Screening of microorganisms producing cold-active oxidoreductases to be applied in enantioselective alcohol oxidation. An Antarctic survey     

Araújo LS  Kagohara E  Garcia TP  Pellizari VH  Andrade LH 《Marine drugs》2011,9(5):889-905

Several microorganisms were isolated from soil/sediment samples of Antarctic Peninsula. The enrichment technique using (RS)-1-(phenyl)ethanol as a carbon source allowed us to isolate 232 psychrophile/psychrotroph microorganisms. We also evaluated the enzyme activity (oxidoreductases) for enantioselective oxidation reactions, by using derivatives of (RS)-1-(phenyl)ethanol as substrates. Among the studied microorganisms, 15 psychrophile/psychrotroph strains contain oxidoreductases that catalyze the (S)-enantiomer oxidation from racemic alcohols to their corresponding ketones. Among the identified microorganisms, Flavobacterium sp. and Arthrobacter sp. showed excellent enzymatic activity. These new bacteria strains were selected for optimization study, in which the (RS)-1-(4-methyl-phenyl)ethanol oxidation was evaluated in several reaction conditions. From these studies, it was observed that Flavobacterium sp. has an excellent enzymatic activity at 10 °C and Arthrobacter sp. at 15 and 25 °C. We have also determined the growth curves of these bacteria, and both strains showed optimum growth at 25 °C, indicating that these bacteria are psychrotroph.  相似文献   

天然羊草草地绵羊采食的季节变化     

陈文青  张英俊 《草业科学》2013,30(2):266-273

饱和链烷技术在国际上已被认为是估测家畜采食组分最为准确的方法，并且随着额外指示剂长链醇和长链酸的引入，进一步完善了该技术，使得对复杂采食组分的估测成为可能。本试验中利用饱和链烷与长链醇或长链酸的适当组合对绵羊在天然羊草（Leymus chinensis）草地的采食组分进行了测定。结果表明，在整个放牧季羊草、苔草(Carex duriuscula)和碱蓬(Suaeda heteroptera)为主要采食组分，但具有明显的季节性差异。6月，碱蓬所占比例最大，其次为羊草和苔草；7月，绵羊对苔草和碱蓬的采食出现大幅下降，而对羊草的采食出现大幅上升；8月，苔草成为最主要的采食组分，对羊草的采食降至放牧季最低，碱蓬的比例明显增加；其他草种如滨藜（Atriplex patens）、蒲公英（Taraxacum mongolicum）、芦苇（Phragmites communis）等为微量组分或采食比例不大。这种采食差异与草地植被的水平和垂直分布密切相关，而且采食植物的适口性在一定程度上也会影响家畜采食。另外，采食比例较大的植物组分，如羊草，择食指数并不高甚至表现为避食，而采食比例较低的植物，如芦苇、滨藜等，择食指数则较高。  相似文献   

醇类沸点影响因素的回归分析     

陈亚  古昆  金振辉 《云南农业大学学报(自然科学版)》2000,15(2):142-145

 利用计算机程序对醇沸点数据进行分析,证实了醇的沸点随着分子碳原子数目、甲基数目、羟基数目的增加而升高。  相似文献   

Cultivar characterization of Aegean olive oils with respect to their volatile compounds     

Huri Ilyasoglu  Beraat Ozcelik  Vera Van Hoed  Roland Verhe 《Scientia Horticulturae》2011

Cultivar characterization of Aegean olive oils (cv. Ayvalik and Memecik) based on their volatile compounds was carried out. The main volatile compounds detected in the Aegean olive oils were the C6 compounds derived from polyunsaturated fatty acids through the lipoxygenase pathway. The C6 aldehydes and C6 alcohols contributing to the green and fruity sensory notes of olive oil were determined in the Aegean olive oils as the major volatile compounds. Significant differences in the levels of hexanal, (E)-2-hexenal, 3-ethyl-1,5-octadiene and total compounds from linolenic acid were observed between Ayvalik and Memecik oils (p < 0.01). Principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to process the experimental data. The results of the chemometric analysis revealed that the two cultivars were clearly discriminated on the PC1–PC3 planes and LDA produced a 100% correct group classification.  相似文献   

紫苏子油不皂化物的分离与分析   总被引：8，自引：0，他引：8  

杨晓静  王立众  李和 《中国油料作物学报》2006,28(2):207-209

采用快速硅胶柱层析和气相色谱对紫苏子油中甾醇、4 - 甲基甾醇及三萜醇等不皂化物的成分进行了分 离和分析。并用气相色谱- 质谱联用技术确定了甾醇中的7种化合物,它们分别为胆甾醇(Cholesterol) 、菜油甾醇 (Campesterol) 、豆甾醇( Stigmasterol) 、β - 谷甾醇(β - Sitosterol) 、α - 菠菜甾醇(α - Sp inasterol) 、Δ5 - 燕麦甾醇(Δ5 - Avenasterol)和Δ7 - 豆甾烯(Δ7 - Stigmastenol) 。  相似文献   

魔芋粉-壳聚糖-聚乙烯醇共混胶黏剂的结构表征   总被引：3，自引：3，他引：0  

顾蓉  穆宝宁  郭康权 《农业工程学报》2013,29(7):277-283

为了拓宽魔芋粉的应用领域,开发环境友好型木材胶黏剂,在前期研究基础上,笔者进一步探讨了胶黏剂的胶合机理和工业化的可行性：通过红外光谱(FTIR)对共混胶的分子间的相互作用以及胶接界面进行了微观结构分析;借助X-射线衍射(XRD)辅助探讨了葡甘聚糖(KGM)、壳聚糖(CA)、聚乙烯醇(PVA)3种纯物质和三元共混胶黏剂的微观结构中官能团的变化;同时利用原子力显微镜(AFM)直观的观察分析胶膜结构,揭示了三元共混胶黏剂的胶合机理;经过成本估算并与市售胶黏剂比较,对其应用于工业生产进行了可行性分析。结果表明：FTIR和XRD分析发现3种高分子之间存在着氢键等强烈的相互作用,并且发现胶黏剂中的活性基团与杨木中的纤维素和半纤维素上的羟基发生了作用,从而得到胶黏剂与界面之间也有强烈作用;AFM分析表明通过PVA的加入,明显改善了以前的双螺旋结构,因此也有效地提高了耐水性能;前景分析表明该胶具有易于形成工业化生产的特点,其制备工艺与白乳胶相似,能够适应白乳胶的生产设备。以上研究结果为探索生物质环保胶黏剂提供了参考。  相似文献   

巴马神酒香气成分的GC—MS分析     

袁竹连  张贞发 《广西农业科学》2013,(5):833-837

【目的】了解巴马神酒的香气特征,为生产品质优良的巴马神酒及其系列产品、鉴别伪劣产品、规范市场营销提供重要参考依据。【方法】以溶液萃取法提取巴马神酒中的香气成分,利用气相色谱一质谱联用技术（Gc．MS）进行分析鉴定。【结果】从巴马神酒中共检测出16种香气化合物,分别为醇类、缩醛类、酚类、酯类、烃类和杂烷类,其中醇类、缩醛类、酚类是巴马神酒中香气贡献最大的三类化合物,占相对质量分数的92．612％;主要的香气化合物有：苯乙醇（44．480％）、十二醛二甲缩醛（18．801％）、3-甲基丁醇（13．212％）、二丁基羟基甲苯（8．679％）、2。甲基丁醇（5．822％）,占相对质量分数的90．994％。【结论】巴马神酒中各香气成分含量存在较大差异,但相互作用共同赋予了巴马神酒独特的香气风格和品质。  相似文献   

玉米淀粉多元醇液化工艺研究     

黄元波  郑云武  郑志锋  周琼  冯昊 《西南林学院学报》2011,31(1):72-74,83

通过单因素实验法,研究了液化剂配比、液化时间、液化温度、催化剂用量、玉米淀粉与液化剂配比对玉米淀粉液化效果和液化产物羟值的影响。结果表明,硫酸是玉米淀粉多元醇液化的有效催化剂;玉米淀粉最佳液化工艺为：玉米淀粉与液化剂质量比为1：6,硫酸用量为液化剂质量的3％,液化剂中PEG400和甘油质量比为7：3,液化时间25min,液化温度150℃,此条件下液化残渣率为2．0％,所制备的玉米淀粉液化产物羟值为447．0mgKOH／g。  相似文献   

3个品种早春绿茶主要香气成分的比较   总被引：1，自引：1，他引：0  

郭建华  张兰兰  边金霖  骆耀平 《福建农林大学学报(自然科学版)》2011,40(6):590-594

采用顶空固相微萃取—气质联用法分析了由乌牛早、鸠坑、福云6号3个茶树品种鲜叶制成绿茶的香气成分,分别鉴定出43、51、42种香气成分.结果表明,3个茶样的香气成分主要以醇类化合物为主,其次为萜烯类和烷烃类化合物,而醛类、酮类和酯类化合物总量较低,未检测到酸类化合物.乌牛早的醇类化合物(57.6％)显著高于鸠坑(35.2...  相似文献   

Digestibility of Calanus finmarchicus wax esters in Atlantic salmon (Salmo salar) freshwater presmolts and seawater postsmolts maintained at constant water temperature     

A. OXLEY  A.S. BOGEVIK  R.J. HENDERSON  R. WAAGBø  D.R. TOCHER  & R.E. OLSEN 《Aquaculture Nutrition》2009,15(5):459-469

Calanoid copepods are a rich source of marine lipid for potential use in aquafeeds. Copepod oil is primarily composed of wax esters (WE) and there are concerns over the efficiency of wax ester, versus triacylglycerol (TAG), digestion and utilization in fish. As smoltification represents a period of major physiological adaptation, the present study examined the digestibility of a high WE diet ( Calanus oil; 48% WE, 26% TAG), compared with a TAG diet (fish oil; 58% TAG), in Atlantic salmon freshwater presmolts and seawater postsmolts, of similar age (9 months) and weight (112 g and 141 g initial, respectively), over a 98-day period at constant temperature. Fish grew significantly better, and possessed lower feed conversion ratios (FCR), in seawater than freshwater. However, total lipid apparent digestibility coefficient (ADC) values were significantly lower in seawater fish, as were total fasted bile volumes. Dietary Calanus oil also had a significant effect, reducing growth and lipid ADC values in both freshwater and seawater groups. Postsmolts fed dietary Calanus oil had the poorest lipid ADC values and analysis of faecal lipid class composition revealed that 33% of the remaining lipid was WE and 32% fatty alcohols. Dietary prevalent 22:1n-11 and 20:1n-9 fatty alcohols were particularly poorly utilized. A decrease in primary bile acid, taurocholate, concentration was observed in the bile of dietary Calanus oil groups which could be related to the lower cholesterol content of the diet. The dietary WE : TAG ratio is discussed in relation to life stage and biliary intestinal adaptation to the seawater environment postsmoltification.  相似文献