响应面法优化弗托氏葡糖酸杆菌产羟基乙酸工艺条件

为了构建一株可以生产乙醇酸的食品安全菌株,对枯草芽孢杆菌开展了代谢改造。本研究首先利用同源重组手段将外源异柠檬酸裂解酶基因aceA整合到了枯草芽孢杆菌基因组上,构建了出发菌株164MCT-GA,然后利用代谢工程手段进行了乙醇酸合成代谢优化。结果表明,整合外源异柠檬酸裂解酶基因aceA的出发菌株164MCT-GA可以实现以甘油为底物的乙醇酸从头合成,摇瓶发酵产量为0.114 g/L;在此基础上,过表达柠檬酸合成酶基因（citA）,加强前体物供应;过表达乙醛酸还原酶基因（yvcT）、敲除乳酸脱氢酶基因（ldh）、磷酸乙酰转移酶基因（pta）、乙酰-CoA转乙酰酶基因（mmgA、yhfs）,从而减少碳源损失并提高乙醇酸转化率,最终得到的工程菌GA3-52,其摇瓶发酵产量为0.572 g/L,是出发菌株的5倍以上,产率为0.175 g/g甘油,本研究首次在枯草芽孢杆菌中利用乙醛酸循环进行乙醇酸的从头合成,为食品安全菌高产乙醇酸的发酵生产奠定了基础。     

海洋黄杆菌来源岩藻多糖酶Fcn1的异源表达及酶学性质

为了寻找和挖掘降解岩藻多糖的新型酶,以从海带中筛选获得的一株可以降解岩藻多糖的海洋黄杆菌Flavobacterium sp. RC2-3为研究对象,对其进行了全基因组测序。通过与已报道的岩藻多糖酶氨基酸序列比对,并进行转录组学分析及实时荧光定量PCR验证,挖掘了1个可能的岩藻多糖酶基因,并将其命名为Fcn1。Fcn1基因全长1221bp,编码406个氨基酸,蛋白分子质量约为46.8kDa。通过引物设计、PCR扩增,将Fcn1基因克隆,进一步构建了Fcn1基因异源表达载体Fcn1-pET-28a(+),并将其成功地在大肠杆菌BL21(DE3)表达宿主中进行了诱导表达。所得重组酶Fcn1通过带有His标签的镍柱进行分离纯化,采用铁氰化钾法测定纯化酶酶解岩藻多糖的比酶活(332U/mg),纯化倍数为2.25。酶学性质研究表明,重组酶Fcn1最适反应温度为50℃,最适反应pH值为8.0,在20~30℃和pH值为7.0~8.0时表现出较好的稳定性。结合酶学性质研究结果,确定酶的最适反应条件为30℃,pH值为8.0,并测定了岩藻多糖酶水解反应的动力学参数,K_m为1.17mg/mL,V_max为10.53g·L-1·min-1。该酶降解岩藻多糖的酶活力较高,在岩藻多糖资源的开发领域具有较大应用潜力。     

基于粗略到精细分类的面部表情识别方法

为了更准确地识别人的表情,在识别人脸7种基本表情（愤怒、厌恶、恐惧、高兴、无表情、悲伤和惊讶）时,采用了局域二值模式技术提取面部特征,进行由粗略到精细的表情分类。在粗略分类阶段,7种基本表情中的2种表情被选为初步分类结果（候选表情）。在精细分类阶段,选用计算加权卡方值确定最终分类结果。采用日本的Jaffe表情数据库来验证算法性能,对陌生人表情的识别率为77.9%,其结果优于采用同样数据库的其他方法,且易于实现。     

国产光栅型漫反射式近红外光谱仪实验样机性能及使用方法的研究

使用国产光栅近红外光谱仪实验样机测定玉米籽粒中蛋白质含量,通过与付里叶变换近红外光谱仪测试结果对比结果表明,在（１）规范的测试方法（２）严格的建模条件和优秀的建模软件这两个前提下该仪器可以用于农产品品质分析。     

基于表情相似性的人脸表情流形

在图嵌入(graph embedding)的框架下提出一种根据表情相似度构建邻接权重图的方法来学习人脸表情子空间.数据集中人脸图像的表情以半监督-学习的方式来估计,人脸图像之间的表情相似性由表情模糊隶属度矢量之间的内积来度量,与个体、光照、姿态等人脸差异无关.在得到的子空间内,相似表情的人脸图像位于流形上的邻近位置,表情数据在子空间内按语义的分布很好地揭示了表情模糊、演变的特性.在Cohn-Kanade人脸表情数据库和实验室自行采集的人脸表情数据集上的实验结果说明了该方法的有效性.因此,该方法可以很好地应用于各种基于人脸表情识别的人机交互中.     

基于复杂性K近邻规则的蛋白质亚细胞位点预测

提出了一个基于符号序列LZ复杂性相似度和K近邻规则的蛋白质亚细胞位点类型预测的方法。相比许多其他特征参数,蛋白质序列的LZ复杂性相似度计算无需深入的生物学领域知识和除序列数据以外的其他辅助数据。同时,K近邻规则的延迟学习特性适合于亚细胞位点类型已知的蛋白质数据的动态增加。在标准的RH数据集上对该预测方法进行10重交叉验证,其总体的预测准确率优于4种对照预测方法。     

Brodford法快速测定肌肉蛋白质

本文探讨Ｂｒｏｄｆｏｒｄ法直接、快速测定肌肉蛋白质含量方法。样品分别采用物理和化学法处理，两者无显著差异。标准曲线分别采用ＢＳＡ和凯氏标定肉液进行制作，两者有显著差异，最大吸收波长（λ）５９５ｎｍ，回收率９５～１０２％，显色稳定性６０Ｍｉｎ，灵敏度范围１～２０μｇ。操作简便，无需昂贵仗器，每测一个样品仅需１５～２０Ｍｉｎ。     

Biochemical estimation of hepatitis B surface antigen in recombinant yeast

Purified recombinant hepatitis B surface antigen separated on polyacrylamide gels in the presence of sodium dodecyl sulphate has a very low staining index with Coomassie blue relative to a number of standard proteins. In contrast the protein stains better than average with silver nitrate. This property has been used to develop a semi-quantitative method of estimation of recombinant surface antigen in extracts of Saccharomyces cerevisiae producing this protein. The method can be used to follow purification protocols. It is quick, simple and since it measures the surface antigen biochemically, is independent of the aggregation state or conformation of the protein, a factor which can affect enzyme-linked immunoassays which rely on antigen-antibody interactions.     

Spray Drying of Biopharmaceuticals: Stability and Process Considerations

Spray drying represents an elegant one-step process for producing biopharmaceutical formulations with unique particle characteristics. However, the full potential of spray drying of therapeutic/proteins/peptides has yet to be fully exploited. The reluctance of utilizing spray drying for formulation development may stem from the fact that the process oftentimes subjects the therapeutic actives to temperatures in excess of 100°C, which is a concern for thermally labile drugs as spray drying was performed primarily on co-current spray dryer in a single-stage mode. In this review we discuss the respective dehydration mechanisms of spray drying and the appropriate formulation strategies that can be taken to minimize detrimental effects on biomolecules.     

Peptidoglutaminase deamidation of proteins and protein hydrolysates for improved food use1

The limited deamidating ability of peptidoglutaminase (PGase) toward intact food proteins (0- 6% deamidation) can be significantly enhanced by prior protein hydrolysis and altering protein conformation by such means as moist heat. PGase deamidation increases protein solubility and improves emulsifying and other physical properties under mildly acidic conditions. A batch reactor method was developed for the large- scale PGase deamidation of food proteins. Michaelis- Menten kinetics for industrial reactions (mixed zero- and first- order) were used for predicting the behavior of the reactor and for calculating enzyme dosage required to completely deamidate a given quantity of protein. Using such a reactor in the deamidation of food proteins or protein hydrolysates can lead to new food proteins with superior functional properties from less functional starting materials. ¹Part of a symposium entitled “Preparation and Processing of Chemically-Physically Modified Proteins” held April 25, 1990, Session II at the 81st Annual Meeting of AOCS in Baltimore, MD. *To whom correspondence should be addressed at USDA-ARS-SRRC, P.O. Box 19687, New Orleans, LA 70179. 2Commercial firms are mentioned in this publication solely for the purpose of providing specific information. Mention of a company does not constitute a guarantee or warranty of its products by the U.S. Department of Agriculture nor an endorsement by the Department over products of other companies not mentioned.