氯化三辛基甲胺/氯仿/正丁醇反胶束萃取地木耳多糖

采用阳离子表面活性剂氯化三辛基甲胺(TOMAC)/氯仿/正丁醇反胶束体系萃取地木耳中的多糖。分析有机溶剂氯仿与助表面活性剂正丁醇比例、TOMAC浓度、多糖粗提液浓度、促溶剂盐酸胍浓度、盐离子种类和浓度对前萃取率的影响。结果表明:向0.5 mg/m L多糖粗提液中加入10 mmol/L盐酸胍(Gu HCl)和0.06 mol/L Na Cl,与等体积25 mmol/L TOMAC/氯仿-正丁醇(V∶V=3∶1)的反胶束体系混合,地木耳多糖前萃取率为53.21%;反萃时水相中Na Cl浓度为0.14 mol/L,盐酸胍浓度浓度为0.6 mol/L,在此条件下地木耳多糖反萃取率为93.2%。     

萃取耦合技术对玉米秸秆水解液发酵产丁醇的影响

本研究以玉米秸秆水解液为原料,通过萃取发酵技术生产燃料丁醇,以提高丁醇产量,降低生产成本。通过对萃取剂的筛选与条件优化,确定纤维丁醇发酵的萃取剂为油醇,添加时间为发酵0 h,添加比例为1:1 (V/V)。该条件下发酵32 g/L糖浓度的玉米秸秆水解液,丁醇和总溶剂产量分别为3.28 g/L和4.72 g/L,比对照分别提高958.1%和742.9%。以D301树脂脱毒后5%总糖浓度的玉米秸秆水解液进行丁醇萃取发酵,丁醇和总溶剂产量分别达到10.34 g/L和14.72 g/L,发酵得率为0.31 g/g,与混合糖发酵结果相当。研究结果表明萃取发酵技术能够显著提高原料的利用率和丁醇产量,为纤维丁醇工业化生产提供了技术支撑。     

萃取耦合发酵工艺生产丁醇研究

萃取耦合发酵可有效减弱产物抑制和提高底物利用效率,本文就萃取耦合发酵生产丁醇工艺中的萃取剂的选择、萃取剂加入量、底物浓度等发酵条件进行了研究。结果表明:最佳萃取剂为大豆油生物柴油,油水比为3∶5,发酵过程无需搅拌,静置发酵为宜,在发酵之初加入萃取剂。分别以玉米和木薯为发酵底物,确定其最适底物浓度为100 g/L,以玉米为原料萃取耦合发酵中丁醇和总溶剂产量分别为18.17 g/L和29.31 g/L。以木薯为原料萃取耦合发酵生产丁醇及总溶剂产量比传统发酵分别提高了48.69%和51.80%。     

嗜热子囊菌利用短链有机酸生产角质酶

以嗜热子囊菌(Thermobifida fusca WSH03-11)发酵生产角质酶为模型,研究微生物利用市政污泥厌氧酸化所产短链有机酸为碳源发酵生产高附加值产品的可能。发现：(1)以丁酸、丙酸和乙酸为碳源时,有机酸和氮元素浓度分别为8.0 g/L和1.5 g/L有利于角质酶的生产;而以乳酸为碳源时,最适有机酸和氮源浓度分别为3.0 g/L和1.0 g/L;(2)改变诱导物角质的浓度,以丁酸、丙酸、乙酸和乳酸为碳源,分别比优化前提高了31.0%、13.3%、43.8%和73.2%;(3)在四种有机酸中,T. fusca WSH03-11利用乙酸的速率最快,平均比消耗速率是丙酸的1.3倍,丁酸的2.0倍及乳酸的2.2倍;以丁酸为碳源时的酶活(52.4 U/mL)是乳酸的1.7倍、乙酸的2.5倍和丙酸的3.2倍;角质酶对乳酸的得率(12.70 u/mg)分别是丁酸的1.4倍、丙酸的3.0倍和乙酸的3.8倍;(4)以混合酸为碳源生产角质酶,T. fusca WSH03-11优先利用乙酸,而对丁酸的利用受到抑制。进一步研究发现,混合酸中0.5 g/L的乙酸将导致丁酸的消耗量降低66.7%。这是首次利用混合酸作碳源发酵生产角质酶的研究报道。这一研究结果进一步确证了利用市政污泥厌氧酸化所产有机酸为碳源发酵生产高附加值产品的可行性,为以廉价碳源生产角质酶奠定了良好的基础。     

嗜热子囊菌利用短链有机酸生产角质酶

以嗜热子囊菌(Thermobifida fusca WSH03-11)发酵生产角质酶为模型,研究微生物利用市政污泥厌氧酸化所产短链有机酸为碳源发酵生产高附加值产品的可能。发现：(1)以丁酸、丙酸和乙酸为碳源时,有机酸和氮元素浓度分别为8.0 g/L和1.5 g/L有利于角质酶的生产;而以乳酸为碳源时,最适有机酸和氮源浓度分别为3.0 g/L和1.0 g/L;(2)改变诱导物角质的浓度,以丁酸、丙酸、乙酸和乳酸为碳源,分别比优化前提高了31.0%、13.3%、43.8%和73.2%;(3)在四种有机酸中,T. fusca WSH03-11利用乙酸的速率最快,平均比消耗速率是丙酸的1.3倍,丁酸的2.0倍及乳酸的2.2倍;以丁酸为碳源时的酶活(52.4 U/mL)是乳酸的1.7倍、乙酸的2.5倍和丙酸的3.2倍;角质酶对乳酸的得率(12.70 u/mg)分别是丁酸的1.4倍、丙酸的3.0倍和乙酸的3.8倍;(4)以混合酸为碳源生产角质酶,T. fusca WSH03-11优先利用乙酸,而对丁酸的利用受到抑制。进一步研究发现,混合酸中0.5 g/L的乙酸将导致丁酸的消耗量降低66.7%。这是首次利用混合酸作碳源发酵生产角质酶的研究报道。这一研究结果进一步确证了利用市政污泥厌氧酸化所产有机酸为碳源发酵生产高附加值产品的可行性,为以廉价碳源生产角质酶奠定了良好的基础。     

樟芝挥发油的微波辅助双液相萃取及其抗菌活性研究

采用微波辅助石油醚/乙醇双液相萃取技术提取樟芝发酵液中的挥发油,并考察了其对7种皮肤癣菌的最低抑制浓度(MIC)。优化的提取条件为:乙醇体积浓度56%,石油醚体积浓度30%,固液比1∶50,微波功率380 W,微波时间90 s。此时,挥发油的提取率为0.69%,真菌MIC为5-20 m L/L。微波辅助双液相萃取挥发油耗时短,提取率高,且获得的挥发油抗皮肤癣菌效果显著。     

樟芝挥发油的微波辅助双液相萃取及其抗菌活性研究北大核心CSCD

采用微波辅助石油醚/乙醇双液相萃取技术提取樟芝发酵液中的挥发油,并考察了其对7种皮肤癣菌的最低抑制浓度(MIC)。优化的提取条件为:乙醇体积浓度56%,石油醚体积浓度30%,固液比1∶50,微波功率380 W,微波时间90 s。此时,挥发油的提取率为0.69%,真菌MIC为5-20 m L/L。微波辅助双液相萃取挥发油耗时短,提取率高,且获得的挥发油抗皮肤癣菌效果显著。     

胡芦巴超临界CO2萃取物的萃取条件优化及其对谷蠹的触杀活性

对胡芦巴Trigonella foenum-graecum L.中杀虫活性成分进行超临界CO₂萃取分离,并以主要储粮害虫谷蠹Rhyzopertha dominica Fabricius为对象,对其触杀活性进行研究。采用正交试验设计,以萃取液中活性成分的得率、毒力为考察指标,对杀虫活性成分的提取条件进行优化。结果表明：最佳萃取工艺为萃取压力25 MPa,萃取温度55℃,夹带剂为95%乙醇,固液比为200 g:30 mL。萃取压力和夹带剂体积对试验指标有非常显著的影响,萃取温度和夹带剂浓度的影响较小。优化后的萃取方案可达到5.96%的得率。萃取产物对谷蠹的触杀试验结果显示,优化后的超临界CO₂萃取工艺对胡芦巴中的杀虫物质具有良好的选择性,得到的萃取物对谷蠹处理10天后的致死中浓度为65.03 μg/cm²,触杀活性明显增加。     

一种测定女贞子中齐墩果酸和熊果酸的新方法

为建立一种加速溶剂萃取-毛细管区带电泳测定女贞子中齐墩果酸和熊果酸的新方法.考察了萃取温度、萃取时间和萃取次数对目标物萃取效率的影响,并考察了硼砂浓度,β-环糊精浓度、pH及甲醇浓度对目标物分离的影响.结果表明:(1)萃取温度和萃取次数影响目标物的萃取效率,而萃取时间的影响很小;萃取压力影响萃取过程的重现性.(2)优化的萃取条件为:萃取压力6.9 MPa,萃取温度100℃,萃取时间5 min和萃取次数2次.(3)优化的缓冲体系为:40 mmol/L硼砂,1 mmol/Lβ-环糊精,pH 9.5及6%甲醇.(4)齐墩果酸和熊果酸分别在10~200、10~160 mg/L范围内线性良好,相关系数均大于0.996,检测限分别为3.2 mg/L和3.0 mg/L,加标回收率为93%~97%.对比了加速溶剂萃取、索氏提取以及超声提取的提取效率.(5)不同提取方法比较结果表明,加速溶剂萃取的提取效率与索氏提取法接近,但高于超声提取;加速溶剂萃取法的主要优点是消耗提取溶剂量少,提取时间短,样品用量小.     

龙柏枝叶水浸提液及其萃取物除草活性的生物测定

采用培养皿滤纸法,以油菜(Brassica campestris L. )、反枝苋(Amaranthus retroflexus L. )、生菜(Lactuca sativa L. var. ramosa Hort. )、番茄(Lycopersicon esculentum Miller)和小麦(Triticum aestivum L. )为供试植物,对龙柏(Sabina chinensis 'Kaizuca')枝叶水浸提液的除草活性进行了生物测定,并以番茄为测定对象,对水浸提液的不同溶剂萃取物的除草活性也进行了生物测定;另外,采用薄层层析法对乙酸乙酯萃取物的除草活性成分进行了初步定性分析.结果显示,在0.05～0.2 g·mL-1质量浓度范围内,龙柏枝叶水浸提液对5种植物的种子萌发及幼苗根长和茎高均有一定的抑制作用,且随质量浓度的提高,抑制作用逐渐增强,其中0.2 g·mL-1水浸提液对5种植物的种子萌发及幼苗根长和茎高的抑制率均在80.00%以上, 对番茄种子萌发及幼苗根长和茎高的抑制率最高, 均达到100.00%.在龙柏枝叶水浸提液的石油醚、乙酸乙酯和水萃取物中,0.01、0.02和0.04 g·mL-1石油醚或乙酸乙酯萃取物以及0.02和0.04 g·mL-1水萃取物对番茄种子萌发及幼苗根长和茎高均有一定的抑制作用,且随质量浓度的降低,抑制率逐渐降低;其中,乙酸乙酯萃取物的抑制作用最强,水萃取物的抑制作用最低.薄层层析显色结果表明,龙柏枝叶水浸提液乙酸乙酯萃取物的主要除草活性成分为酚类成分.     

Rapid screening of solvents and carrier compounds for lactic acid recovery by emulsion liquid extraction and toxicity on Lactobacillus casei (ATCC 11443)

This paper describes a rapid method to identify the best solvent and carrier compound combinations with the highest extraction capability and the lowest microbial toxicity characteristics for product recovery from microbial fermentation. The extraction system has an aqueous phase, and an emulsion phase, which was a blend of sodium carbonate and organic phase [91% (v/v) organic solvent, 5% (v/v or wt/v) carrier compound, and 4% (v/v) surfactant Span 80]. Alamine 336, or tri-n-octylamine in n-heptane; Alamine 336, Alamine 304, or tributyl phosphate in hexane; and Alamine 304 or tributyl phosphate in iso-octane; Alamine 304 or Amberlite in xylene demonstrated high lactic acid extraction. For determination of bacterial toxicity of selected solvent and carrier compounds, Lactobacillus casei subsp. rhamnosus (ATCC 11443) was grown in LAF medium containing one of the selected organic solvent, carrier compound, and Span 80 in 250 ml flask at 37 °C and 125 rpm. Samples were collected regularly during 48 hour incubation, and measured for changes in cell density by absorbance at 620 nm, cell count using a fluorescent dye with flow cytometry, and lactic acid, and glucose concentrations by HPLC. Hexadecane:tributyl phosphate, n-dodecane:tri-n-octylamine, and kerosene:tri-n-octylphosphine oxide demonstrated the least microbial toxicity among the tested blends with excess solvent media. Whereas, hexanes:Alamine 304 and xylenes:Alamine 304 were nontoxic in solvent saturated media.This revised version was published online in October 2005 with corrections to the Cover Date.     

罗勒籽脂肪酸及其对蛋白酪氨酸磷酸酯酶1B(PTP1B)抑制作用的研究

利用索氏提取法提取罗勒籽油,向罗勒籽油加入氢氧化钾甲醇溶液后并用水浴加热,加入正已烷和蒸馏水萃取,上清液即为罗勒籽油中脂肪酸,用气相色谱质谱法(CC/MS)对脂肪酸进行鉴定.共鉴定出了4种脂肪酸,其中α-亚麻酸为62.88％、亚油酸为20.66％、棕榈酸为10.67％、硬脂酸为5.79％.对罗勒籽脂肪酸进行PTP1B的抑制作用研究,结果表明脂肪酸对PTP1B有较强的抑制作用,其IC50为11.12 μg/mL.该研究为深入研究罗勒籽的药理作用提供了科学依据.     

Recovery of penicillin by reactive extraction in centrifugal extractors

Penicillin V and/or G were extracted from fermentation broth by Amberlite LA-2 in n-butylacetate at pH 5 in a laboratory centrifugal extractor, Type SA 01 of Westfalia, up to an overall phase throughput rate of 30 L/h, in a bench-scale four-stage extraction system, consisting of Type TA 1 of Westfalia, up to an overall phase throughput rate of 110 L/h, and in a pilot-plant three-stage extraction unit, consisting of Type TA 7 extractors of Westfalia, up to a phase throughput rate of 990 L/h with very high degrees of extraction (up to 99%). The reextraction from the ion-pair complex, which contained organic solvent, was performed by phosphate, borate, or carbonate buffer at pH 7.5-8.5 in all three extractor systems with degrees of extraction up to 98%, but at considerably lower overall phase throughput rates than those of the extraction, since no satisfactory phase separation is possible at higher throughput rates.     

Relations between extraction protocols for activated sludge extracellular polymeric substances (EPS) and complexation properties of Pb and Cd with EPS: Part II. Consequences of EPS extraction methods on Pb2+ and Cd2+ complexation

To study the effect of extraction protocols on extracellular polymeric substances (EPS) metal binding ability, EPS from two activated sludges were extracted by eight extraction protocols: three chemical treatments, four physical treatments and a control. Two pK_a, for each EPS, were determined: pK_a1 may be specific for carboxyl and phosphoric and pK_a2 may be attributed to phenolic and amino functional groups according to EPS composition and IR spectra. EPS pK_a values could be affected by the presence of extraction reagents and/or the modifications of EPS by extraction reagents.Complexation study performed at pH 7 by a polarographic method has always showed a greater affinity of EPS for Pb²⁺ than for Cd²⁺. The complexation properties of EPS extracted by chemical methods were greatly modified. Concerning EPS extracted by physical methods, their complexation properties were close except for EPS obtained by heating. Standardized extraction methods must be established as a function of the aims of the EPS study.     

Effects of aluminium treatment on Norway spruce roots: Aluminium binding forms,element distribution,and release of organic substances

In order to investigate if Al resistance in Norway spruce (Picea abies[L.] Karst.) can be attributed to similar exclusion mechanisms as they occur in several crop plants, three-year-old Norway spruce plants were treated for one week in hydroculture with either 500 μM AlCl₃ or CaCl₂ solutions at pH 4. Sequential root extraction with 1 M NH₄Cl and 0.01 M HCl and EDX microanalysis revealed that Al and Ca in cell walls and on the surface participated in exchange processes. About half of the Al extracted by the sequential extraction was not exchangeable by 1 M NH₄Cl. Phenolics and phosphate present in the root extracts are possible ligands for Al adsorbed to or precipitated at the root in a non-exchangeable form. In both treatments, C release during the first period of 2 d was much higher than during the remaining time of the experiment. Al treated plants released less total C, carbohydrates and phenolics than did Ca treated plants. Acetate was the only organic acid anion that could be detected in some samples of both treatments. Free amino acids were present at micromolar concentrations but as hydrolysis did not increase their yield, there was no evidence of peptide release. One to two thirds of the released C were large enough not to pass a 1 kDa ultrafilter. The results suggest that exudation of soluble organic complexors is not a major Al tolerance mechanism in Norway spruce, although complexation of Al by phenolic substances released by the root could be detected by fluorescence spectroscopy. Aluminium tolerance could rather be attributed to immobilization in the root apoplast, where strong binding sites are available or precipitation may occur. This revised version was published online in June 2006 with corrections to the Cover Date.     

Risk Assessment and Class-Based Evaluation of Three Phosphate Esters

A category approach was used in the evaluation of a group of chemicals (triethyl phosphate, tripropyl phosphate, and tributyl phosphate) in drinking water, in support of determination of safe-harbor level for use by a standard-setting organization. Both non-cancer and cancer endpoints were considered, and risk assessment methodology developed by the U.S. Environmental Protection Agency (USEPA) was used to determine a class-based evaluation level (CBEL) and a total allowable concentration (TAC) in drinking water considered adequately protective of human health. The critical study was a chronic oncogenicity study on tributyl phosphate, with a no-observed-adverse-effect-level (NOAEL) of 9 mg/kg-day. The critical effect, combined incidence of bladder papilloma/transitional cell carcinoma, was likely non-genetic in nature, as supported by the lack of genetic toxicity observed in tributyl phosphate. The effect thus demonstrated a threshold, and this study used an oral reference dose approach and a total uncertainty factor of 100. This conservative analysis demonstrated the TAC should be twenty times greater than the default value of 0.01 mg/L.     

Predicting arsenic bioavailability to hyperaccumulator Pteris vittata in arsenic-contaminated soils

Using chemical extraction to evaluate plant arsenic availability in contaminated soils is important to estimate the time frame for site cleanup during phytoremediation. It is also of great value to assess As mobility in soil and its risk in environmental contamination. In this study, four conventional chemical extraction methods (water, ammonium sulfate, ammonium phosphate, and Mehlich III) and a new root-exudate based method were used to evaluate As extractability and to correlate it with As accumulation in P. vittata growing in five As-contaminated soils under greenhouse condition. The relationship between different soil properties, and As extractability and plant As accumulation was also investigated. Arsenic extractability was 4.6%, 7.0%, 18%, 21%, and 46% for water, ammonium sulfate, organic acids, ammonium phosphate, and Mehlich III, respectively. Root exudate (organic acids) solution was suitable for assessing As bioavailability (81%) in the soils while Mehlich III (31%) overestimated the amount of As taken up by plants. Soil organic matter, P and Mg concentrations were positively correlated to plant As accumulation whereas Ca concentration was negatively correlated. Further investigation is needed on the effect of Ca and Mg on As uptake by P. vittata. Moreover, additional As contaminated soils with different properties should be tested.     

Extraction of nucleic acids from lyophilized plant material

Four methods for extracting nucleic acids from lyophilized cotton (Gossypium hirsutum L. cv. Stoneville 62) leaves and roots were compared. They were based on the use of: (I) HC10₄; (II) KOH; (III) a mixture of 90% phenol, Tris (hydroxymethyl) aminomethane buffer, and sodium lauryl sulfate; and (IV) NaCl. (I) extracted large amounts of RNA but little DNA and extracted much carbohydrate and protein contaminants. (II) gave a good yield of both RNA and DNA but extracted such large amounts of contaminating material that purification of RNA on an anion exchange column was necessary. (III) extracted only part of the RNA and practically no DNA, but extracted contaminating materials. (IV) resulted in high yields of both RNA and DNA when modified to omit preliminary acid extraction of impurities. The use of cold trichloroacetic acid instead of ethanol, to precipitate NaCl-extracted nucleic acids, separated the nucleic acids from most of the carbohydrate and acid-soluble phosphate contaminants and resulted in good agreement among results by ultraviolet absorbance, pentose tests, and phosphate analysis. This method also resulted in lower protein contents and better ultraviolet absorption spectra than the other methods tested. Nucleic acids were extracted from leaves of 14 other species of plants, in addition to cotton, by this modified NaCl procedure.     

Organic acid exudation and pH changes by Gordonia sp. and Pseudomonas fluorescens grown with P adsorbed to goethite

The actinomycete Gordonia sp. and the bacterium Pseudomonas fluorescens Pf-5 were grown in liquid media (pH 6.5) with phosphate adsorbed to the Fe-oxide/hydroxide goethite (Goe-P) and with soluble phosphate (0.1 mM or 1.0 mM P as KH2PO4). The two isolates showed distinct differences in their physiology. The pH of the medium was increased by Gordonia sp. by 1.1-1.7 units while it was decreased by P. fluorescens by 1.4-2.4 units. In all treatments the concentration of organic acids in the media with Gordonia sp. was up to 10 times lower (0.4-10.9 micromol L(-1)) than in media with P. fluorescens (33.4-84.4 micromol L(-1)). Gordonia sp. produced five different organic acids in varying amounts depending on P source and time. In contrast, P. fluorescens exuded mainly citrate and only small amounts of two to three other organic acids irrespective of P source or time.     

Computer-simulated evaluation of possible mechanisms for quenching heavy metal ion activity in plant vacuoles: I. Cadmium

Various mechanisms have been suggested for the quenching of Cd ion activity in plant vacuoles. These include solution complexation with organic acids and sulfhydryl-containing peptides and precipitation as sulfides. Because direct experimental support for these mechanisms is lacking and difficult to obtain, we have used a computer model to evaluate the quenching role of possible organic and inorganic ligands of tobacco cultured cells exposed to Cd. Results of this thermodynamic evaluation, which assumes that a chemical equilibrium state is met in the vacuole, support the conclusion that sulfhydryl-containing peptides and certain organic acids may form soluble Cd complexes. Although complexation of malate and oxalate with Cd is predicted to be less significant, citrate in the concentration range encountered in the tobacco cultured cell vacuoles has high potential for forming soluble complexes with Cd over the entire possible vacuolar pH range, especially 4.3 to 7.0, even in the presence of low levels of Cd-binding peptides. In addition, results show that inorganic chloride, sulfide (if present), and phosphate may also act to sequester Cd ion activity in the vacuole by forming soluble Cd-Cl and insoluble CdS and Cd-phosphate.