Characterization and emulsification properties of rhamnolipid and sophorolipid biosurfactants and their applications

Due to their non-toxic nature, biodegradability and production from renewable resources, research has shown an increasing interest in the use of biosurfactants in a wide variety of applications. This paper reviews the characterization of rhamnolipid and sophorolipid biosurfactants based on their hydrophilicity/hydrophobicity and their ability to form microemulsions with a range of oils without additives. The use of the biosurfactants in applications such as detergency and vegetable oil extraction for biodiesel application is also discussed. Rhamnolipid was found to be a hydrophilic surfactant while sophorolipid was found to be very hydrophobic. Therefore, rhamnolipid and sophorolipid biosurfactants in mixtures showed robust performance in these applications.     

Biosurfactants: Recent advances

Surfactants find applications in a wide variety of industrial processes. Biomolecules that are amphiphilic and partition preferentially at interfaces are classified as biosurfactants. In terms of surface activity, heat and pH stability, many biosurfactants are comparable to synthetic surfactants. Therefore, as the environmental compatibility is becoming an increasingly important factor in selecting industrial chemicals, the commercialization of biosurfactant is gaining much attention. In this paper, the general properties and functions of biosurfactants are introduced. Strategies for development of biosurfactant assay, enhanced biosurfactant production, large scale fermentation, and product recovery are discussed. Also discussed are recent advances in the genetic engineering of biosurfactant production. The potential applications of biosurfactants in industrial processes and bioremediation are presented. Finally, comments on the application of enzymes for the production of surfactants are also made.     

鼠李糖脂生物表面活性剂及其纯化方法研究进展

鼠李糖脂生物表面活性剂是由微生物在一定的培养条件下分泌的次级代谢产物,具有良好的环境相容性,生产成本是制约其工业化应用的主要因素。综述了鼠李糖脂的常用纯化方法,并对其研究方向进行了展望。     

Precipitation and Recovery of Cellulase using Biosurfactant

Rhamnolipid and saponin were used as biosurfactant to form cellulase-biosurfactant complex systems. Acetone, ethanol, and methanol were tested recovery solvents, and among the three tested recovery solvents, acetone was the optimum one. Using acetone as recovery solvent and with the addition of 0.1 mM NaCl, the highest protein and activity recovery were yielded. The optimum conditions during the process for cellulase-rhamnolipid complex systems and cellulase-saponin complex systems were discovered. Two cellulase-biosurfactant complex systems were better than the cellulase-AOT complex system. Experimental results showed that biosurfactants have great potential in protein precipitation.     

Evaluation of production of lipopeptide biosurfactants and surfactin micelles by native Bacillus of Iran,for a broader application range

Surfactin is one of the most important lipopeptide biosurfactants obtained by biocatalysts of Bacillus subtilis. The aim of this study was to isolate surfactin-producing bacilli from native soils of the country (Iran), investigate their properties, convert surfactin to surfactin micelles, determine the properties of surfactin micelles and investigate the effect of starch-coated Fe⁰ and Fe³⁺ nanoparticles on the production of surfactin from B. subtilis. To do so, 20 bacilli were isolated from the native soil sample by heat shock method and genome sequenced by SrRNA16 method. The samples with strong β-hemolysis activity were screened as surfactant-producing strains. Two species of 61 and 63 (B. subtilis subspecies. Inaquosorum) were selected and examined by quantitative and qualitative screening tests such as hemolysis activity, surfactin production, droplet aggregation, emulsifying activity, and surface tension reduction in MSM medium containing Fe⁰ and Fe³⁺ nanoparticles. Surfactin was converted to surfactin micelles by sonication and confirmed by SEM. The antimicrobial and emulsifying activity and surface tension reduction of surfactin micelles were investigated. According to the results, the surface tension reduction of surfactin micelles was greater than that of surfactin. The strain 61 (99.7%) culture in 5 L bioreactors containing Fe³⁺ nanoparticles produced more surfactin than culture of the same strain without nanoparticles. This study presents an efficient method to increase the biosynthesis of microbial metabolites.     

假单胞菌O-2-2产鼠李糖脂的结构表征及理化性质

利用液相色谱/质谱联用仪分析了铜绿假单胞菌O-2-2以正十八烷为碳源所产鼠李糖脂生物表面活性剂的组成。共检出21种鼠李糖脂的同系物,都由1~2分子的鼠李糖和1~2个含β-羟基的碳链长度为8~12的饱和或不饱和脂肪酸构成;主要组分为α-L-吡喃鼠李糖苷-β-羟基癸酰-β-羟基癸酸和2-O-α-L-吡喃鼠李糖苷-α-L-吡喃鼠李糖苷-β-羟基癸酰-β-羟基癸酸。该糖脂类生物表面活性剂可将水的表面张力降至28·6mN/m,临界胶束浓度为1·3×10-4mol/L,在120℃加热4h或者在ρ(NaCl)=100g/L或ρ(CaCl2)=20g/L的盐溶液中仍能保持表面活性。     

采用超滤膜回收氯醋树脂离心母液

为了减少氯乙烯-醋酸乙烯树脂在聚合生产过程中废水的排放,采用中空纤维超滤膜浓缩分离离心母液和漂洗水。通过对膜装置运行过程的研究,确定了采用全时气水混合进料的方式运行效果最为良好,透过液可回用于生产,节约成本;浓缩液为随母液流失的树脂,回到生产线脱水干燥,提高产品产率。该方法大大降低了废水的排放量,减轻了污水处理系统的负荷。     

生物表面活性剂对城市污泥中铜和锌的去除研究

采用振荡淋洗的方法研究了生物表面活性剂鼠李糖脂浓度、p H、淋洗时间对城市污泥中Cu和Zn去除效果的影响。结果表明:随着鼠李糖脂浓度的增加,Cu和Zn的去除率增加,效果明显优于去离子水的去除,而鼠李糖脂对污泥中Cu的去除明显优于对Zn的去除,且鼠李糖脂在较高p H值下对Cu和Zn的去除效果较好;随着振荡时间的增加,Cu和Zn的去除率随之增加,最高去除率可高达63.9%、5.1%。本研究可为城市污泥的再利用所需要解决的问题提供参考方案。     

生物表面活性剂对疏水性有机物的增溶特性

在提高疏水性有机污染物的生物可利用性方面,生物表面活性剂的增溶效果是关键.通过实验测试了单一鼠李糖脂生物表面活性剂、复配表面活性剂(鼠李糖脂-非离子表面活性剂)对疏水性有机污染物增溶性能的影响,在此基础上,进一步考察了无机盐对复配表面活性剂增溶效果的影响.结果表明:鼠李糖脂质量浓度在临界胶束质量浓度之上时,长链烷烃和多...     

超滤技术在生物酶分离中的研究进展

该文综述了超滤技术的原理、分离过程、发酵液的性质以及超滤膜和超滤条件对生物酶超滤性能的影响。并从发酵液的处理、超滤膜和超滤过程的优化三方面出发,对近期提高超滤性能取得的成果进行了总结和讨论。最后指出生物酶超滤技术的未来发展方向有以下几点:超滤数学模型的开发;提高酶的稳定性;超滤膜的改进和开发;超滤工艺的改进。     

假单胞菌AB93066产鼠李糖脂发酵条件的优化

通过单因素实验和正交实验对铜绿假单胞杆菌AB93066产鼠李糖脂(RL)的摇瓶发酵培养基配方和产生规律进行了研究。结果表明,最佳培养基配方为:ρ(酵母膏)=0.2 g/L,ρ(豆油)=120 g/L,ρ(NaNO3)=6.5 g/L,ρ(KH2PO4)=1.0 g/L,ρ(Na2HPO4.12H2O)=1.0 g/L,ρ(MgSO4.7H2O)=0.1 g/L,ρ(FeSO4.7H2O)=0.2 g/L,pH=6.0。RL的收获期在发酵后156~168 h最佳。发酵生产RL的扩大实验表明,在最优发酵条件下RL的产量可达56 g/L以上,提取后的RL可将去离子水的表面张力降至29.01 mN/m。用高效液相色谱/质谱联用仪进一步分析了所提取的RL的组成,它分别为二鼠李糖脂(R1)和单鼠李糖脂(R2)两种同系物。R1和R2的表观临界胶束浓度(CMC)分别为0.03 mmol/L和0.04 mmol/L。     

Chemical Structure,Property and Potential Applications of Biosurfactants Produced by Bacillus subtilis in Petroleum Recovery and Spill Mitigation

Lipopeptides produced by microorganisms are one of the five major classes of biosurfactants known and they have received much attention from scientific and industrial communities due to their powerful interfacial and biological activities as well as environmentally friendly characteristics. Microbially produced lipopeptides are a series of chemical structural analogues of different families and, among them, 26 families covering about 90 lipopeptide compounds have been reported in the last two decades. This paper reviews the chemical structural characteristics and molecular behaviors of surfactin, one of the representative lipopeptides of the 26 families. In particular, two novel surfactin molecules isolated from cell-free cultures of Bacillus subtilis HSO121 are presented. Surfactins exhibit strong self-assembly ability to form sphere-like micelles and larger aggregates at very low concentrations. The amphipathic and surface properties of surfactins are related to the existence of the minor polar and major hydrophobic domains in the three 3-D conformations. In addition, the application potential of surfactin in bioremediation of oil spills and oil contaminants, and microbial enhanced oil recovery are discussed.     

泡沫浮选耦合膜过滤回收有机废水中纳米TiO2光催化剂的工艺

本研究的目的是开发一种新型的泡沫浮选耦合超滤技术的方法,以实现从有机废液体系中经济、高效地回收纳米TiO₂光催化剂。首先,对超滤膜分离有机废液中纳米TiO₂光催化剂的使用效率,包括透过通量和截留率进行评价。随后,为了减少超滤操作进料液中纳米TiO₂光催化剂的浓度,在泡沫浮选阶段确定以阳离子表面活性剂——十六烷基三甲基溴化铵（CTAB）作为捕获剂,研究了CTAB浓度、气体体积流速、分布器孔径对泡沫浮选回收纳米TiO₂光催化剂富集效率的影响。最后,确定泡沫浮选耦合超滤耦合回收纳米TiO₂光催化剂的工艺条件。试验结果表明,采用耦合工艺,在pH 7.0、CTAB浓度0.20g/L、气体体积流速15mL/min以及分布器孔径180μm的条件下,纳米TiO₂光催化剂富集比和回收率分别为22.52和99%,同时膜的使用寿命较非耦合操作提高了133％。     

Synthesis of brushite particles in reverse microemulsions of the biosurfactant surfactin

In this study the "green chemistry" use of the biosurfactant surfactin for the synthesis of calcium phosphate using the reverse microemulsion technique was demonstrated. Calcium phosphates are bioactive materials that are a major constituent of human teeth and bone tissue. A reverse microemulsion technique with surfactin was used to produce nanocrystalline brushite particles. Structural diversity (analyzed by SEM and TEM) resulted from different water to surfactin ratios (W/S; 250, 500, 1000 and 40,000). The particle sizes were found to be in the 16-200 nm range. Morphological variety was observed in the as-synthesized microemulsions, which consisted of nanospheres (~16 nm in diameter) and needle-like (8-14 nm in diameter and 80-100 nm in length) noncalcinated particles. However, the calcinated products included nanospheres (50-200 nm in diameter), oval (~300 nm in diameter) and nanorod (200-400 nm in length) particles. FTIR and XRD analysis confirmed the formation of brushite nanoparticles in the as-synthesized products, while calcium pyrophosphate was produced after calcination. These results indicate that the reverse microemulsion technique using surfactin is a green process suitable for the synthesis of nanoparticles.     

生物表面活性剂在日化行业的研究及应用进展

综述了生物表面活性剂在日化行业的研究进展和用于日化行业的生物表面活性剂新产品,探讨了生物表面活性剂在日化行业的应用优势及限制因素,指出了应对措施并对其在日化行业的应用前景进行了展望。     

Treatment of fishery washing water by ultrafiltration

The recovery and concentration of proteins from the waste water of a fish plant was achieved by ultrafiltration. Two UF modules equipped with Ceraver and Patterson Candy International (PCI) membranes were tested. Despite different cut-off values, similar apparent rejection coefficients (70% and 80% respectively) were obtained. Optimum economic conditions were established, corresponding to average transmembrane pressures of 2·2 × 10⁵ and 3·8 × 10⁵ Pa and tangential flow rates of 6·0 and 0·47 m s⁻¹ for Ceraver and PCI membranes, respectively. The protein concentration in the feed solution was increased from 5 to 35 g dm⁻³. The study showed that the method could reduce pollution due to organic matter by decreasing the value of the Biological Oxygen Demand after 5 days (BOD₅) by about 80%.     

生物表面活性剂鼠李糖脂发酵条件的优化及绿色提取新工艺研究

通过正交实验对铜绿假单胞杆菌产鼠李糖脂（RL）的发酵条件进行了优化,并采用预处理酸沉淀冷冻干燥法新工艺提取RL。在最优发酵条件下RL的产量可达56 g/L以上。提取后的RL由二鼠李糖脂和单鼠李糖脂两种同系物组成,可将去离子水的表面张力降至29.01 mN/m。该RL提取工艺是一项绿色工艺。     

超滤膜直接过滤地表水试验

采用截留相对分子质量为50000的国产聚丙烯腈中空纤维超滤膜,进行地表水直接过滤试验。采用浊度为5 NTU和15NTU的原水进行试验,当膜的特性通量趋于稳定时,其值分别下降到初始值的40%和42%,结果表明在相同操作条件下,浊度的高低与膜污染程度的轻重正相关,已污染的膜经水力清洗和化学清洗后膜的特性通量恢复率达到98%,清洗效果比较理想。     

Hemicelluloses separation from caustic-containing process stream by ultrafiltration

The present work aimed to study the performance of ultrafiltration (UF) membranes for hemicelluloses separation, from a caustic-containing highly alkaline, cellulose purification solvent stream of viscose rayon production process, and to understand the membrane behaviour, effect of multiple use cycle, identify potential performance drawbacks and propose possible solutions. Screening experiments showed that an UF membrane with a nominal molecular weight cut-off value of 3 kDa can be used to separate hemicelluloses from alkaline process stream. UF membrane was found to be prone to performance deterioration with time due to fouling. Higher feed temperature helped in improving the membrane flux values while maintaining hemicelluloses retention.