Koichiro Shiomori

Extraction characteristic of bovine serum albumin using sodium bis(2-ethylhexyl) sulfosuccinate reverse micelles

Abstract The extraction of bovine serum albumin (BSA, M. W. 66 kDa, pI 4.9) was carried out using a reverse micelle consisting of sodium bis(2-ethylhexyl) sulfosuccinate (AOT). When CaCl 2 or MgCl 2 was used, BSA could be extracted at a pH higher than the pI of BSA. This effective extraction at a pH higher than the pI was considered to be caused by the modification of interactions between the protein and the micelles by the divalent cations. For KCl and NaCl, BSA could be extracted only at high concentrations of AOT and within a narrow pH range, and maximum extraction was achieved at the pH values of 5.5 for NaCl and 5.0 for KCl. The BSA extraction efficiency decreased sharply at high concentrations of NaCl and KCl. Sufficient concentrations of AOT in the organic phase, which depends on the salt type and its concentration, are required to extract BSA into the organic phase. In the range of insufficient concentration of AOT, aggregation and precipitation of BSA with AOT occurred in preference to extraction. BSA extracted into the organic phase could be back-extracted into a fresh aqueous phase at high pH values and high salt concentrations. The conformation of BSA was maintained to a large extent during the extraction process.

Hydrolysis rates of olive oil by lipase in a monodispersed O/W emulsion system using membrane emulsification

Hydrolysis of olive oil in isooctane by lipase from Candida cylindracea in an aqueous solution was carried out in a polydispersed emulsion system prepared by a homogenizer and in a monodispersed emulsion system prepared by the shirasu-porous-glass (SPG) membrane emulsification method. An emulsion system consisting of both SDS and PVA at pH 7.8 was best suited for the reaction. In the monodispersed emulsion, the droplet diameter was controlled by the pore diameter of the SPG membrane to give droplets with a narrow diameter distribution range. The rate of hydrolysis was affected by the concentrations of olive oil and lipase, the interfacial area and the emulsion droplets diameter. The kinetic data were interpreted by the interfacial reaction model, in which desorption of the product from the interface was the rate determining step. The equilibrium constant of the adsorption of lipase at the interface were very small compared with that obtained in the isothermal adsorption equilibrium of lipase at the interface without a surfactant. The equilibrium constants of the reaction between lipase adsorbed at the interface and olive oil in the organic phase were nearly of the same order as those obtained in the Lewis cell and the VibroMixer. The desorption rate constants of the product were very large compared with that in the Lewis cell.

Lactic acid bacteria-enclosing poly(ɛ-caprolactone) microcapsules as soil bioamendment

Free plant growth-promoting bacteria in soil bioamendments (SBA) are easily outnumbered by competitors and predators in agricultural soils. Microencapsulation of the bacteria is an effective technique that provides a suitable microenvironment for their survival. In this study, we attempted to prepare poly(epsilon-caprolactone) (PCL) microcapsules enclosing lactic acid bacteria (LAB), a plant growth-promoting bacteria, using the solvent-evaporation method via water-in-oil-in-water (W/O/W) emulsion. Three preparation parameters in the emulsion system were optimized based on the lactic acid production activity of the encapsulated LAB. A sodium alginate aqueous solution suspending the bacteria, a dichloromethane solution with dissolved PCL, and a poly(vinyl alcohol) aqueous solution were used as the inner aqueous phase (W(i)), the oil phase (O), and the outer aqueous phase (W(o)), respectively. Suitable volume ratio of W(i) to O, concentration of sodium alginate in W(i), and the molecular weight of PCL in O were 0.1, 1.0%, and 40 kDa, respectively. The lactic acid production activity of the microcapsules prepared under the optimized conditions was approximately nine times higher than that of commercial SBA. Application to soil demonstrated that the microcapsules are effective in the removal of the root-knot nematodes.

Characteristics and kinetics of lipase-catalyzed hydrolysis of olive oil in a reverse micellar system

Abstract The hydrolysis rates of olive oil catalyzed by lipase were measured in a reverse micellar system using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) under various conditions. The maximum activity of lipase in the reverse micelles was obtained between pH 6.3 and 7.3. The dependence of the activity on the water content, Wo, was influenced by the concentrations of both AOT and lipase. The activity at Wo = 7 decreased with increasing lipase concentration when the AOT concentration was below 100 mol/m3. The stability of the lipase in the micelles decreased with increases in the value of Wo and in the concentration of AOT. The hydrolysis reaction catalyzed by lipase in the reverse micelles was interpreted by a reaction model based on the interfacial reaction between lipase adsorbed at the interface and the substrate in the organic phase. The rate is controlled by the desorption step of free fatty acids into the organic solution. The desorption rate constants of fatty acids produced were independent of the AOT concentration at a fixed Wo, and were of nearly the same order of magnitude as that obtained in the emulsion system.

Hydrolysis kinetics of olive oil with lipase in a transfer cell

Abstract The hydrolysis kinetics of olive oil dissolved in i-octane with lipase in water was investigated in a biphasic system under various conditions using a Lewis-type transfer cell. The formation rates of fatty acids were found to be affected by the volume of the aqueous solution and the concentrations of lipase and olive oil. The rates followed a reaction scheme in which either the decomposition of a complex on the interface or the desorption of fatty acids formed on the interface into the organic solution was postulated as the rate-determining step. Parameters for the interfacial reaction rate and adsorption equilibrium of lipase were determined so as to satisfy the experimental result.

Hydrolysis of olive oil with lipase in a “VibroMixer”

Hydrolysis of olive oil in i-octane with Candida cylindracea lipase in aqueous solution was performed in a VibroMixer reactor. The kinetic data were interpreted by the interfacial reaction model, whose rate was controlled by the desorption of the product as shown in a previous study of the Lewis-type transfer cell. The desorption rate constant of the product and the equilibrium constant of the reaction between lipase and olive oil were evaluated using the adsorption parameters of lipase. The desorption rate constant was 1.3 × 103 mol/m2h, which was about 3 × 103 times greater than that observed in the Lewis cell. The desorption rate was suspected to be facilitated by the repeated dispersion and coalescence of the oil phase. The equilibrium constant of the interfacial reaction was nearly of the same order as that obtained in the Lewis cell.

Extraction and Separation of Precious Metals by a Column Packed with Divinylbenzene Homopolymeric Microcapsule Containing Tri‐n‐octylamine

Abstract The separation of palladium, platinum, and gold was investigated using a column packed with divinylbenzene homopolymeric microcapsules containing tri‐n‐octylamine (TOA). The extraction of precious metals except platinum using the microcapsules progresses by means of the same reaction proposed in a solvent extraction system. The microcapsules also effectively extracted precious metals from an aqueous hydrochloric acid medium in the column operation. The breakthrough point is delayed in the following order: platinum, palladium, and gold. Almost all TOA molecules enclosed in the microcapsules can act on the extraction reaction with precious metals, which was confirmed by the calculation of the concentration of precious metals extracted into the microcapsules based on the breakthrough curve of each precious metal. By selecting the appropriate eluent, palladium, gold, and platinum were successfully eluted from the column using an 8.0 mol/dm3 aqueous HCI solution, a 0.1 mol/dm3 thiourea in 0.1 mol/dm3 aqueous HCI solution, and a 0.5 mol/dm3 ethylenediamine in 0.1 mol/dm3 aqueous NaOH solution, respectively. By feeding the eluent stepwise into the column in this order, the mutual separation of precious metals can be successfully achieved.

Kinetics for Oxidation of Squalene.

スクアレンの酸化反応速度を気泡塔型反応器を用いて測定した. 酸化反応は, 過酸化物の生成速度が緩やかな誘導期とその生成速度が自触媒的に増加する加速期の二つの段階によって進行することがわかった. 過酸化物濃度は加速期の後半で最大となり, その後緩やかに減少した. 紫外/可視吸収および化学発光検出器を備えた高速液体クロマトグラフィーを用いてスクアレンおよび6種の過酸化物生成挙動を確認した. 酸化反応によって生成した過酸化物は高温で容易に分解され, 分解生成物の主成分はカルボニル化合物であることがわかった. 実験結果を脂質ラジカルを考慮した連鎖反応モデルに基づいて解析し, 酸化速度式を導出した. スクアレンの酸化反応速度は, 誘導期および加速期において, それぞれ過酸化物濃度に関して0次および1次で表現できた.

Behavior of Ethyl Linoleate in Batch Rectification of Aqueous Ethanol Solution Containing Linoleic Acid

焼酎もろみに含まれる種々の脂肪酸はクエン酸存在下, 蒸留缶内でエタノールと反応して, より揮発度の高いエステルに変化し, 蒸留生成物として酒質に影響をおよぼす.本研究では, 焼酎もろみのモデル水溶液中におけるエタノールとリノール酸とのエステル化反応速度を測定した.これらの反応速度はリノール酸の濃度, 触媒としてのクエン酸濃度, エタノール濃度及び温度の影響を受ける.リノール酸のエステル化反応速度式は, リノール酸の濃度, CL, クエン酸の濃度, CC,.エタノール濃度, CE, 及び温度の関数として次式で表わされることがわかった.r=kL×CLl×CCm×CEnリノール酸エチルの生成速度に影響を及ぼすリノール酸濃度, クエン酸濃度及びエタノール濃度の反応次数l, m及びnの値を求めるとともに, 速度定数, kL, を温度の関数として求めた.さらに, リノール酸またはこのエステル体を含むエタノール水溶液の蒸留を行い, 缶内のエステル化反応によるエステル生成とその蒸留挙動について検討した.リノール酸エチルの留出挙動が, 蒸留缶内におけるエステル化反応速度とエタノール水溶液中のリノール酸エチルの気液平衡から予測できることがわかった.

Adsorption Equilibria of the Organic Acids on Activated Carbon at Various Temperatures.

283-323Kで, 活性炭に対する酢酸, プロピオン酸, クロトン酸, シュウ酸, コハク酸, イタコン酸, マレイン酸, 乳酸, クエン酸の吸着平衡を広い濃度範囲で測定した.脂肪酸の吸着量は温度と共に減少した.吸着挙動は, 低濃度域ではLangmuir型単分子吸着式, 高濃度までの広い濃度域ではB.E.T.型多分子層吸着式で説明された.B.E.T.式中の相対濃度として, 脂肪酸の液体状態における純物質濃度に対する平衡濃度の割合を用いて, 全濃度域での吸着平衡結果を説明することができた.単分子層および多分子層吸着平衡定数は温度が高くなると減少し, 脂肪酸の疎水性と相関される傾向を示した.