乳酸菌融合菌株的构建及其特性研究

用具有良好产黏活性的瑞士乳杆菌SR288 与产酸力强的保加利亚乳杆菌NR902 已灭活的原生质体电融合,构建高活性乳酸菌菌株。研究表明最佳电融合参数为：交变电场强度300V/cm,脉冲强度6kV/cm,脉冲时间40μs,脉冲个数4 个。融合菌株能连续稳定遗传10 代,生物活性检测表明,其产酸能力、表观黏度、持水力均优于亲株。     

原生质融合选育高产赤藓糖醇菌株的研究

在实验室经紫外诱变方法筛选到28株赤藓糖醇产生菌优良菌株基础上,采用原生质体电融合技术构建高产赤藓糖醇工程菌,对在实验过程中影响原生质体形成的各种因素以及影响电融合的各项参数进行初步研究,研究表明:酶解浓度为0.25%,酶解时间为20min,酶最适宜作用温度为35℃,最适pH值5～6。确定了最佳融合参数:交变电场强度为250V/cm,脉冲强度为6kV/cm,脉冲时间为30μs,脉冲个数为5个。融合菌株赤藓糖醇产量为120.6g/ml,葡萄糖转化率为53.2%。     

米根霉原生质体电融合条件研究

以米根霉突变株mut-A、mut-B为亲本,采用双亲灭活标记筛选融合子,对亲本灭活条件、原生质体电融合条件进行了研究。实验结果表明,0.6mol/L山梨醇溶液为最适的渗透压缓冲液,mut-A、mut-B的灭活条件分别为50℃加热6min及紫外照射180s。原生质体在电场中排队所需的细胞浓度为1×107/mL,交变电场电压为8V;最佳的电融合参数为直流脉冲电压260V,脉冲持续时间40μs,脉冲次数2次;最高融合率可达7.29±0.71%。     

茶树菇与鸡腿菇原生质体融合及再生

研究茶树菇与鸡腿菇原生质体制备、融合及再生。以菌龄4d 的菌丝体为原料,采用1% 果胶酶和1% 蜗牛酶混合酶液(体积比1:1),酶解4h,酶解温度为30℃,pH6.0 的0.6mol/L 甘露醇溶液为渗透压稳定剂,制备得到茶树菇与鸡腿菇原生质体。两种原生质体融合的最佳条件为：使用35% 聚乙二醇(PEG4000)和0.2mol/L CaCl₂ 溶液(pH10)为助融剂,30℃融合30min。利用灭活原生质体作为标记筛选出融合子,融合的细胞在培养基中实现再生,通过菌落表型的比较和拮抗实验验证再生出的为融合子。     

原生质体电融合法构建葡萄酒降酸酵母的研究

以发酵性能优良的葡萄酒酵母F83和具有降解苹果酸能力的酒类酒球菌作为亲本菌株,进行电融合,构建发酵性能良好且具有降解苹果酸能力的葡萄酒酵母菌株.结果表明,两亲本菌株原生质体电融合的最佳条件为:交变电压55 V,交变电场频率1000 kHz,脉冲宽度30μs,脉冲个数5个.共获得13株融合株,其中10号融合子发酵、降酸性能较佳.     

同种接合型酵母菌株Y2HGold的原生质体融合研究

为避开有性融合的局限性,挖掘同种接合型酵母菌株无性融合的潜在应用价值,利用质粒构建了酵母双杂交工程菌株Y2HGold的亮氨酸缺陷型和色氨酸缺陷型菌株;接着采用酶解法进行四因素三水平正交实验获得原生质体制备方案:酶解温度30℃、处理时间80min、预处理剂含0.1%(w/v)巯基乙醇和0.1%(w/v)EDTA-2Na,酶解液为1.5%(w/v)蜗牛酶和1.5%(w/v)纤维素酶混合,使得原生质体的制备及再生率分别达82%和37%;最后采用PEG诱导融合的方法,经过同样正交实验得到Y2HGold无性融合条件为:PEG浓度35%、温度25℃、时间40min、pH5.8。筛选得到的无性融合子在遗传上稳定。     

双亲灭活电融合技术选育酱油生产菌株

选择互补且各具优势的2株米曲霉A98和A33为出发菌株,研究了其原生质体制备和电融合条件.接种YPD液体培养基,30℃摇瓶培养11h获得菌丝.以0.6mol/L甘露醇为渗透压稳定剂,最佳破壁酶液为溶壁酶∶蜗牛酶∶纤维素酶=1∶1∶1,浓度为10mg/mL,28℃酶解2.5h时原生质体浓度达到108个/mL,再生率≥20％;最佳电融合条件为1MHz交流频率,交流场强300V/cm,直流场强6kV/cm,脉冲间隔60μs,脉冲个数3;在此条件下,电融合率达到10-5.对获得的融合子进行酱油发酵筛选,以原料收得率为关键考察指标,筛选获得了1株融合子F01-008,其原料收得率较亲本较高者提高了5.61％.     

电融合原生质体构建麦角甾醇酵母菌株的研究

实验采用细胞电融合技术进行麦角甾醇酵母菌株构建研究,在不同种属的酵母菌种进行筛选研究,确定麦角甾醇含量较高酿酒酵母(Saccharomyces cerevisiae)和细胞生物量较高产朊假丝酵母(Candi-dautilis)为亲本菌株,进行原生质体制备、原生质体再生、原生质体灭活和原生质体融合研究,确定电融合过程中电压、脉冲强度、脉冲间隙及脉冲次数等技术参数,并筛选出融合子PF-4。经发酵性能实验表明,PF-4的细胞生物量为33.17g/L,麦角甾醇含量为2.01%,均高于亲本菌株,为玉米发酵法制备麦角甾醇酵母提供生产菌株。     

灵芝菌原生质体融合条件研究

通过化学方法和电融合法对白芝(Ganoderma applanatum,GA)和赤芝(Ganoderma lucidum,GL)两种大型真菌原生质体融合条件进行了研究,实验得出:化学方法对灵芝菌原生质体融合的最佳条件:PEG浓度30%、CaCl20.02mol/L、融合时间30min、温度30℃,融合率可达0.4%;电融合法对灵芝菌原生质体融合的最佳条件:交变电流频率2MHz、电压40V、直流脉冲脉幅10kV/cm、脉宽25μs、直流电压为500V,融合率可达40%。     

秦巴山区黑木耳主要栽培种内原生质体分离与融合

采用单一变量法研究了黑木耳神农A8与秦单4#原生质体的制备、再生及融合的最佳条件。培养7 d的黑木耳菌丝体用0.5 mol/L甘露醇做稳渗剂,2.0 mol/L的溶壁酶酶解,30℃下水浴3.5 h时,黑木耳神农A8和秦单4#原生质体释放量分别达到0.94×107、1.44×107个/mL;选择RM5再生培养基,神农A8和秦单4#原生质体再生率最高,分别为1.91%、1.53%;原生质体融合的最佳条件为:使用30%聚乙二醇(PEG4000)和0.05 mol/L CaCl2溶液(pH 10)为助融剂,35℃融合30 min。通过荧光镜检和撷抗反应得到融合子,为黑木耳的遗传育种奠定理论基础。     

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.     

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.     

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%.