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。     

The addition of ethanol as defoamer in fermentation of rhamnolipids

BACKGROUND: Rhamnolipids biosurfactants mainly produced by Pseudomonas aeruginosa have a wide range of potential applications. However, production of rhamnolipids on a large scale is constrained by severe foaming in fermentation. This study addressed the applicability of organic solvents as both defoamer and carbon substrate in rhamnolipids fermentation. RESULTS: In this work, although isopropanol and n‐butanol performed better defoaming activities against rhamnolipid‐induced foams, ethanol was focused on as a potential defoamer due to its high bioavailability and low toxicity in a shaking culture of P. aeruginosa ZJU. The most appropriate dose of ethanol addition was determined to be 1% (v/v) and the best time for addition was after 48 h of culture in shaking flasks. The capability of ethanol to control foaming was further illustrated during rhamnolipids fermentation in 2 L and 50 L bioreactors. In both fermentations, the addition of ethanol not only suppressed severe foaming but also supported cell growth. CONCLUSIONS: The use of ethanol as a defoamer is a potential strategy to avoid undesirable foam in fermentation of biosurfactant. Copyright © 2012 Society of Chemical Industry     

Biosurfactants for microbubble preparation and application

Biosurfactants can be classified by their chemical composition and their origin. This review briefly describes various classes of biosurfactants based on their origin and introduces a few of the most widely used biosurfactants. The current status and future trends in biosurfactant production are discussed, with an emphasis on those derived from plants. Following a brief introduction of the properties of microbubbles, recent progress in the application of microbubble technology to molecular imaging, wastewater treatment, and aerobic fermentation are presented. Several studies on the preparation, characterization and applications of biosurfactant-based microbubbles are reviewed.     

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。     

Recovery of biosurfactants by ultrafiltration

Ultrafiltration was used in a one-step method to purify and concentrate biosurfactants—surfactin and rhamnolipids—from culture supernatant fluids. The ability of surfactant molecules to form micelles at concentrations above the critical micelle concentration allows these aggregates to be retained by relatively high molecular weight cut-off membranes. Lower molecular weight impurities such as salts, free amino acids, peptides and small proteins are easily removed. Various molecular weight cut-off membranes were examined for the retention of surfactin and rhamnolipids (mol. wts 1036 and 802 respectively). Amicon XM 50 was the superior membrane for retention of surfactin and a 160-fold purification was rapidly achieved. The YM 10 membrane was the most appropriate for rhamnolipid recovery. Ultrafiltration can play an important role in biosurfactant purification as large volumes of media can be processed rapidly at extremely low cost.     

Rhamnolipids: Production in bacteria other than Pseudomonas aeruginosa

Rhamnolipids produced by Pseudomonas aeruginosa are the most studied biosurfactants due to their potential applications in a wide variety of industries and the high levels of their production. However, even though these biosurfactants are already produced at an industrial scale, the fact that P. aeruginosa is an opportunistic pathogen impose a restriction for its large scale production due to the intrinsic health hazard of the process. Other bacterial species that have been reported to be rhamnolipid producers are the pathogens Burkholderia mallei and B. pseudomallei, and recently the non‐pathogenic B. thailandensis. This short review presents information on rhamnolipid production by bacteria different from P. aeruginosa, as well as some approaches that have been taken to produce rhamnolipids using non‐pathogenic bacteria by genetic engineering of different bacteria. The low frequency of occurrence of rhamnolipid production among natural isolates that are not P. aeruginosa or Burkholderia, as well as the absence of orthologs of the genes involved in rhamnolipid synthesis (rhl genes) among the hundreds of sequenced bacterial genomes, suggest that the rare reported cases of these type of rhamnolipid‐producing bacteria have acquired this trait through horizontal gene transfer either from P. aeruginosa or from a member of Burkholderia.     

Microbial Oxidation of Medium Chain Fatty Alcohol in the Synthesis of Sophorolipids by Candida bombicola and its Physicochemical Characterization

Sophorolipids (SL) are glycolipid biosurfactants abundantly produced from different feedstocks by yeasts and have been widely developed for various applications. The amphipathic structures of sophorolipids imparts to them surfactant type properties. These biosurfactants are readily isolated in high yield and are nontoxic and biodegradable, which make them industrially interesting as surfactants or emulsifiers. Sophorolipid production was carried out using glucose as a hydrophilic source and lauryl alcohol C_12–14, as a hydrophobic source by Candida bombicola (ATCC 22214). Process economics and environmental attractiveness was increased by using a low cost substrate. Optimization studies were carried out where the effect of glucose concentration, pH, temperature and metal ions on sophorolipid production was studied. Optimum production of sophorolipid obtained using lauryl alcohol (SLLA) was achieved after 96 h, the initial pH of the medium was 6.0 with 10 % glucose at 30 °C. Primary characterization of SLLA was done by FTIR. The SLLA showed high physicochemical properties in terms of the surface activities when compared with synthetic surfactants including dodecyl tetraethylene glycol ether and sodium lauryl sulfate. The surface tension of SLLA thus obtained was found to be 24 mN/m with a critical micellar concentration (CMC) value of 0.68 mg/L. Antimicrobial testing showed that SLLA have potent antimicrobial activity against both gram negative bacteria, Escherichia coli (ATCC 8739) and gram positive cocci, Staphylococcus aureuss (ATCC 2079).     

Surfactin生物表面活性剂及其驱油研究进展

表面活性素（surfactin）是一类由革兰氏阳性的枯草芽孢杆菌产生的脂肽（lipopeptide）型生物表面活性剂,因其具有优于化学合成表面活性剂的若干优点,如低毒性、高生物降解性、更好的环境相容性,且在极端环境下稳定性好,在提高石油采收率方面有较好的应用潜力,但是目前只有少数的生物表面活性剂可以大规模生产实现工业化应用。本文介绍了surfactin生物表面活性剂的化学结构和生物合成机制,并对其发酵生产过程的影响因素进行分析,为提高其生产经济性探索不同的策略,例如使用更便宜的原材料、优化培养基组分、优化反应器等,系统论述了surfactin生物表面活性剂的驱油机理和其与化学合成表面活性剂的复配研究,同时针对其应用时的不足之处提出研究新思路。     

Biosurfactants as Alternatives to Chemosynthetic Surfactants in Controlling Bubble Behavior in the Flotation Process

To examine the usage of biosurfactants as potential alternatives to chemosynthetic surfactants in controlling bubble behavior in the flotation process, a high-speed photographic method was employed to measure the motion of single bubbles and the size distribution of bubbles in the presence of biosurfactants in a laboratory scale flotation column. Deionized water, rhamnolipid, tea saponin and t-C8phenolethoxylateEO9 were used for making various surfactant solutions. Bubble trajectory, dimensions, velocity and size distribution were then determined from the recorded frames using the image analysis software. The results show that similar to chemosynthetic surfactants, the addition of biosurfactants has significant effects on bubble motion and size distribution. The addition of a small amount of tea saponin can significantly dampen bubble deformation, slow down terminal velocity, stabilize bubble trajectory, reduce bubble size and increase the specific surface area of bubbles due to the Marangoni effect. In addition, the biosurfactant effect on bubble behavior has been also found to depend on their type and concentration. The effect of tea saponin, fairly close to C8phenolethoxylateEO9, is stronger than rhamnolipid. The findings in the present study suggest that such biosurfactant as tea saponin may be good substitutes of chemosynthetic surfactants to control bubble behavior in flotation operation.     

铜绿假单胞菌分泌鼠李糖脂能力对原油降解影响的研究

研究了铜绿假单胞菌分泌鼠李糖脂能力对原油生物降解的作用.将保存在原油中的铜绿假单胞菌转接至甘油培养基进行继代培养,观察到各继代培养下鼠李糖脂分泌量越高则该发酵液对原油的乳化降解能力就越强,推测该菌产鼠李糖脂能力决定了该培养液对原油的乳化与降解程度.鉴于此,分别将鼠李糖脂提取液、发酵液加入到原油培养基中,观察其各自的原油乳化程度的变化趋势,发现鼠李糖脂本身可以乳化原油但不能降解原油,且其乳化能力不如去菌体的发酵液.去菌体发酵液能很快地乳化原油而同样不能降解原油.只有含菌体的发酵液既能乳化又能降解原油.因此,可以认为鼠李糖脂本身具有乳化原油的能力,但是由铜绿假单胞菌同时分泌的其它表面活性物质可能协同鼠李糖脂更好地乳化原油以促进微生物对原油的利用与降解.     

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.     

Non-traditional Oils as Newer Feedstock for Rhamnolipids Production by <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> (ATCC 10145)

Oils and fats serve as one of the most important renewable feedstocks for various chemicals such as lubricants, textiles auxiliaries, biodiesel and surfactants. The oils have also proved themselves to be better substrates than glucose for production of biosurfactants such as rhamnolipids. Cost is major hindrance in the commercialization of these biosurfactants and fresh refined oils cannot be used for rhamnolipid production. Non-traditional oils such as jatropha oil, karanja oil and neem oil can be used as newer feedstock for the synthesis of rhamnolipids. Jatropha oil gave the highest production of rhamnolipids, 4.55 g/L in non-traditional oils and the rhamnolipid concentration was comparable to that of most common oils, sunflower oil giving 5.08 g/L of rhamnolipids. The jatropha oil contained mainly linoleic acid that showed the highest consumption rate as compared to oleic and palmitic acid. Neem oil produced a lower concentration of rhamnolipids (2.63 g/L) than other oils. Both monorhamnolipids and dirhamnolipids were synthesized using these oils. The product obtained can find high value specialty applications such as biomedical drug delivery and cosmetics.     

生物表面活性剂及其在环境工程中的应用

生物表面活性剂是由微生物产生的一类具有表面活性的生物化合物。相对于化学合成的表面活性剂,生物表面活性剂对生态系统安全无毒,且可生物降解,因而其应用前景非常广阔,并有可能成为化学合成表面活性剂的替代品或升级换代品。本文介绍了生物表面活性剂的结构性能、分类及其微生物来源和发展前景,着重介绍了它在环境工程中的应用。     

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。     

Biosurfactant production by microorganisms on unconventional carbon sources

In recent years natural biosurfactants have attracted attention because of their low toxicity, biodegradability, and ecological acceptability. However, for reasons of functionality and production cost, they are not competitive with chemical surfactants. Use of inexpensive substrates can drastically decrease the production cost of biosurfactants. This review describes the use of unconventional carbon sources for biosurfactant production. These sources include urban as well as agroindustrial wastes. With suitable engineering and microbiological modifications, these wastes can be used as substrates for large-scale production of biosurfactants.     

Increased Rhamnolipid Concentration and Productivity Achieved with Advanced Process Design

Rhamnolipids are biosurfactants having several applications. A major limitation in rhamnolipid production is low productivity, which decreases significantly during stationary-phase production. In this study, fermentations were first made with nitrogen-limited stationary phase. Long-term rhamnolipid production (up to 505 h) could be maintained with low-rate N-source addition but the intermittent cell growth led to lower productivity (q_p), particularly apparent at the highest addition rate. Four fermentations were next made under non-N-limited stationary phase without and with N-source supplementation; q_p could be much higher at 24–26 mg g⁻¹h⁻¹. Three final fermentations were designed to build the maximum cell concentration to 30 g L⁻¹ in two growth phases where the growth rate in the second phase was regulated by N-addition to control foaming. Cultures then entered non-N-limited stationary phase and were N-supplemented. At an optimal rate of 15% growth-N per 24 h to maintain cell activity, a highest rhamnolipid concentration of 120 g L⁻¹ was obtained after 144 h with overall productivity of 839 mg L⁻¹h⁻¹.     

Starmerella bombicola: recent advances on sophorolipid production and prospects of waste stream utilization

Sophorolipids are among the most extensively studied microbial biosurfactants. Starmerella bombicola is the most productive strain known for sophorolipid production, with volumetric productivity of up to 3.7 g L⁻¹ h⁻¹. This review focuses on the two most important aspects that have an influence on sophorolipid commercialization. Firstly, the metabolic engineering achievements of S. bombicola in the last decade are summarized. Secondly, three improvements of the bioprocess are described, including alternative feedstock, fermentation strategy and specially designed bioreactor. Discussion is made on the waste sources that have been used as feedstock for sophorolipid production, and the review also emphasizes the potential of food waste as nutrient source. Fermentation strategies that correlate with the specially designed bioreactors for commercialization are also discussed in detail. © 2018 Society of Chemical Industry     

Sorption and Transport of Naphthalene and Phenanthrene in Silica Sand in the Presence of Rhamnolipid Biosurfactant

Abstract

Sorption and transport of naphthalene and phenanthrene in silica sand in the presence of rhamnolipid biosurfactant were investigated by batch and column experiments. Naphthalene and phenanthrene had linear sorption isotherms on silica sand with partition coefficients decreasing with increasing rhamnolipid biosurfactant concentrations until the critical micellar concentration (CMC). After the CMC was reached, naphthalene and phenanthrene partition coefficients on silica sand increased with the increase of rhamnolipid biosurfactant concentrations. It was believed that micelles were formed when rhamnolipid biosurfactant was supplied at concentrations higher than the CMC, to which naphthalene and phenanthrene had higher affinity than silica sand. In column experiments, both naphthalene and phenanthrene had early breakthroughs in the presence of rhamnolipid biosurfactant than in its absence. Estimated naphthalene and phenanthrene retardation using naphthalene and phenanthrene batch sorption data was consistent with column experimental observations. Nevertheless, naphthalene and phenanthrene recovery decreased in answer to the presence of rhamnolipid biosurfactant at concentrations greater than the CMC, which was attributed to the entrapment of naphthalene and phenanthrene associated rhamnolipid biosurfactant micelles.     

生物表面活性剂在油田中的应用

生物表面活性剂和化学表面活性剂一样 ,有亲水基团和疏水基团 ,它是由微生物生长在水不溶的物质中并以它为食物源产生的。在油田中 ,生物表面活性剂是微生物提高采收率的重要机理 ,具有水溶性好、反应产物均一、无毒、安全、驱油效果好等特点。生物表面活性剂有 4种类型 :糖脂类、磷脂类、脂蛋白或缩氨酸脂和聚合物类。大多数生物表面活性剂是糖脂 ,是碳水化合物连接在长链脂肪酸上。目前 ,室内研究主要是研究各种反应条件对微生物产生生物表面活性剂和生物表面活性剂对原油的影响。矿场实验有地面发酵和地下发酵两种形式。从生物表面活性剂的特点、筛选产生生物表面活性剂的菌种、生物表面活性剂的类型、室内研究、矿场实验和今后的发展方向等 6个方面综述了油田中的生物表面活性剂的应用     

Enhanced removal of selected hydrocarbons from soil by Pseudomonas aeruginosa UG2 biosurfactants and some chemical surfactants

The ability of rhamnolipid biosurfactants produced by Pseudomonas aeruginosa UG2 to wash a model hydrocarbon mixture from unsaturated soil columns was studied. Both aliphatic and aromatic hydrocarbons were effectively removed without soil clogging with non-recirculating biosurfactant solutions. Recirculation of wash solutions did not substantially affect washing efficiency. Of the several chemical surfactants tested, only Triton X-100 provided comparable hydrocarbon washing efficiency without soil clogging. The results suggest that UG2 biosurfactants have the potential for remediation of hydrophobic pollutants in unsaturated soil.