Enantio-selective preparation of (S)-1-phenylethanol by a novel marine GDSL lipase MT6 with reverse stereo-selectivity

We previously functionally characterized a novel marine microbial GDSL lipase MT6 and identified that the stereo-selectivity of MT6 was opposite to that of other common lipases in trans-esterification reactions.Herein,we have investigated the use of MT6 in stereo-selective biocatalysis through direct hydrolysis reactions.Notably,the stereo-selectivity of MT6 was also demonstrated to be opposite to that of other common lipases in hydrolysis reactions.Parameters,including temperature,organic co-solvents,pH,ionic strength,catalyst loading,substrate concentration,and reaction time,affecting the enzymatic resolution of racemic 1-phenylethyl acetate were further investigated,with the e.e.of the final（S）-l-Phenylethanol product and the conversion being 97%and 28.5%,respectively,after process optimization.The lengths of side chains of 1-phenylethyl esters greatly affected the stereo-selectivity and conversion during kinetic resolutions.MT6 is a novel marine microbial GDSL lipase exhibiting opposite stereo-selectivities than other common lipases in both trans-esterification reactions and hydrolysis reactions.

β-苯乙醇制备工艺研究

为进一步探究β-苯乙醇制备工艺的可能优化路径,本文参考相关研究资料和实际情况,以环氧苯乙烷加氢方法制备β-苯乙醇,并通过多组平行实验,确定最优实验组合为:环氧苯乙烷用量为2.0 g,催化剂用量为0.04 g,溶剂用量为15 g,反应时间为1.5 h,反应温度为25℃。而后基于该实验组合进行放大实验与分析表征,结果显示,本次实验在产率上相对较优,且副产物较少,具有一定的实际应用价值。

Lipase immobilized on HOOC-MCF:A highly enantioselective catalyst for transesterification resolution of (R,S)-1-phenylethanol

Pseudomonas cepacia lipase （PSL） immobilized on the carboxyl-functionalized meso-cellular foams （HOOC-MCF） was used for the transesterification resolution of （R,S）-l-phenylethanol in organic solvent. The results showed that the ee value of （S）-1- phenylethanol and （R）-1-phenylethyl acetate reached 99% with 50% conversion of 1-phenylethanol using toluene as solvent. Furthermore, it was found that PSL/HOOC-MCF exhibited high enantioselectivity in organic solvent with log P ≤ 2 such as toluene and hexane.

Growth inhibition and oxidative stress in two species of marine diatoms exposed to 1-phenylethanol

1-phenylethanol (1-PEA) is a flavor extensively used in the production of cosmetics, beverages, and food. The release of 1-PEA into coastal environments has aroused great concern. However, its potential effects on marine organisms are still unknown. In order to provide a better understanding of the ecological risks of 1-PEA in marine environments, this study determined the toxic effects of 1-PEA on two marine diatoms (Phaeodactylum tricornutum and Skeletonema costatum). The diatoms were grown in culture medium containing different concentrations of 1-PEA for 96 h. The contents of chlorophyll a, chlorophyll c, glutathione (GSH), malondialdehyde (MDA), and the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), were measured at the end of the exposure period. 1-PEA was shown to significantly inhibit the growth of diatoms, with 96-h EC50 values of 257.14 mg/Land 126.46 mg/L in P. tricornutum and S. costatum, respectively. In P. tricornutum, the levels of SOD, CAT, GPx, GSH, and MDA were stimulated only when 1-PEA concentrations were close to or greater than the 96-h EC50 value. However, in S. costatum, the activities of SOD and CAT, and the syntheses of two chlorophylls were inhibited even at an exposure concentration below the 96-h EC50 value. Taken together, these findings indicate a potential ecological risk by discharging 1-PEA into coastal areas and its species-specific toxic effects on marine organisms.

Relationship between Ethanol and 2-phenylethanol Stress Tolerance and Fatty Acid Compositions of Saccharomyces cerevisiae

In the present study, we investigated of the ethanol （Eth）, 2-phenylethanol （2-PE） and ethanol/2-phenylethanol （Eth/2-PE） stress tolerance and established relationship between stress tolerance and fatty acid compositions of wine yeast strain S. cerevisiae UCM Y-524 in relation to different cultivation factors. Changes in cell membrane fatty acid profiles studied under different temperature and media. The active oxygenation, semi-aerobic cultivation supplemented Tween 80 conditions were used in different combinations. The concentrations of 2-PE and Eth, the fatty acids methyl esters （FAMES） in the media were measured by GC-MS analyses. 2-PE, Eth, FAMES were identified by NIST02 MS database at the 2-PE and Eth standard solution （Merck, Germany）, bacterial FAMES standard （Supelco）. Palmitoleic and oleic acid were dominated for S. cerevisiae UCM Y-524. The unsaturated/saturated fatty acid （UFA/SFA） ratio was higher than five for S. cerevisiae UCM Y-524 at 14 ~C in simple medium and about more than three for other conditions. It has been found that yeast cells grown in the presence of the 2-PE, Eth and Eth/2-PE appear to increase the amount of unsaturated fatty acids, especially oleic acid, in cellular lipids especially under active oxygenation supplemented with Tween 80. S. cerevisiae UCM Y-524 has a higher tolerance under 2-PE, Eth and Eth/2-PE stress at 28 ~C in a simple medium under aerobic conditions. A higher concentration of unsaturated fatty acids in the membrane S. cerevisiae UCM Y-524 and a lower temperature under aerobic conditions, has been considered to have a positive influence on the excretion of 2-phenylethanol.

天然酱醪中产β-苯乙醇酵母菌的分离鉴定、发酵条件优化及其应用

为了提升酱油品质,开展筛选产β-苯乙醇的酵母菌,并应用在高盐稀态发酵酱油酿造的研究。从天然酱醪中筛选出产β-苯乙醇的酵母菌株J13,对其进行形态学观察、生理生化实验及分子生物学鉴定,通过耐盐性、pH耐受性及温度耐受性分析研究Z.rouxii 13的生物学特性,并采用单因素和正交试验对培养基成分及发酵条件进行优化,在最优发酵条件下培养Z.rouxii 13,获得风味液并应用到高盐稀态发酵酱油的酿造工艺中。结果表明,J13鉴定为鲁氏接合酵母(Zygosaccharomyces rouxii),并命名为Z.rouxii 13,能在含盐量较高(18%NaCl)条件下生长,最适pH为4~8及最适温度为20~35℃,其产β-苯乙醇的最优发酵条件为:L-苯丙氨酸4 g/L、葡萄糖30 g/L、蛋白胨10 g/L、硫酸镁0.5 g/L、磷酸氢二钾5 g/L、NaCl 50 g/L、pH6.0,温度28℃,在此条件下β-苯乙醇含量达到1.40 g/L。该风味液用于酱油酿造获得成品的感官评定结果表明,相比不添加风味液的空白对照组,风味液组的酱香和醇厚感更突出,鲜味及整体评价更佳。

傅克烷基化法制备β-苯乙醇的工艺研究

通过傅克烷基化法制备标题化合物,通过单因素和正交试验,考察了反应物物质的量比、反应温度、反应时间等对收率的影响,最终确定合成标题化合物的最优条件为:n(苯)∶n(三氯化铝)∶n(环氧乙烷)=2.4∶0.3∶0.2,加料采用滴加方式[滴加混合液中m(苯)∶m(环氧乙烷)=12∶1],滴加温度6~9℃,反应温度6~12℃,反应时间80 min。对β-苯乙醇粗产品一次蒸馏含量可达98.31%。该方法成本低,工艺流程简单,适合中小企业规模化生产。

我国黄酒酵母和酿酒原料对黄酒中β-苯乙醇含量的影响

采用新建立的液-液微萃取-气相色谱法快速测定发酵液中β-苯乙醇含量,比较了不同酵母菌种及不同原料对黄酒酿造过程中β-苯乙醇生成的影响。研究结果表明,浙江地区黄酒酵母的β-苯乙醇合成能力要明显高于上海地区黄酒酵母菌;不同酿酒原料对β-苯乙醇的产生也有较大影响,高粱玉米等非稻米原料发酵生成β-苯乙醇的含量要高于稻米原料,β-苯乙醇产量与原料中苯丙氨酸含量呈正相关性。

β-苯乙醇的研究进展

β-苯乙醇是一种有广泛用途的香味物质,在食品、化妆品、烟草和日化用品中添加β-苯乙醇对其他香气成分有增效作用。该文综述了β-苯乙醇来源,提取与检测,生产方法,并对β-苯乙醇的代谢机理及未来研究进行了展望。

反相高效液相色谱法测定黄酒中的β-苯乙醇

建立一种采用反相高效液相色谱法测定黄酒中β-苯乙醇的方法。采用反相C18色谱柱SynergiHrdro-RPC18(4.6mm×250mm,4μm),以甲醇-水为流动相(50:50,V/V),流速1ml/min,紫外检测器,检测波长210nm,对黄酒中的β-苯乙醇进行检测。结果表明,在5.00～30.00mg/L添加量范围内,回收率水平在99.5%～99.8%之间,相对标准偏差为0.6%(n=6),方法的检出限为0.05mg/L,线性范围为0.5～50mg/L(r=0.9999),测定结果与标准气相色谱方法基本相同。所建立的方法可以作为黄酒中β-苯乙醇的检测方法。

气相色谱法测定黄酒中β-苯乙醇的含量

研究了以毛细管气相色谱法测定黄酒中β-苯乙醇的方法。用正己烷萃取黄酒样品中的β-苯乙醇,经旋转蒸发仪浓缩,采用TR-WAX(30 m×0.32 mm i.d×0.25μm)气相色谱柱分离,氢火焰离子化检测器检测,并以保留时间定性和峰面积定量。方法的线性范围为0.5mg/L^50mg/L(r=0.9993),检测限0.2mg/L,相对标准偏差为1.02%(n=5),回收率为92.2%~105.9%(n=5)。

酿酒酵母AS 2.1182发酵产β-苯乙醇的研究

以1株酿酒酵母AS2.1182生物转化生产天然香料β-苯乙醇,通过摇瓶发酵对相关单因素条件进行试验,针对影响产β-苯乙醇的主要因素,再采用MINITAB软件,Box-Behnken实验设计及响应面分析进行工艺条件优化,优化的培养条件为:葡萄糖29.62g/L、L-苯丙氨酸8g/L,KH2PO40.5g/L,MgSO40.5g/L,豆粕粉加入量6.18g/L,接种量4.33%,在28℃,转速200r/min条件下发酵90h后,采用HPLC分析β-苯乙醇含量可以达到3.26g/L,相对优化前提高了14.38%。分析等高线图得出,豆粕粉加入量与接种量、豆粕粉加入量与葡萄糖浓度的交互作用显著,而葡萄糖浓度与接种量的交互作用不显著。

生物转化法生产β苯乙醇

β-苯乙醇是一种多功能的精细化学品,在食品、日化和轻工等领域有着广泛的应用,全球每年近万吨的β苯乙醇产品基本都是采用化学方法合成,随着人们对天然添加剂的日益需求,迫切需要开发其可以替代的新型生产技术,生物转化法是获得天然β-苯乙醇的最佳途径。概述了生物转化法生产β-苯乙醇的方法,着重介绍β苯乙醇合成的代谢途径、转化的微生物种类和β苯乙醇对酵母细胞毒性问题。

气相色谱-质谱法测定豉香型白酒中β-苯乙醇及3种二元羧酸的二乙酯

用2-乙基正丁酸为内标物,提出用气相色谱-质谱联用全扫描法测定豉香型白酒中β-苯乙醇和在特定保留时间窗内选择性离子法测定庚二酸二乙酯、辛二酸二乙酯和壬二酸二乙酯含量。此方法对β-苯乙醇的检出限(S/N=3)为5.0mg·L^(-1),对其他3种二元羧酸的二乙酯的检出限均为0.01mg·L^(-1),测得方法的回收率在90%～110%之间,相对标准偏差(n=10)均小于9%。

黄酒β-苯乙醇含量的近红外光谱快速检测

利用近红外光谱技术对黄酒主要香气指标β-苯乙醇进行了快速检测,采集了不同品牌和酒龄的112份黄酒样品,以气相色谱所测β-苯乙醇含量为参考值,在800~2 500 nm波段范围内建立了回归分析模型。结果显示,SNV预处理结合偏最小二乘回归法在全波段范围内所建立的模型性能最优,校正模型的相关系数rc为0.949,RMSEC为6.66 mg/L,RMSEP为10.4 mg/L,相对标准偏差RPD达到1.83。结果表明应用近红外光谱技术对黄酒β-苯乙醇含量进行快速检测筛分是可行的。下一步研究拟加大样本量来提升模型的精度和稳健性。

民族药珠芽艾麻化学成分研究

目的:对荨麻科艾麻属珠芽艾麻药材进行化学成分研究。方法:经70%乙醇回流提取,通过硅胶柱层析等技术,进行分离纯化,结合理化性质及各种波谱数据分析鉴定其化学结构。结果:从珠芽艾麻的根中分离并鉴定了6个化合物,分别是:β-谷甾醇(1)、β-胡萝卜苷(2)2、2,'-oxy-bis(1-phenylethanol)(3)、1-(2-phenylcarbonyloxy ac-etyl)benzene(4)、亚油酸甲酯(5)和14,-二苯基-14,-丁二酮(6)。结论:所有化合物均为首次从该植物中分离得到,其中化合物3和4为首次报道的天然产物。

金属氯化物对硼氢化钠还原α-氯代苯乙酮的影响

用NaBH4还原α-氯代苯乙酮制备相应的β-氯代-α-苯乙醇时,在较高的反应温度下产生许多副产物,钙、镧、镁、锰、锌等金属氯化物的存在能有效抑制副反应的发生,高产率地得到产物.

β-苯乙醇合成工艺的研究

以苯和环氧乙烷为原料,在催化剂SnCl4的作用下,通过Friedel-Crafts反应制得β-苯乙醇,采用单因素试验法,通过考察影响收率的主要因素,确定出最佳工艺条件:物料配比为1.0:0.25、催化剂用量为0.3 mol、反应时间为40 min、反应温度为6～9℃,总收率可达51.6%.

微生物转化法生产β-苯乙醇的研究进展

β-苯乙醇是具有玫瑰风味的芳香醇,玫瑰芬芳的广泛需求使得β-苯乙醇成为香料和化妆品中使用最多的香味成份。利用微生物生产β-苯乙醇的原理即为利用酶或微生物将前体物L-苯丙氨酸转化为β-苯乙醇。概述了生物转化法生产β-苯乙醇的方法,介绍了β-苯乙醇合成的代谢途径、转化的微生物种类、β-苯乙醇对酵母细胞毒性和发酵液中β-苯乙醇提取。