槐糖内酯的脂酶修饰

槐糖内酯是一种生物表面活性剂,槐糖内酯经脂酶修饰后,并未得到断裂内酯键的槐糖脂开环衍生物,而是有选择性地水解掉糖上的一个乙酰基。     

生物表面活性剂鼠李糖脂及其复配体系界面行为和性质的介观模拟

采用介观模拟耗散颗粒动力学（DPD）方法研究不同结构的鼠李糖脂在油/水界面行为差异和结构对活性的影响,并探讨了其与不同类型表面活性剂如十二烷基硫酸钠（SDS）、十二烷基苯磺酸钠（SDBS）、脂肪醇聚氧乙烯醚（AEO3）复配时体系的界面性质,给出不同结构的鼠李糖脂的行为特点及与常用合成表面活性剂在油/水界面的相互作用规律...     

科技信息

生物表面活性剂——槐糖脂 中科院上海有机化学所以农副产品下脚为原料,用生物工程手段,研制成功生物表面活性剂——槐糖脂。它来源于酵母的细胞膜,本身就是一个很好的营养成分,能促进皮肤的新陈代谢,无毒,具有乳化、分散、增溶等性能,国外已将其用于高级化妆品和儿童化妆品。槐糖脂的     

生物表面活性剂鼠李糖脂的纯化与表征

生物表面活性剂鼠李糖脂是微生物在一定条件下产生的次级代谢产物,其分子具有极性亲水基团和非极性亲油基团结构,通常表现出很高的表面活性和界面优先分配能力。可靠的分离提纯方法和成分鉴定手段是鼠李糖脂生产工艺成功的重要保证。实验通过好氧发酵培养铜绿假单胞菌CCTCC AB93066、酸沉降分离得到鼠李糖脂后,利用柱色谱提纯技术得到纯化的鼠李糖脂的单糖脂和二糖脂,最后采用高效液相色谱-质谱联用法进行成分鉴定。结果显示这两种鼠李糖脂均含有3种主要成分,其中单糖脂的主要成分为RhaC₁₀C₁₀、RhaC₁₀C₁₂-H₂、RhaC₁₀C₁₂,二糖脂的主要成分为Rha₂C₁₀C₁₀、Rha₂C₁₀C₁₂-H₂、Rha₂C₁₀C₁₂。该研究结果表明,铜绿假单胞菌CCTCC AB93066是一种良好的鼠李糖脂产生菌;酸沉降-柱色谱技术可以用于鼠李糖脂的深度提纯,且有较好的效果;而高效液相色谱-质谱联用技术对鼠李糖脂成分鉴定具有灵敏度高和准确性好等优点,是一种较为可靠的检测方法。     

鼠李糖脂应用于微乳毛细管电动色谱快速测定化妆品中激素类物质

采用生物表面活性剂鼠李糖脂建立了无需助表面活性剂的微乳体系,并应用于微乳毛细管电动色谱快速分析化妆品中皮质类激素泼尼松、泼尼松龙和氢化可的松。考察了pH值、鼠李糖脂浓度、离子强度、油相种类和浓度、分离温度、分离电压及进样电压和时间的影响,得出微乳体系最佳组成为0.1%(w/w)鼠李糖脂+0.8%(w/w)正庚烷+99.1%(w/w)硼砂缓冲液(80 mmol/L,pH 9.2)。分离温度20℃,分离电压20kV,电动进样10 kV×3 s,泼尼松、氢化可的松和泼尼松龙在9.4 min内可基线分离。重复进样7次,迁移时间和峰面积的RSD分别小于0.2%和5.0%。3种分析物线性范围均为5～100 mg/L;检出限分别为1.0,1.1和1.3 mg/L(S/N=3)。仅需简单萃取即可用于化妆品样品测定,回收率为81.6%～108%;RSD均小于4.8%。     

鼠李糖脂的合成及pH值对其表面活性和微乳微结构的影响

从铜绿假单胞菌发酵液中提取纯化鼠李糖脂生物表面活性剂. 用高效液相色谱-电喷雾质谱法(HPLC-ESI-MS)对鼠李糖脂提取物的组成进行了测定. 用临界胶束浓度(CMC)分析了pH值对其表面活性的影响, 用微乳液滴粒径和灼电位考察了pH值对鼠李糖脂/正庚烷/硼砂缓冲液微乳体系微结构的影响. 结果表明, 在弱碱性条件下(pH7.5-9.5), pH的变化对鼠李糖脂的表面活性和微乳微结构均有显著影响. pH小于9.0时, CMC随着pH的升高而降低, 在pH 9.0处达到最低. pH大于9.0时, CMC随着pH值的升高而逐渐升高. 这是氢键和极性头基间的静电排斥力共同作用的结果. 微乳液滴的粒径及灼电位绝对值都随pH值的升高呈增大趋势, 只在pH 9.0处例外. 少量十二烷基硫酸钠(SDS)或正丁醇的加入都使微乳粒径明显增大.     

κ-卡拉胶寡糖脂的合成及其结构鉴定

以κ-卡拉胶为原料, 通过稀酸降解并结合柱层析分离得到5个寡糖单体, 经还原胺化法将其与二棕榈酸酯磷脂酰乙醇胺(DPPE)偶联首次获得了5个拟糖脂. 应用高灵敏电喷雾离子化碰撞诱导解离串联质谱(ESI-CID-MS/MS)技术确定了其序列, 证明其分别为κ-卡拉胶三糖脂、五糖脂、七糖脂、九糖脂和十一糖脂. 该研究结果为硫酸寡糖脂的合成提供了参考方法, 尤其为寡糖生物芯片的制备以及深入开展寡糖与蛋白相互作用研究提供了基础.     

流动注射在线检测微生物代谢产物中糖脂类生物表面活性剂

菌种筛选工作是生物表面活性剂研究和制备的基础,主要是通过适时监测各出发菌株在发酵过程中生物表面活性剂产量和发酵性状稳定性实现的。目前常用的监测菌株产：表面活性剂情况的方法存在很多不足：发酵过程中停机取样易造成杂菌污染和发酵条件改变;发酵液用量大,测定周期长,实验操作繁杂。用流动注射分析(FIA)技术建立的在线     

甘油糖脂的合成工.1,2-二-O-脂酰基-3-O-(α-D-吡喃半乳糖基)-sn-甘油的合成

采用一种有效的方法合成了具有不同链长的二脂酰基α-D-半乳糖型甘油糖脂.将半乳糖烯丙苷化,重结晶得到α-D-半乳糖烯丙苷.随后将糖环的羟基用苄基保护,再利用OsO4/NMO(N-甲基-N-氧吗啉)的二羟基化条件将1-O烯丙基氧化成为邻二羟基,得到3-O-(2＇,3＇,4＇,6＇-四-O-苄基-α-D-吡喃半乳糖基)-sn-甘油.其与不同链长的脂酰氯进行脂酰化反应,然后氢解去掉苄基得到五种二脂酰基α-D-半乳糖苷基甘油.利用1H NMR,13C NMR,2D NMR,IR和MS对化合物的结构进行了确证.     

甘油糖脂的合成 Ⅰ.1,2-二-O-脂酰基-3-O-(α-D-吡喃半乳糖基)-sn-甘油的合成

采用一种有效的方法合成了具有不同链长的二脂酰基α D 半乳糖型甘油糖脂 .将半乳糖烯丙苷化 ,重结晶得到α D 半乳糖烯丙苷 .随后将糖环的羟基用苄基保护 ,再利用OsO4 /NMO(N 甲基 N 氧吗啉 )的二羟基化条件将 1 O烯丙基氧化成为邻二羟基 ,得到 3 O ( 2′ ,3′ ,4′ ,6′ 四 O 苄基 α D 吡喃半乳糖基 ) sn 甘油 .其与不同链长的脂酰氯进行脂酰化反应 ,然后氢解去掉苄基得到五种二脂酰基α D 半乳糖苷基甘油 .利用1HNMR ,13 CNMR ,2DNMR ,IR和MS对化合物的结构进行了确证 .     

Biosurfactants: Formulations,properties, and applications

In this review, we attempt to give an overview on the recent progress made on biosurfactants, surface-active biomolecules produced by microorganisms, which are a sustainable alternative to synthetic surfactants. Different biosurfactants, their production techniques, and their physical and chemical properties are discussed. There is a focus on recent studies related to surface properties and rheology of biosurfactants, both being properties which affect their ability to take part in a stable formulation. Biosurfactants can have applications in multiple different industrial sectors, such as agriculture, medicine, personal care, food, petroleum, etc. The specific properties important for applications in these sectors are discussed in detail.     

Rational design,properties, and applications of biosurfactants: a short review of recent advances

Biosurfactants combine physicochemical properties with biological activities. Although biosurfactants are often expressed by microorganisms, an increasing amount is produced by chemical synthesis. As many exist in the form of homologous compounds, it is often difficult to purify biosurfactants. But this has not limited the efforts to develop their commercial applications. In this short review, we have featured the recent advances in three important types of biosurfactants, lipopeptides, nucleolipids, and glycolipids. We have focused on comparing some of the key properties and functionalities between modern synthetic versions and their corresponding natural counterparts. We end the review by outlining the needs for not only strengthening their basic structure–property relationships through further research but also developing better technologies, irrespective of direct chemical synthesis or biological synthesis of biosurfactants through constructions of genetically engineered strains, to help advance the commercial use of biosurfactants.     

Isolation and partial characterization of a biosurfactant produced by Streptococcus thermophilus A

Isolation and characterization of the surface active components from the crude biosurfactant produced by Streptococcus thermophilus A was studied. A fraction rich in glycolipids was obtained by the fractionation of crude biosurfactant using hydrophobic interaction chromatography. Molecular (by Fourier transform infrared spectroscopy) and elemental compositions (by X-ray photoelectron spectroscopy) were determined. Critical micelle concentration achieved was 20g/l, allowing for a surface tension value of 36mJ/m(2). Moreover, this glycolipid rich fraction was found to be an anti-adhesive and antimicrobial agent against several bacterial and yeast strains isolated from explanted voice prostheses. Further purification steps should be carefully analyzed as each purification step will increase the costs and decreases the amounts of biosurfactants recovered.     

Biosurfactant production by cultivation of Bacillus atrophaeus ATCC 9372 in semidefined glucose/casein-based media

Biosurfactants are proteins with detergent, emulsifier, and antimicrobial actions that have potential application in environmental applications such as the treatment of organic pollutants and oil recovery. Bacillus atrophaeus strains are nonpathogenic and are suitable source of biosurfactants, among which is surfactin. The aim of this work is to establish a culture medium composition able to stimulate biosurfactants production by B. atrophaeus ATCC 9372. Batch cultivations were carried out in a rotary shaker at 150 rpm and 35 degrees C for 24 h on glucose-and/or casein-based semidefined culture media also containing sodium chloride, dibasic sodium phosphate, and soy flour. The addition of 14.0 g/L glucose in a culture medium containing 10.0 g/L of casein resulted in 17 times higher biosurfactant production (B(max)=635.0 mg/L). Besides, the simultaneous presence of digested casein (10.0 g/L), digested soy flour (3.0 g/L), and glucose (18.0 g/L) in the medium was responsible for a diauxic effect during cell growth. Once the diauxie started, the average biosurfactants concentration was 16.8% less than that observed before this phenomenon. The capability of B. atrophaeus strain to adapt its own metabolism to use several nutrients as energy sources and to preserve high levels of biosurfactants in the medium during the stationary phase is a promising feature for its possible application in biological treatments.     

Permeabilization of biological and artificial membranes by a bacterial dirhamnolipid produced by Pseudomonas aeruginosa

Pseudomonas aeruginosa, when cultured under the appropriate conditions, secretes rhamnolipids to the external medium. These glycolipids constitute one of the most interesting classes of biosurfactants so far. A dirhamnolipid fraction was isolated and purified from the crude biosurfactant, and its action on model and biological membranes was studied. Dirhamnolipid induced leakage of internal contents, as measured by the release of carboxyfluorescein, in phosphatidylcholine unilamellar vesicles, at concentrations below its CMC. Membrane solubilization was not observed within this concentration range. The presence of inverted cone-shaped lipids in the membrane, namely lysophosphatidylcholine, accelerated leakage, whereas cone-shaped lipids, like phosphatidylethanolamine, decreased leakage rate. Increasing concentrations of cholesterol protected the membrane against dirhamnolipid-induced leakage, which was totally abolished by the presence of 50 mol% of the sterol. Dirhamnolipid caused hemolysis of human erythrocytes through a lytic mechanism, as shown by the similar rates of K⁺ and hemoglobin leakage, and by the absence of effect of osmotic protectants. Scanning electron microscopy showed that the addition of the biosurfactant changed the usual disc shape of erythrocytes into that of spheroechinocytes. The results are discussed within the frame of the biological actions of dirhamnolipid, and the possible future applications of this biosurfactant.     

Synthesis and characterization of oligomaltose-grafted lipids with application to liposomes

Novel glycolipids, which contain 2 and 15 oligomaltose units and a phosphatidylethanolamine, were synthesized and characterized by FTIR and (1)H-NMR spectroscopies. The well-defined linear structure of the glycolipids was assured by an end-point conjugation strategy using selective oxidation of the reducing end groups of maltose oligosaccharides, followed by aminolysis with distearoylphosphatidylethanolamine. The intermediate acids react selectively with amines to form amide linkages, catalyzed by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxysuccinimide. Conformations of the glycolipids at the air-water interface were proposed based on the film balance measurements. The unique conformations of glycolipids at interfaces may offer advantages over traditional PEO-derived lipids in regard to their applications for sterically stabilizing liposomes. The glycolipids demonstrated the ability for sterically stabilizing liposome dispersions, as determined by turbidity measurements.     

Recent advances in the environmental applications of biosurfactants

Biosurfactants can be used for heavy metal or organic contaminant removal from contaminated soil or for bioremediation enhancement. Most research has been performed on the use of rhamnolipids. However, present and future studies involve new biosurfactants and new applications as sustainable, renewable additives for nanoparticle production and use.     

Emulsification potential of a newly isolated biosurfactant-producing bacterium, Rhodococcus sp. strain TA6

An indigenous biosurfactant producing bacterium, Rhodococcus sp. strain TA6 was isolated from Iranian oil contaminated soil using an efficient enrichment and screening method. During growth on sucrose and several hydrocarbon substrates as sole carbon source, the bacterium could produce biosurfactants. As a result of biosurfactant synthesis, the surface tension of the growth medium was reduced from 68mNm(-1) to values below 30mNm(-1). The biosurfactant was capable of forming stable emulsions with various hydrocarbons ranging from pentane to light motor oil. Preliminary chemical characterization revealed that the TA6 biosurfactant consisted of extracellular lipids and glycolipids. The biosurfactant was stable during exposure to high salinity (10% NaCl), elevated temperatures (120°C for 15min) and within a wide pH range (4.0-10.0). The culture broth was effective in recovering up to 70% of the residual oil from oil-saturated sand packs which indicates the potential value of the biosurfactant in enhanced oil recovery.     

Surfactants Used in Food Industry: A Review

The understanding of the formation, structures, and properties of emulsions is essential to the creation and stabilization of structures in food. The increasing use of surfactants, the identification of compounds with low toxicity and good surface activity properties is of great interest. The relevance of the major end points specified in the Organisation for Economic Co-operation and Development (OECD) guidelines for the hazard assessment of food chemicals is critically analyzed and main parameters are acute toxicity, subacute repeated studies, allergy, reproductive toxicity, long-term studies, and mutagenicity tests. We focus this article on surfactant association structures and food colloids. There is almost infinite number of combinations are organized and arranged in very complex internal microstructures with various types of assemblies such as dispersions, emulsions, foams, gels, etc. Low-mass surfactants are very mobile at the interface and they are particularly efficient reducing the interfacial tension. As a result, they rapidly coat the freshly created oil-water interface during emulsification. In this category, we mainly mentioned monoglycerides, lecithins, glycolipids, fatty alcohols and fatty acids. High-mass surfactants cover protein and polysacharide groups. The protein molecule may interpenetrate in the lipid phase to various degrees. The specific binding is predominantly electrostatic: The headgroups of the surfactants bind to groups of opposite charge on the protein. The saturation binding for anionic surfactants is pH-independent and seems to be controlled by the cooperative hydrophobic interactions. Polysaccharides and smallmolecule surfactants are two of the predominant groups of amphiphilic materials that have been explored for the stabilization of emulsions. One of the most important aspects of polymer-surfactant systems is their ability to control stability and rheology over a wide range of composition. Biocompatible, biodegradable, and/or nontoxic emulsion-based formulations have great potential for applications in the food. The combination of particular characteristics such as emulsifying, anti-adhesive and antimicrobial activities presented by biosurfactants suggests potential application as multipurpose ingredients or additives.     

Synthesis and characterization of novel alkoxy nonionic biosurfactants

A series of novel alkoxy nonionic biosurfactants were synthesized by ring-opening reaction of methoxy poly(ethylene glycols) and alkylene oxide. The chemical structures of these biosurfactants were confirmed by Fourier-transform infrared spectroscopy (FTIR) and ¹HNMR spectra. The surface tensions of these nonionic biosurfactants in the aqueous solutions were determined using a surface tensionmeter. The results showed that the critical micelle concentrations decreased with the increase of hydrophobic chain. However, due to the effect of intermolecular hydrogen bonding, the critical surface tensions of these nonionic biosurfactants increased with increasing the hydrophobic chain and were lower than those of conventional nonionic biosurfactants. Meanwhile, the effects of electrolytes on surface tension of these nonionic biosurfactants were slight. Due to the excellent surface activity, these alkoxy nonionic biosurfactants could have great potential in cleansing, oil recovery, and drug delivery.