCC2184转化菌株（A+2184）;电镜观察这两株噬菌体均为肌尾病毒科;遗传物质为dsDNA;pH值和温度耐受能力较好;PA13076、PC2184最佳感染复数分别为0.01、10,潜伏期分别为20、30 min,爆发期分别为70、60 min,平均爆发量分别为21、23。     

一株耐甲氧西林金黄色葡萄球菌噬菌体qdsa002的分离鉴定及其生理学性质研究

为探究耐甲氧西林金黄色葡萄球菌的生物防治方法,从青岛市团岛污水处理厂采集到的污水中分离得到了一株噬菌体qdsa002。借助噬菌斑形态、酶切、电镜等技术对其进行了分类鉴定。研究了其最佳感染复数、一步生长曲线、p H稳定性和热稳定性等生理学特征。结果表明,qdsa002核酸属于线型双链DNA,具有正多面体的头部及较长的尾部,qdsa002头部直径约47 nm,尾长约120 nm,属肌尾噬菌体科。生理学特征研究结果表明,qdsa002在双层平板上能形成清晰透亮的噬菌斑。最佳感染复数为0.001,潜伏期40 min,爆发期180 min。在p H为5~9范围内能够保持良好的生理活性。在温度不高于50℃条件下裂解性能良好。该噬菌体可用于防治MRSA感染的生物制剂。     

李斯特菌噬菌体的分离鉴定及其裂解特性

以单核细胞增生性李斯特菌(Lm)为宿主菌,从畜禽养殖区污水中分离(Lm)特异的噬菌体,分析其生物学特性、裂解特性及其在食品中的灭菌效果。用双层平板法从污水样中分离Lm噬菌体,PEG/NaCl法沉淀纯化噬菌体,负染色后电镜观察。分析噬菌体对宿主菌的裂解特性及其对温度和pH值的敏感性,同时对该噬菌体进行宿主谱系分析。将噬菌体运用于即食性食品中,分析其潜在的灭菌效果。结果表明:分离的噬菌体为裂解性噬菌体,属长尾噬菌体科,命名为LipG2-5。体外能够高效裂解宿主菌,对温度及pH值亦有良好的耐受性。基因组酶切分析表明,LipG2-5为双链DNA噬菌体。噬菌体谱系分析表明,该噬菌体为1株宽宿谱噬菌体,在固态及液态即食性食品中能够高效杀灭Lm。     

假单胞菌噬菌体PSJ-1的生物学特性及在冷却羊肉中的初步应用

以产碱假单胞菌为宿主菌,使用点滴法和双层平板法筛选出一株裂解性噬菌体,命名为PSJ-1,研究其生物学特性及在冷却羊肉中的抑菌效果。结果表明,噬菌体PSJ-1噬菌斑透明,直径为1～2 mm;透射电镜观察显示,其具有直径约86 nm的二十面体头部和长约176 nm的尾部,属于长尾噬菌体科(Siphoviridae)。噬菌体PSJ-1的最佳感染复数是0.1,在最佳感染复数下的潜伏期约为20 min,裂解期约为30 min,裂解量为32 PFU/cell。PSJ-1在30～70 ℃、pH2～11的条件下都可以存活,抑菌实验结果表明,PSJ-1可以显著降低冷却羊肉中产碱假单胞菌的数量。     

噬菌体vB_SauM_RS对乳源金黄色葡萄球菌生物被膜的清除作用

目的:以金黄色葡萄球菌为宿主菌,分离裂解性噬菌体vB_SauM_RS,测定其生物学特性,并探究其在两种牛奶中的抑菌效果及对生物被膜的清除作用.方法:将噬菌体与金黄色葡萄球菌以1∶100的比例(菌体数量比)分别接种于脱脂牛奶和全脂牛奶中,分别在4℃和25 ℃环境下处理,测定不同时间脱脂牛奶和全脂牛奶中细菌浓度和噬菌体效价...     

食源性大肠杆菌噬菌体的分离及其特性分析

目的从污水样品中分离致病性大肠杆菌的烈性噬菌体,分析其生物学特性,为食品中致病性大肠杆菌的控制提供参考。方法以标准菌株Escherichia coli EPEC(CICC10664)为宿主菌,采用双层平板法,从扬州市各地污水中分离纯化噬菌体,通过透射电镜观察其形态、测定最佳感染复数、一步生长曲线、裂解镨及其对宿主菌生物被膜的影响。结果分离到一株肠致病性大肠杆菌烈性噬菌体,命名为Ec.P01,电镜观察其为肌尾噬菌体,直径约为80 nm,最佳感染复数为0.01,一步生长曲线显示其噬菌体Ec.P 01的平均裂解量为48 PFU/m L,潜伏期约为10 min,裂解期约为90 min,热稳定性较好,对宿主菌生物被膜的形成有明显的抑制作用。结论本研究分离到一株肠致病性大肠杆菌烈性噬菌体,为治疗大肠杆菌感染疾病和治理食品及其环境污染提供新的思路与方法。     

霍乱弧菌噬菌体在消除海产品中相关弧菌的潜在应用研究

噬菌体具有裂解病菌的作用,可用作生物净化因子.本实验以霍乱弧菌为宿主菌,采用双层平板法从鲍鱼养殖环境中分离到5株霍乱弧茵噬菌体.以23株弧菌为宿主菌,本文研究了霍乱弧菌噬菌体对海产品中常见弧茵的裂解消除能力,同时针对宽裂解谱噬菌体进行包括热失活、pH稳定性、紫外照射、不同镁离子浓度、不同柠檬酸钠浓度等理化因素对其裂解能力的影响,以探索其裂解消除弧茵的最优条件.实验结果表明噬菌体在消除霍乱弧菌方面有潜在的应用价值,紫外照射、柠檬酸钠对噬菌体裂解有不同程度的抑制作用,温度和pH值对噬茵体裂解也有不同程度的影响,而适度的镁离子则有促进作用.     

一株空肠弯曲菌噬菌体vB＿Cj＿QDYZ的生物学特性和全基因组分析

空肠弯曲菌是一种重要的人畜共患病原菌，能引起人类细菌性腹痛腹泻。随着空肠弯曲菌耐药性日益严重，亟需筛选能高效裂解空肠弯曲菌的噬菌体，为应用噬菌体防治空肠弯曲菌污染提供理论基础。该研究分离一株能高效裂解空肠弯曲菌的噬菌体，将其命名为vB＿Cj＿QDYZ。电镜结果显示该噬菌体有一个正二十面体的头部(直径约100.81 nm)和一条可伸缩的尾部(长度约65.90 nm)。噬菌体vB＿Cj＿QDYZ的温度耐受范围为30～60℃,在pH值为3～12时效价较稳定。噬菌体的最佳感染复数为0.01,一步生长曲线表明，噬菌体的潜伏期是60 min,裂解期是150 min,爆发量是45 PFU/cell。噬菌体的基因组全长为130 627 bp, G+C含量为26%,共有165个开放阅读框，3个tRNA。基因组中不含毒力基因、抗生素耐药基因及过敏原基因。比较基因组学表明噬菌体vB＿Cj＿QDYZ可能是来自Eucampyvirinae亚科，Fletchervirus属的新成员。噬菌体vB＿Cj＿QDYZ是一株裂解能力较强、热稳定性和pH稳定性良好的空肠弯曲菌噬菌体，具有开发为新型空肠弯曲菌抗菌剂的潜力。     

1株副溶血性弧菌裂解性噬菌体VpJYP2的生物学特性及应用

对1株副溶血性弧菌裂解性噬菌体VpJYP2进行生物学特性分析,探讨VpJYP2对生三文鱼片中副溶血性弧菌的杀菌效果。结果显示,噬菌体VpJYP2的噬菌斑透明,直径为1～2 mm,外有晕圈;透射电镜观察显示,其头部呈二十面体立体结构,直径约64 nm,尾部长约70 nm,尾鞘带宽约20 nm,属于肌尾病毒科(Myoviridae);VpJYP2基因组全长25 363 bp,含有45个开放阅读框,推定为已知功能的有13个;VpJYP2在40～50℃稳定,在pH 4～11稳定,最佳感染复数为0.01,感染宿主菌的潜伏期约为5 min,裂解期约为55 min,裂解量约为45。VpJYP2能显著降低生三文鱼片中副溶血性弧菌的含量。结果表明,VpJYP2具有作为副溶血性弧菌生物杀菌剂的应用潜力。     

1 株裂解性短尾沙门氏菌噬菌体T139的生物学特性及其对牛奶和牛肉的抑菌作用

采用双层平板的方法以鼠伤寒沙门氏菌（ATCC 13311）为宿主菌,从污水中分离得到1 株裂解性噬菌体,命名为T139,研究其生物学特性及其在牛奶和牛肉样品中的抑菌作用。结果表明：噬菌体T139的噬菌斑透亮清晰;能裂解宿主菌及其他沙门氏菌,为宽宿主谱;电镜观察噬菌体T139属于短尾噬菌体科,头部直径为（43±1）nm,尾部长（11±0.6）nm;最佳感染复数（multiplicity of infection,MOI）为0.001;最佳吸附速率为66%;一步生长曲线结果显示潜伏期为5?min,爆发期为60?min,平均裂解量为54.54?PFU/cell;在30～50?℃和pH?4～12条件下稳定且对体外培养的鼠伤寒沙门氏菌有良好的裂解效果。噬菌体T139对牛奶中鼠伤寒沙门氏菌的抑菌效果为：在4?℃无显著效果,在25?℃条件下MOI=10和MOI=100时抑菌效果极其显著,宿主菌数量分别下降4.32（lg（CFU/mL））和4.27（lg（CFU/mL））;噬菌体T139对牛肉中鼠伤寒沙门氏菌的抑菌效果为：在4?℃条件下,MOI=10时无显著效果,在MOI=100时宿主菌数量下降0.66（lg（CFU/mL））,在25?℃条件下MOI=10和MOI=100时宿主菌数量分别下降了0.77（lg（CFU/mL））和1.16（lg（CFU/mL））,表明噬菌体T139对牛奶和牛肉中鼠伤寒沙门氏菌有良好抑制作用。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Detection of adulteration of locust bean gum with guar gum by capillary electrophoresis and polarized light microscopy

Capillary electrophoresis (CE) and polarized light microscopy (PLM) were utilized in the detection of the adulteration of locust bean gum with guar gum. For CE analyses, standards of locust bean and guar gums were extracted with 30% CH₃CN, removing the residual proteins from the gum matrix. A 8.75 mM NaH₂PO₄-20.6 mM Na₂B₄O₇ buffer, pH 9, was used to separate these proteins and to identify marker proteins that were present in the guar gum. These markers did not co-migrate with components in the extracts of mechanically processed locust bean gum, and are used as indicators of adulteration. Using PLM with toluidine blue and iodine staining techniques, unadulterated locust bean gum samples were distinguished from mixed samples through the differential staining of components in locust bean versus guar and tara gums. These experiments in the use of CE and PLM provide orthogonal and complementary methods for the verification of 'true' positives and the elimination of 'false' positives.