MPMS诱变结合抗生素抗性选育多杀菌素高产菌株

采用多功能等离子体诱变系统(MPMS)对菌株ASAGF 13-8-1进行诱变,并通过链霉素、庆大霉素、利福平、氯霉素四种抗生素抗性筛选多杀菌素高产菌株。利用96孔板发酵培养结合生物检测的快速方法进行高产菌株高通量初筛,摇瓶发酵进行复筛。通过5轮复筛验证,获得1株产量较出发菌株提高28.68%且遗传稳定的突变菌14-2。比较MPMS诱变和MPMS诱变结合0.9μg/mL链霉素、14μg/mL庆大霉素、400μg/mL利福平、2μg/mL氯霉素的四重抗性筛选对出发菌株ASAGF 13-8-1的作用效果,结果显示MPMS诱变结合抗生素抗性筛选更有利于多杀菌素高产菌株的选育。     

利用混料设计优化多杀菌素发酵培养基

利用Plackett-Burman试验设计从8种营养成分中筛选出4种对多杀菌素产量影响较显著的因子:葡萄糖、棉籽粉、玉米浆、豆饼粉,而后通过D-最优混料设计,对这4种成分进行优化设计。以多杀菌素的产量为期望,进行回归分析并建立关于多杀菌素产量的二阶拟合方程,确定4种成分的最佳比例为:葡萄糖59 g/L、棉籽粉28 g/L、玉米浆6.5g/L、豆饼粉6.5g/L,根据方程预测产量理论最高值为256.75mg/L,按此配方进发酵验证,产量为249.9mg/L,证明该方程的拟合性较好。     

可得然胶补料发酵工艺优化

在15L发酵罐中考察了连续补料、分批补料、半连续补料Ⅰ和半连续补料Ⅱ4种补料方式对土壤杆菌No.25产可得然胶的影响。结果表明,发酵48h后,通过调控放料补料体积和时间,能有效降低发酵液粘度,提高可得然胶生产效率。连续补料效果最差,半连续补料优化Ⅱ效果最好。半连续补料Ⅱ工艺可得然胶产量为48.78g/L,是连续补料产量的1.69倍;转化率为50.5%,是连续补料的1.83倍;生产强度达到0.51g/L/h,比产胶速率达到0.093g/h/g-cell。半连续补料Ⅱ工艺为:发酵48h时放料1L,一次性补加蔗糖溶液1L;72h放料1L,一次性补水1L。     

原生质体融合选育多杀菌素高产菌株

实验以刺糖多孢菌CB11(Saccharopolyspora spinosa CB11)与红霉素高产菌株红色糖多孢菌E2(Saccharopolyspora erythraea E2)为亲本进行种间原生质体融合,通过对两亲本原生质体的不同灭活条件的考察,确定了S.spinosa CB11的热灭活条件为60℃水浴45 min,S.erythraea E2的紫外灭活条件为20 W紫外灯30 cm处,照射1 min。实验还优化了S.spinosa CB11与S.erythraea E2原生质体进行种间的最佳融合条件:室温下采用50%PEG 1 000融合3～5 min。融合子经多杀菌素的摇瓶发酵发现,融合子正突变率达到57.1%,其中遗传稳定性良好的高产融合子S.spinosa X9的多杀菌素产量可达290μg/mL,比亲本S.spinosa CB11(产量为153μg/mL)提高了89.5%。所有研究结果表明原生质体种间融合技术在刺糖多孢菌多杀菌素高产菌株选育中的应用是可行的、高效的。     

脂肪酶抑制剂Lipstatin的发酵罐发酵工艺优化

研究了溶氧和剪切力对毒三素链霉菌(Streptomyces tocytricini)发酵产生Lipstatin的影响,并对Lipstatin发酵从摇瓶到10 L发酵罐的放大及补料工艺进行了研究。根据Lipstatin菌株发酵溶氧要求高、对剪切力敏感的特性及高油培养基质地黏稠的特点,优化了Lipstatin 10 L全自动发酵罐的搅拌工艺、通气量并建立合适的补料工艺,改善Lipstatin发酵过程中的溶氧水平。Lipstatin 10 L发酵罐发酵效价达到6 446μg/mL,比摇瓶发酵效价提高约40%,发酵周期缩短1 d。     

基于响应面法优化谷氨酸棒杆菌发酵条件

该研究以谷氨酸棒杆菌（Corynebacterium glutamicum）P169为研究对象,以谷氨酸产量为主要评价指标,采用单因素试验和响应面法对其发酵条件进行优化,并进行摇瓶和20 L罐分批补料发酵验证。结果表明,谷氨酸棒杆菌P169产谷氨酸的最佳发酵条件为酵母粉41.0 g/L、葡萄糖27.0 g/L、尿素12.0 g/L和pH 7.0。在此优化条件下,谷氨酸产量达25.1 g/L,比优化前（16.5 g/L）提高了52.1%。以此为基料进行20 L罐分批补料发酵,谷氨酸产量达155 g/L,比优化前（142 g/L）提高了9.2%。该研究为提高谷氨酸棒杆菌谷氨酸产量提供了一种技术解决方案。     

地衣芽孢杆菌HDYM-04产β-甘露聚糖酶补料分批发酵条件优化

利用地衣芽孢杆菌(Bacillus licheniformics)HDYM-04在5L发酵罐中发酵生产β-甘露聚糖酶,并对其发酵条件、补料策略及用量进行优化。得到最优起始魔芋粉加入量、初始pH值和接种量分别为60g/L、8.0和6.7%;最佳发酵工艺为:温度37℃,搅拌速率300r/min,通气量3L/min,发酵48h。最后确定最佳补料策略为起始加入30g魔芋粉,对数生长后期再加入90g魔芋粉,最终酶活力可高达3913U/mL,较未优化前(2070U/mL)酶活力提高了89%。     

响应面法优化根霉菌产麦角固醇的液体发酵工艺

以米根霉(Rhizopus oryzae ZW017)发酵产麦角固醇的产量为响应值,对其液体发酵工艺进行优化。采用HPLC法检测菌株产麦角固醇含量,在单因素筛选试验基础上,以PDB液体发酵培养为基础条件,应用响应面分析法(RSM)对碳源、氮源及发酵时间进行优化。结果表明:以葡萄糖、酵母膏分别为最佳碳、氮源;最佳工艺条件为:PDB基础培养基中添加葡萄糖3g/L、酵母膏5g/L、发酵培养9.64d,麦角固醇平均产量达5761.83μg/100mL,较优化前提高了247.86%,与构建模型理论预测值(5818.39μg/100mL)相吻合,且100mL液体培养基中麦角固醇产量占菌体细胞干质量(0.36g)的1.60%。     

费氏丙酸菌HZ-P-35细胞高密度培养转化亚油酸生成共轭亚油酸

对费氏丙酸杆菌HZ-P-35高密度培养转化亚油酸生成共轭亚油酸进行了研究.共轭亚油酸(CLA)的测定以十七碳烯酸作内标物经甲酯化后采用气相色谱法测定.采用间歇培养、pH-stat培养、间歇补料培养和连续补料培养四种培养方式进行细胞高密度培养实验.pH-stat培养、间歇补料和连续补料都大大地提高了菌体密度和CLA产量.相对于间歇培养,采用pH-star培养模式丙酸菌细胞干重提高1.5倍,达到1.2g/L;而间歇补料培养和连续补料培养的细胞干重分别提高3.4倍和2.97倍,分别达到2.72 g/L和2.38 g/L.pH-stat培养模式CLA产量是间歇培养的1.06倍,达到114.50μg/mL,间歇补料培养CLA产量是间歇补料培养的1.17倍,达到127.34μg/mL,连续补料培养模式CLA的产量是间歇培养CLA量的1.29倍,达到139.67μg/mL.试验结果表明,间歇补料培养较有利于细胞高密度培养,细胞产率达到9.074 mg/(L·h),而连续补料培养较有利于CLA产生.     

枯草芽孢杆菌产碱性果胶酶发酵条件的优化

通过单因素实验对枯草芽孢杆菌菌株发酵产碱性果胶酶的培养基组分及培养条件进行优化。利用单因素实验确定了产酶的最优培养基:30 g/L豆饼粉、35 g/L马铃薯淀粉、20 g/L果胶、2.775 g/L氯化钙、4.025 g/L硫酸锌、113.6 g/L Na 2HPO 4。同时对温度、接种量、发酵pH进行优化,得到最优发酵条件:温度35℃、接种量3%、发酵过程控制pH=7.4,在此基础上进行补料流加实验,补料配方为350 g/L葡萄糖、10 g/L果胶,补料控制总糖浓度为20 ug/mL,并调整转速和风量控制溶氧30%~40%,最终酶活达到6120 U/mL,较初始酶活1061 U/mL提高了4.77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.     

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.     

Textural Properties of Cold-set Gels Induced from Heat-denatured Whey Protein Isolates

A 9% whey protein (WP) isolate solution at pH 7.0 was heat-denatured at 80°C for 30 min. Size-exclusion HPLC showed that native WP formed soluble aggregates after heat-treatment. Additions of CaCl2 (10–40 mM), NaCl (50–400 mM) or glucono-delta-lactone (GDL, 0.4–2.0%, w/v) or hydrolysis by a protease from Bacillus licheniformis caused gelation of the denatured solution at 45°C. Textural parameters, hardness, adhesiveness, and cohesiveness of the gels so formed changed markedly with concentration of added salts or pH by added GDL. Maximum gel hardness occurred at 200 mM NaCl or pH 4.7. Increasing CaCl2 concentration continuously increased gel hardness. Generally, GDL-induced gels were harder than salt-induced gels, and much harder than the protease-induced gel.     

Occurrence of bisphenol-F-diglycidyl ether (BFDGE) in fish canned in oil

The levels of bisphenol-F-diglycidyl ether (BFDGE) were quantified as part of a European survey on the migration of residues of epoxy resins into oil from canned fish. The contents of BFDGE in cans, lids and fish collected from all 15 Member States of the European Union and Switzerland were analysed in 382 samples. Cans and lids were separately extracted with acetonitrile. The extraction from fish was carried out with hexane followed by re-extraction with acetonitrile. The analysis was performed by reverse phase HPL C with fluorescence detection. BFDGE could be detected in 12% of the fish, 24% of the cans and 18% of the lids. Only 3% of the fish contained BFDGE in concentrations considerably above 1mg/kg. In addition to the presented data, a comparison was made with the levels of BADGE (bisphenol-A-diglycidyl ether)analysed in the same products in the context of a previous study.     

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.     

Contribution of European research to risk analysis

The European Commission's, Quality of Life Research Programme, Key Action 1—Health, Food & Nutrition is mission-oriented and aims, amongst other things, at providing a healthy, safe and high-quality food supply leading to reinforced consumer confidence in the safety of European food. Its objectives also include the enhancing of the competitiveness of the European food supply. Key Action 1 is currently supporting a number of different types of European collaborative projects in the area of risk analysis. The objectives of these projects range from the development and validation of prevention strategies including the reduction of consumers risks; development and validation of new modelling approaches; harmonization of risk assessment principles, methodologies, and terminology; standardization of methods and systems used for the safety evaluation of transgenic food; providing of tools for the evaluation of human viral contamination of shellfish and quality control; new methodologies for assessing the potential of unintended effects of genetically modified (genetically modified) foods; development of a risk assessment model for Cryptosporidium parvum related to the food and water industries; to the development of a communication platform for genetically modified organism, producers, retailers, regulatory authorities and consumer groups to improve safety assessment procedures, risk management strategies and risk communication; development and validation of new methods for safety testing of transgenic food; evaluation of the safety and efficacy of iron supplementation in pregnant women; evaluation of the potential cancer-preventing activity of pro- and pre-biotic ('synbiotic') combinations in human volunteers. An overview of these projects is presented here.     

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