黑曲霉DB056发酵α-鼠李糖苷酶和柚苷酶培养基的优化研究

目的:优化黑曲霉DB056产α-鼠李糖苷酶和柚苷酶的培养基,提高这两种醇的产量.方法:以α-鼠李糖苷酶活力和柚苷酶活力为指标,研究碳源、氯源和乳化剂Triton X-100对α-鼠李糖苷酶活力和柚苷酶活力的影响,优化黑曲霉DB056摇瓶发酵α-鼠李糖苷酶和柚苷酶的培养基.结果:碳氮源的种类与浓度,乳化剂Triton X-100的浓度对黑曲霉DB056产α-鼠李糖苷酶和柚苷酶有重要影响;黑曲霉DB056产酶的优化培养基是:柚皮苷3.5 g/L,玉米浆4g/L,MgSO4·7H2O 1.0g/L,KH2PO41.0g/L,KCl 0.5 g/L,无水CaCl20.1 g/L,乳化剂Triton X-1001.0%.此时α-鼠李糖苷酶活力和柚苷酶活力分别为994U/mL和276U/mL,分别比发酵初始培养基提高了42.3%和147.8%.结论:通过培养基优化,大幅度提高了黑曲霉DB056液态深层发酵α-鼠李糖苷酶活力和柚苷酶活力.     

黑曲霉DB056发酵产柚苷酶中试放大研究

对在实验室筛选得到的产柚苷酶菌株黑曲霉DB056进行7、20和200L规模的逐级发酵放大研究.采用高效液相色谱法测定柚苷酶的活力.试验结果表明:随着发酵规模的增大,柚苷酶的两种组分——α-鼠李糖苷酶与β-葡萄糖苷酶的酶活力水平有一定的波动,但酶活力变化基本一致;在200 L规模的发酵中,α-鼠李糖苷酶与β-葡萄糖苷酶的最大酶活力分别为1 069 U/mL和727 U/mL,超过7L和20 L规模发酵过程中柚苷酶的活力水平,从而实现了黑曲霉DB056产柚苷酶200L规模的发酵,显示出该菌株良好的发酵性能和工业应用价值.     

溶氧状况对黑曲霉DB056产柚苷酶的影响研究

以α-L-鼠李糖苷酶和柚苷酶的酶活为评价指标,从装液量、玻璃珠数量、氧载体这3个方面来研究黑曲霉DB056摇瓶发酵产柚苷酶的溶氧条件。通过单因素优化得到的摇瓶发酵条件为:装液量35mL、玻璃珠添加个数为3个(直径4mm)、最适氧载体为1%正己烷,在此条件下α-鼠李糖苷酶活力最大可达787.8U/mL,柚苷酶活力最大可达232.5U/mL。     

α-L-鼠李糖苷酶发酵过程放大研究——从5L到30L发酵罐

以产α-L-鼠李糖苷酶(α-L-1,2-鼠李糖苷酶和α-L-1,6-鼠李糖苷酶)的黑曲霉As-pergillus niger WZ001为考察对象,研究了从5L发酵罐到30 L发酵罐的通气量和搅拌转速的放大工艺.通气量按三种准则、搅拌转速按两种准则放大.通过实验验证,优选得到最佳放大准则为:通气量按1.5倍空气表观线速度进行放大、搅拌转速按搅拌桨叶尖线速度放大.在该优化的放大工艺条件下,30 L发酵罐中α-L-1,2-鼠李糖苷酶和α-L-1,6-鼠李糖苷酶的产量分别为2 515 U/mL和3 612 U/mL,达到5L发酵罐的水平.     

Aspergillus niger S-05产柚苷酶液态发酵条件的优化

通过单次单因素试验对黑曲霉(Aspergillus nigerS-05)液体发酵的产柚苷酶条件进行优化,结果表明,当培养条件为豆粉2.0%、蔗糖0.5%、柚苷0.05%、MgSO4·7H2O 0.6%、吐温-80 0.2%、培养温度26℃、初始pH 5.0、250 mL三角瓶装量30mL、转速190r/min、培养时间105 h时柚苷酶酶活达到最高值(429.09U/mL).同时发现,通过调节培养基组成可改变所产柚苷酶中α-L-鼠李糖苷酶和β-D-葡萄糖苷酶的酶活比例,从而实现根据不同应用进行有针对性的发酵产酶控制目的.     

黑曲霉菌丝体活力对α-L-鼠李糖苷酶发酵的影响

α-L-鼠李糖苷酶是工业上一种重要的水解酶。为了方便地优化和监控α-L-鼠李糖苷酶的发酵生产过程,在5 L发酵罐水平研究黑曲霉菌丝体活力与α-L-鼠李糖苷酶产量之间的关系,菌丝体活力采用TTC-脱氢酶法进行测定。实验结果表明,在发酵过程中维持适宜的菌丝体活力对α-L-鼠李糖苷酶的产量非常重要:当摇瓶种子菌丝体活力达到最大值0.388 U/mL时,对应的5 L发酵罐中α-L-鼠李糖苷酶的产量最大;控制发酵过程的pH恒定于5.5,可以有效延缓菌丝体活力下降速度,使α-L-鼠李糖苷酶的产量提高28.7%;当搅拌转速低于400r/min或通气量低于0.3 vvm时,发酵24～36 h的菌丝体活力大幅下降,α-L-鼠李糖苷酶的产量显著降低。因此,可以将菌丝体活力作为α-L-鼠李糖苷酶发酵工艺优化和生产过程控制中一项重要的监控参数。     

黑曲霉S-05产柚苷酶液态发酵培养条件的优化

以黑曲霉(Aspergillus niger S-05)菌株作为实验材料,采用摇瓶发酵方法,以α-L-鼠李糖苷酶、β-D-葡萄糖苷酶、柚苷酶三酶酶活为评价指标,对其液态发酵条件进行了研究.优化后的培养条件为:2.0%豆粉、0.5%蔗糖、0.05%柚苷、0.6%MgSO4·7H2O、0.2%吐温-80、培养温度26℃、pH5.0,250mL三角瓶装量30mL、转速190r/min.此时柚苷酶酶活达到429.09U/mL,比优化前的基础培养基(137.78 U/mL)提高了2.1倍.     

柚苷酶固体酶制剂制备及贮藏稳定性的研究

以黑曲霉DB056发酵液为原料,研究柚苷酶固体酶制剂的制备工艺及其贮藏稳定性。结果表明:柚苷酶发酵液经预处理、浓缩、喷雾干燥后制成柚苷酶固体酶制剂。硫酸铵沉淀和乙醇沉淀对柚苷酶活力影响较大,α-鼠李糖苷酶和β-葡萄糖苷酶的回收率较低;超滤浓缩法对柚苷酶活力影响较小,不同浓缩倍数的粗酶液α-鼠李糖苷酶和β-葡萄糖苷酶的回收率均很高,大于97%。温度、空气和湿度对柚苷酶固体酶制剂稳定性影响较大,光照和紫外线对其稳定性影响较小。实际应用中,柚苷酶固体酶制剂应尽可能低温真空保存。     

碳源及阻遏蛋白CreA对黑曲霉产α-L-鼠李糖苷酶的影响

【目的】研究碳源对黑曲霉JMU-TS528发酵α-L-鼠李糖苷酶的影响,并探讨葡萄糖阻遏黑曲霉合成α-L-鼠李糖苷酶的分子机制。【方法】分别用5种单一碳源进行摇瓶发酵,高效液相色谱法测定经黑曲霉发酵后产物中的α-L-鼠李糖苷酶活性;通过在培养基中添加葡萄糖进行液态发酵,研究葡萄糖对黑曲霉JMU-TS528产α-L-鼠李糖苷酶的影响,并用实时定量PCR技术检测α-L-鼠李糖苷酶基因rha和葡萄糖抑制基因Cre A的相对表达量。【结果】黑曲霉JMU-TS528在以柚皮苷、橘皮苷、芸香苷和鼠李糖为唯一碳源时可分泌α-L-鼠李糖苷酶,以葡萄糖为唯一碳源时不能合成α-L-鼠李糖苷酶;培养基中添加葡萄糖后,黑曲霉发酵产物中α-L-鼠李糖苷酶活性降低,黑曲霉α-L-鼠李糖苷酶基因rha表达量降低,而葡萄糖抑制基因Cre A表达量上升。【结论】黑曲霉JMU-TS528菌株液态发酵条件下合成α-L-鼠李糖苷酶需要诱导物作为碳源,该菌株合成α-L-鼠李糖苷酶的能力受到葡萄糖的调节作用,此调控过程可能通过一个依赖阻遏蛋白Cre A的机制实现。     

产柚苷酶黑曲霉SL2K发酵条件优化

该研究以黑曲霉（Aspergillus niger）SL2K为研究对象,对其产柚苷酶的液态发酵条件进行优化。 通过单因素试验对碳源、氮 源、诱导物、接种量、初始pH值和培养时间进行考查,在单因素基础上,选取麸皮粉添加量、蛋白胨添加量、接种量、初始pH值4个因素 进行4水平正交试验优化。 结果表明,优化后的产酶发酵条件为麸皮粉添加量3%,蛋白胨添加量5%,接种量8%,初始pH值为5.0,鼠李 糖0.08%、KH2PO4 1 g/L,KCl 0.5 g/L,MgSO·4 7H2O 0.5 g/L,FeSO4 0.01 g/L,装液量为100 mL/250 mL,摇床转速180 r/min,培养温度28 ℃, 培养时间96 h。 在此优化条件下,柚苷酶活力为233.89 U/mL,是优化前的2.13倍。     

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