高富硒酵母菌诱变选育研究

对36株不同来源的酵母菌进行了硒耐受性分析和比较,获得1株硒耐受性和富硒能力较强的热带假丝酵母菌(Candida tropicalis)菌株1254。以该菌株为出发菌株,进行了亚硝基胍诱变和亚硒酸钠抗性筛选、紫外线诱变和乙硫氨酸抗性筛选等两轮突变和筛选,获得突变菌株1254-6-1,其生物量、总硒含量、有机硒的含量及转化率达到7.60 g/l、5 626.00μg/g、4 879.99μg/g、86.74%,分别为原始出发菌株的1.85倍、7.90倍、9.35倍、1.18倍;各种氨基酸的含量均高于出发菌株,其中蛋氨酸和胱氨酸的含量分别是出发株的135%和194.10%。     

高生物量富硒酵母菌的选育

以酿酒酵母PT为出发菌株,采用梯度浓度筛选的方法对其进行驯化,得到1株生物量较高和对亚硒酸钠抗性较高的菌株GB-1。对其进行紫外诱变处理,当致死率达91.85%时,获得多株突变株。通过多次平板初筛和摇瓶复筛,得到1株高生物量富硒酵母UV-PT。采用响应面法对富硒酵母UV-PT发酵条件进行了优化。借助于SAS软件,首先利用Plackett-Burman试验设计筛选出影响富硒的3个主要因素,即转速、温度、初始pH值。在此基础上,再利用Box-Behnken试验设计及响应面分析法对发酵条件进行优化,确定最佳发酵条件:转速为203r/min,发酵温度为30.3℃,初始pH值为4.52。结果表明,优化后富硒酵母的生物量和含硒量分别为10.62g/L、1003.26μg/g,硒总含量为10654.62μg/L,为出发菌株的1.62倍。     

富硒酵母的选育及其发酵条件的优化试验

通过对一株耐硒酵母进行UV和60Co逐级诱变,获得一株产量高的突变株Y7,发酵液的硒总含量达19mg/L,是出发菌株的1.58倍,经多次传代试验,证明其稳定性良好。通过单因素、L16(37)正交试验对其发酵培养基和培养条件进行优化,试验表明富硒酵母发酵培养基的最佳配方是:蔗糖6%,牛肉膏1%,蛋白胨1%,K2HPO4 0.15%,亚硒酸钠35μg/L;最佳培养条件:初始pH为4.0,温度32℃,装液量60mL/250mL摇瓶,转速200r/min,10%(v/v)接种量,培养48h。富硒酵母的硒总含量达23mg/L以上,是出发菌株的1.92倍。     

高生物量富硒酵母菌的选育

以酿酒酵母PT为出发菌株,采用梯度浓度筛选的方法对其进行驯化,得到1株生物量较高和对亚硒酸钠抗性较高的菌株GB-1.对其进行紫外诱变处理,当致死率达91.85%时,获得多株突变株.通过多次平板初筛和摇瓶复筛,得到1株高生物量富硒酵母UV-PT.采用响应面法对富硒酵母UV-PT发酵条件进行了优化.借助于SAS软件,首先利用Plaekett-Burman试验设计筛选出影响富硒的3个主要因素,即转速、温度、初始pH值.在此基础上,再利用Box-Behnken试验设计及响应面分析法对发酵条件进行优化,确定最佳发酵条件:转速为203r/min,发酵温度为30.3℃,初始PH值为4.52.结果表明,优化后富硒酵母的生物量和含硒量分别为10.62g/L、1003.26ug/g,硒总含量为10654.62ug/L,为出发菌株的1.62倍.     

高富硒酵母菌株的筛选及其富硒特性分析

以酿酒酵母（Saccharomyces cerevisiae）为出发菌株,NaN3为诱变剂、H2O2为选择压力进行菌株诱变筛选,以总硒及有机硒的含量与产率、硒磷酸合成酶（SPS）活性和蛋白硒含量为评价指标进行菌株富硒特性研究。结果表明,经10 mol/L NaN3处理40 min和2.50%H2O2筛分,从出发菌株中得到两株富硒水平高、富硒能力稳定的菌株HXS-01和HXS-02,经48 h摇瓶富硒培养后,菌株HXS-01和HXS-02总硒和有机硒含量及产率、SPS活性和蛋白硒含量分别比出发菌株高3.4～4.0倍、2.9～3.5倍、0.7～1.1倍和0.9～1.1倍,且以菌株HXS-02的富硒能力更高,其总硒含量和产率分别为2 303.97 μg/g和7 945.19 μg/L,有机硒占总硒的百分比超过97%。利用H2O2作为一种新的选择压力可以有效筛选出具有高SPS活性的富硒酵母菌株。     

硒浓度梯度驯化结合紫外诱变法选育富硒酵母菌研究

为获得高产富硒酵母,通过硒浓度梯度驯化啤酒酵母Sac.cerevisiae Fec205、戴氏酵母Sac.delbrueckii Fec209、热带假丝酵母Candida tropicalis Fec2011等3株酵母菌,结果显示啤酒酵母Sac.cerevisiae Fec205比其他2株酵母的耐硒性能更强。因此以啤酒酵母Sac.cerevisiae Fec205为原始菌株进行紫外诱变以提高其富硒能力。通过硒抗性筛选,挑取出6株生长快、菌落大的突变菌株单菌落。取发酵培养基中生物量大的3株酵母菌Sac.cerevisiae Y-3,Y-4,Y-1,接种于硒浓度为40μg/ml发酵培养基,结果显示选育出的3株诱变后的啤酒酵母Sac.cerevisiae Y-3,Y-4,Y-1的硒含量分别为932、832、915μg/g,其中最高的Y-3比原始菌株啤酒酵母Sac.cerevisiae Fec205的硒含量增长50.08%、生物量提高了50.97%。     

富硒酵母中硒蛋氨酸的GC-MS/MS测定

建立酵母中硒蛋氨酸含量的气相色谱——串联质谱法(GC-MS/MS)分析方法。比较3种富硒酵母中硒蛋氨酸检测样品的提取方法,优化硒蛋氨酸的酶解提取条件;以氯甲酸乙酯为衍生化试剂,2-氯苯丙氨酸为内标物,采用选择离子模式对衍生物进行GC/MS/MS检测。结果表明,硒蛋氨酸的回收率为90.0%～97.0%,检测限为4μg/L,方法精密度(RSD)为7.8%。该方法简单快捷、定量准确、灵敏度高。     

富硒益生菌的筛选及其富硒条件的优化

为了获得能耐受较高亚硒酸钠质量浓度和具有富硒能力的益生菌菌株,对7株酵母菌和12株乳酸菌进行了筛选。结果表明,所有菌株均能在亚硒酸钠质量浓度为20~80μg/m L的平板上生长,乳酸菌YQRS菌株和酵母菌FJYJM3菌株具有较高的耐受性和富硒能力。对它们进行发酵条件的优化,表明YQRS菌株在亚硒酸钠添加量为15μg/m L、添加硒的时间为对数期前期时,富硒效果最好,菌体生物量为2.66 g/L,总硒含量能达到2 300.26μg/L。而FJYJM3菌株在亚硒酸钠添加量为20μg/m L,添加硒的时间为对数期前期时,富硒效果最显著,生物量能达到4.86 g/L,总硒含量能达到5 790.99μg/L。     

鸡腿菇菌丝深层培养富硒的研究

通过正交试验,从4株鸡腿菇菌株中筛选出1株具有较高生物量和较强富硒能力的鸡腿菇菌株CcⅢ,并探讨了其耐硒和富硒特性。结果表明,CcⅢ菌株具有一定的耐硒能力和很强的富硒能力,其固态培养最大耐硒浓度为10μg/mL,液态培养最大耐硒浓度为4μg/mL。在硒浓度2μg/mL时,菌丝体生物量为4.11 g/L,富硒量246.74μg/g,富硒率为50.57%,有机化程度高达92.95%。     

富硒酵母的分离鉴定及富硒条件的优化

富硒酵母生产发酵食品是补充硒元素的有效方法,以实验室保存的酵母菌为材料,通过选择培养基平板稀释法,分离纯化得 到四株富硒酵母,经形态学和分子生物学鉴定,初步鉴定菌株Z4、Z5、Z7、Z9均为库德毕赤酵母（Pichia kudriavzevii）。 通过对比四株菌 的生长曲线及富硒能力,发现Z5菌株生长状况最好,选取接种量、碳源（葡萄糖）和氮源（蛋白胨）添加量作为单一因素,通过单因素 试验和正交试验,探究各影响因素对菌株Z5富硒能力的影响。 结果表明,Z5菌株的最佳富硒发酵条件为接种量10%,葡萄糖2.4%,蛋 白胨1.8%。 在此最佳条件下,菌株Z5生物量为9.63 g/L,总硒含量可达到862 μg/g。     

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.     

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.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press