乳酸乳球菌食品级双筛选标记的分泌型表达载体的构建

纤维素酶在畜牧业、饲料工业、生物技术和生物能源利用方面均有广泛应用。纤维素酶基因工程作为研究的重点,可以提高酶产量和稳定性,具有广阔的应用前景。通过利用基因工程技术改造pMG36e载体,成功构建出具有双筛选标记的外分泌表达纤维素酶的食品级重组质粒,完成载体构建;然后将该质粒转化到粪肠球菌19855株并实现基因表达,经测定,分泌的纤维素酶活力为0.92 U/mL。该研究结果为后续食品级工程菌的进一步研制奠定了基础。     

不同添加剂对籽粒苋与油菜秸秆混合青贮品质的影响

在72%籽粒苋与28%油菜秸秆的混合青贮中分别添加糖蜜、乳酸菌、纤维素复合酶、糖蜜+乳酸菌、糖蜜+纤维素复合酶、乳酸菌+纤维素复合酶、糖蜜+乳酸菌+纤维素复合酶和水,青贮30d后开包取样,并分析各项指标。结果表明:籽粒苋与油菜秸秆混合青贮时,与对照组和非添加糖蜜组相比,单独或组合添加糖蜜均能显著降低籽粒苋与油菜秸秆混合青贮的pH值、乙酸含量、洗涤纤维含量,并能显著提高其V–Score评分、粗蛋白含量、可溶性碳水化合物含量及相对饲用价值。籽粒苋与油菜秸秆混合青贮中单独添加糖蜜即可保证青贮品质效果。     

非密闭系统中芦笋老茎的水解特性研究

非密闭系统可为有机固体废物的生物水解提供兼氧环境,有效提高纤维素水解效率。探讨蔬菜废弃物芦笋老茎在非密闭系统中的水解情况,考查接种量和曝气操作对纤维素水解和腐殖质类物质生成的影响。结果表明:接种纤维素菌剂可加速芦笋老茎的分解,且以接种比0.3%为最优,芦笋老茎最高的总固体分解率和纤维素降解率分别为75.43%和51.03%。红外光谱和三维荧光光谱揭示了水解过程中纤维素和腐殖质类物质的演化特征。腐殖化指数(HIX)和荧光指数(FI)表明,接种菌剂和增加曝气可以进一步提高水解产物的腐殖化程度。水解产物的HIX与发芽指数呈正相关,12 d后水解液中最高的发芽指数为93.2%,说明这种非密闭兼氧水解过程可独立应用于芦笋老茎的减量化处理。     

果蔬保鲜包装技术及其研究进展

果蔬保鲜包装技术是一类应用性较强的现代保鲜技术,该技术能够更好地保持产品品质,降低果蔬损耗率。在过去的几十年,果蔬保鲜包装技术得到了较快的发展。近年来,随着生鲜电子商务新业态的出现及快速发展,消费者对果蔬品质的要求不断提高,使得市场对保鲜包装性能提出了新需求,这就促使果蔬保鲜包装技术呈现出更多元化的发展趋势。本文介绍了气调包装、活性包装和智能包装等果蔬包装技术的概念及原理,综述了其研究进展,并对果蔬保鲜包装技术进行了展望。     

Generation of pigs with a Belgian Blue mutation in MSTN using CRISPR/Cpf1-assisted ssODN-mediated homologous recombination

CRISPR/Cpf1 has emerged recently as an effective tool for genome editing in many organisms, but its use in pigs to generate precise genetic modifications has seldom been described. Myostatin(MSTN) is a well-characterized negative regulator of muscle development, and natural mutations in this gene cause a double-muscled phenotype in many species. However, to the best of our knowledge, no naturally occurring mutation in MSTN has been found in pigs. In addition, no living pig models with sophisticated modifications orthologous to natural mutations in MSTN have yet been reported. In this study, we exploited the CRISPR/Cpf1 system to introduce a predefined modification orthologous to the natural MSTN mutation found in Belgian Blue cattle(thus known as the Belgian Blue mutation). Our research demonstrated that the cutting efficiency of CRISPR/Cpf1 was 12.3% in mixed porcine fetal fibroblasts in drug free medium, and 41.7% in clonal colonies obtained using G418 selection. Then, the Cpf1-sgRNA vector, ssODN template, and a self-excision cassette were co-transfected into porcine fetal fibroblasts. After G418 selection, 8 clonal colonies were examined and 5 with genetic modification were found. Of these 5, 2 harbored the precise 11-bp deletion. Using 1 heterozygous clonal colony, 2 cloned Duroc piglets were successfully generated, which was heterozygous for the Belgian Blue mutation. In summary, our results demonstrate that CRISPR/Cpf1 system can be used efficiently to generate double-stranded breaks, and also to mediate homologous recombination to introduce precise genomic modifications in pigs.     

不同保水剂施用量对烟草生长品质的影响

为了探究保水剂对烟草生长品质的影响,明确保水剂的最佳施用量,本试验研究不同保水剂施用量对山东淄博沂源烟草生长品质的影响。结果表明,该地区烟田保水剂施用量为180 kg/hm2对提高烟叶品质和经济性状的效果较为明显。     

由两种功能膜组成的气调包装设计及其在鲜枸杞保鲜上的应用

本文设计了一款新型气调保鲜包装(MAP),并且在常温下(25℃)评价了其对鲜枸杞的保鲜效果。新型气调保鲜包装由两种功能薄膜拼接而成,其中一种功能薄膜(OPF)具有高氧气透过性和高水蒸气阻隔性,另一种功能薄膜(WPF)具有高水蒸气透过性和高氧气阻隔性。由这两种功能薄膜组成的气调保鲜包装(T-MAP)中,OPF能够调节包装内氧气浓度,而WPF能调节包装内相对湿度(RH)。根据鲜枸杞的呼吸耗氧量、设定的包装内适宜的氧气浓度和OPF功能薄膜的氧气透过率(OTR)可以计算出OPF薄膜的面积;根据鲜枸杞呼吸时水分的生成量、设定的包装内适宜的相对湿度和WPF功能薄膜的水蒸气透过率(WVTR)可以计算出WPF薄膜的面积。两片功能薄膜粘合后制成盖膜,热合在果盒上形成T-MAP包装,包装内形成一个低氧气浓度(5%左右)和高RH(95%左右)的环境条件,常温下可以将枸杞鲜果的货架期由对照组的2 d延长到6 d,且最大限度维持了枸杞的品质。     

谷子种子高质量总RNA提取方法的优化

为得到高质量的谷子种子RNA,本研究以5个不同谷子品种为材料,对RNAiso Plus法、改良RNAiso Plus法、CTAB法提取的RNA进行质量和纯度的比较。结果表明,改良RNAiso Plus法提取的总RNA完整性、纯度、浓度均优于其他2种方法提取的总RNA,5个不同谷子品种和不同萌发时期的谷子均可用改良RNAiso Plus法提取出高质量、完整性好的RNA,所得RNA产物可用于构建cDNA文库和转录组测序等后续试验。本研究为禾谷类植物种子的总RNA提取提供了一定的参考,也为谷子种子后续的分子生物学试验奠定了基础。     

Quantification of dietary DNA in tissues of Atlantic salmon (Salmo salar L.) fed genetically modified feed ingredients

The impact of dietary DNA on metabolism and health of animals and humans has received little attention, except in the context of genetically modified organisms (GMOs) and horizontal gene transfer. In a series of studies, we have investigated the uptake and persistence of dietary DNA in Atlantic salmon (Salmo salar L.). The objective of this study was to investigate the uptake and persistence of dietary DNA of soybean and maize origin. A feeding experiment on salmon was started at late yolk sac stage and lasted for 7 months. The fish were randomly distributed in groups in indoor tanks and fed different types of feed. After the last feeding, the fish were starved for 24 h before samples were dissected. Using the polymerase chain reaction (PCR) amplification of short targets from the chloroplast ribulose‐1,5‐carboxylase large subunit (rbcL) gene present in some of the feed components, the uptake and transport of dietary DNA from plant ingredients to tissues could be studied. The dietary DNA, of plant origin, was found to be present in all tissues investigated and their concentrations were determined.     

Fe3+改性TiO2/玻璃纤维催化剂制备优化研究

以玻璃纤维网为载体,采用溶胶-凝胶法,以Fe3+对TiO2催化剂实施掺杂,经胶液配制、膜的涂覆与焙烧等工序,制备改性TiO2催化膜。通过正交实验,考察了Fe/Ti质量比、涂覆次数、升温程序等因素对改性后的TiO2薄膜光催化降解苯酚性能的影响。在选定各因素各水平下,对TiO2催化膜的影响因素主次顺序为:Fe/Ti质量比>焙烧温度>涂覆次数。最优条件为:Fe/Ti质量比=0.01%;焙烧温度=600℃;涂覆次数=3次。X射线衍射(XRD)分析表明,在最佳条件下制备的改性TiO2为锐钛矿型,平均粒径为14.5nm。