生物表面活性剂应用概述及其发展前景

随着人们崇尚自然和环保意识的增强,生物表面活性剂将成为化学合成表面活性剂的理想替代品,并有更加广阔的应用前景及发展潜力.本文介绍了生物表面活性剂的特性及其生产制备方法,并综述了近几年生物表面活性剂在石油、洗涤、医药、食品等工业领域的应用与研究进展,主要介绍了利用生物表面活性剂在提高石油采收率等方面的应用,探讨了今后生物表面活性剂的主要发展方向.     

生物表面活性剂及在油田中的应用

生物表面活性剂是由微生物产生的一种生物大分子物质,具有一些优于化学合成表面活性剂的特性,其应用前景十分广阔。本文简述了其种类、特性、生产方法及在石油工业中的应用。     

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。     

特种表面活性剂和功能性表面活性剂(Ⅶ)——生物表面活性剂的性能及应用研究进展

简要介绍了生物表面活性剂的分类及其合成方法;较详细地介绍了生物表面活性剂与化学合成表面活性剂相似和优于化学合成表面活性剂的特性以及生物表面活性剂的生理学功能;重点阐述了生物表面活性剂在石油工业、环境工程、食品工业、化妆品工业及医学领域等方面的应用现状;最后展望了生物表面活性剂的应用前景。     

生物表面活性剂及其应用

简要介绍了生物表面活性剂相对于化学合成表面活性剂的特性、分类和制备方法;重点综述了生物表面活性剂在石油、医药、化妆品、农业、食品和环境工程等领域的应用,展现了生物表面活性剂有望取代化学合成表面活性剂,成为绿色表面活性剂发展的重要方向,提出了生物表面活性剂目前存在的主要问题和发展前景.     

生物破乳剂的应用研究进展

微生物在一定条件下培养时,其代谢过程中分泌产生的一些具有一定表面活性、集亲水基和疏水基结构于一分子内的两亲化合物,称为生物表面活性剂。同化学合成的表面活性剂一样,具有润湿、分散、乳化、破乳、消泡、去污、抗静电等作用。此外,生物表面活性剂还具有以下优点：可以用微生物方法引进化学方法难以合成的化学基团;无毒且能被生物完全降解,对环境不造成污染;微生物发酵生产工艺简便。由于生物表面活性剂的独特优点,其在环境保护、石油工业、食品工业、农业等领域的应用受到越来越多的重视,并有可能成为化学合成表面活性剂的替代品或升级换代。生物破乳剂作为生物表面活性剂的一类在工业应用中也具有广阔的前景,本文重点介绍生物破乳剂的研究与应用进展。     

微生物表面活性剂的生产和潜在生物技术应用(待续)

微生物表面活性剂是两亲分子,其由亲水部分和疏水部分组成。根据其分子量的不同,可将其分为生物乳化剂和生物表面活性剂2大类。微生物表面活性剂根据其化学性质和制备所用的生物体的不同分成很多种类。这些生物分子由包括真菌、细菌和酵母在内的各类微生物所制备。其生产受到底物类型、发酵工艺和微生物菌株的显著影响。由于微生物固有的多功能特性和各种合成能力,微生物表面活性剂在很多工业和生物医学应用中比化学合成的表面活性剂更受青睐,包括生物修复(治理)、采油、作为洗衣粉配方成分,食品和化妆品行业中的乳液稳定剂。作为一种有前途的、具有广泛功能的生物分子,本文对微生物表面活性剂的生产及其在生物技术中的应用进行了综述。     

糖脂类生物表面活性剂的性质及其潜在应用进展

与化学合成的表面活性剂相比微生物产生的生物表面活性剂具有表面活性高、良好的抑菌作用以及环境友好等独特的性质。其中糖脂类生物表面活性剂由于其高产量和多功能生化特性,成为最有发展前途的生物表面活性剂之一。本文综述了糖脂类生物表面活性剂的特性及潜在的应用。     

微生物合成的糖脂类生物表面活性剂

介绍了糖脂类生物表面活性剂的种类、理化特性、微生物合成的方法及应用和发展趋势。相对于化学合成的表面活性剂,微生物糖脂具有可生物降解、在高温或极端pH环境下仍然有效和无毒或低毒等优点,有些微生物糖脂还表现出高效的抗菌、防霉和抗病毒特性。但目前通过微生物合成糖脂的生产成本仍比化学合成的高,因此降低其生产成本是当前研究开发的热点和主要发展方向。     

生物表面活性剂及其在食品中的应用

生物表面活性剂是天然表面活性剂的一个分支,具有与化学合成表面活性剂相区别的理化特性,对生物表面活性剂的发展符合目前发展绿色表面活性剂和生物应用技术的趋势。本文着重论述了生物表面活性剂在食品中的发展和应用．以及现在的实际问题和未来的发展方向。     

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     

Importance of the Long-Chain Fatty Acid Beta-Hydroxylating Cytochrome P450 Enzyme YbdT for Lipopeptide Biosynthesis in Bacillus subtilis Strain OKB105

Bacillus species produce extracellular, surface-active lipopeptides such as surfactin that have wide applications in industry and medicine. The steps involved in the synthesis of 3-hydroxyacyl-coenzyme A (CoA) substrates needed for surfactin biosynthesis are not understood. Cell-free extracts of Bacillus subtilis strain OKB105 synthesized lipopeptide biosurfactants in presence of l-amino acids, myristic acid, coenzyme A, ATP, and H(2)O(2), which suggested that 3-hydroxylation occurs prior to CoA ligation of the long chain fatty acids (LCFAs). We hypothesized that YbdT, a cytochrome P450 enzyme known to beta-hydroxylate LCFAs, functions to form 3-hydroxy fatty acids for lipopeptide biosynthesis. An in-frame mutation of ybdT was constructed and the resulting mutant strain (NHY1) produced predominantly non-hydroxylated lipopeptide with diminished biosurfactant and beta-hemolytic activities. Mass spectrometry showed that 95.6% of the fatty acids in the NHY1 biosurfactant were non-hydroxylated compared to only ～61% in the OKB105 biosurfactant. Cell-free extracts of the NHY1 synthesized surfactin containing 3-hydroxymyristic acid from 3-hydroxymyristoyl-CoA at a specific activity similar to that of the wild type (17 ± 2 versus 17.4 ± 6 ng biosurfactant min(-1)·ng·protein(-1), respectively). These results showed that the mutation did not affect any function needed to synthesize surfactin once the 3-hydroxyacyl-CoA substrate was formed and that YbdT functions to supply 3-hydroxy fatty acid for surfactin biosynthesis. The fact that YbdT is a peroxidase could explain why biosurfactant production is rarely observed in anaerobically grown Bacillus species. Manipulation of LCFA specificity of YbdT could provide a new route to produce biosurfactants with activities tailored to specific functions.     

Sustainable Production of Biosurfactant from Agro-Industrial Oil Wastes by Bacillus subtilis and Its Potential Application as Antioxidant and ACE Inhibitor

The microbial conversion of agro-industrial oil wastes into biosurfactants shows promise as a biomass refinery approach. In this study, Bacillus subtilis #309 was applied to produce surfactin using rapeseed and sunflower cakes, the most common oil processing side products in Europe. Studies of the chemical composition of the substrates were performed, to determine the feasibility of oil cakes for surfactin production. Initially, screening of proteolytic and lipolytic activity was performed to establish the capability of B. subtilis #309 for substrate utilization and hence effective surfactin production. B. subtilis #309 showed both proteolytic and lipolytic activity. The process of surfactin production was carefully analyzed by measurement of the surfactin concentration, pH, surface tension (ST) and emulsification index (E₂₄). The maximal surfactin concentration in the sunflower and rapeseed cake medium reached 1.19 ± 0.03 and 1.45 ± 0.09 g/L, respectively. At the same time, a progressive decrease in the surface tension and increase in emulsification activity were observed. The results confirmed the occurrence of various surfactin homologues, while the surfactin C₁₅ was the dominant one. Finally, the analysis of surfactin biological function exhibited antioxidant activity and significant angiotensin-converting enzyme (ACE)-inhibitory activity. The half-maximal inhibitory concentration (IC₅₀) value for ACE inhibition was found to be 0.62 mg/mL for surfactin. Molecular docking of the surfactin molecule to the ACE domains confirmed its inhibitory activity against ACE. Several interactions, such as hydrophobic terms, hydrogen bonds and van der Waals interactions, were involved in the complex stabilization. To the best of our knowledge, this is the first report describing the effect of a lipopeptide biosurfactant, surfactin, produced by B. subtilis for multifunctional properties in vitro, namely the ACE-inhibitory activity and the antioxidant properties, using different assays, such as 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). Thus, the ACE-inhibitory lipopeptide biosurfactant shows promise to be used as a natural antihypertensive agent.     

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.     

The effects of a biosurfactant on oxygen transfer in a cyclone column reactor

A laboratory-scale cyclone column reactor was tested to determine how its oxygen transfer characteristics were affected by surfactants in the liquid medium. The volumetric oxygen transfer coefficient was greatly decreased by small quantities of the synthetic surfactants dodecyltrimethylammonium bromide and sodium dodecylsulfate, and the biosurfactant surfactin produced by Bacillus subtilis (ATCC 21332). Since the gas holdup fraction was generally increased due to foaming, the effectiveness of the surfactants was probably due to an increase in the interfacial film resistance. B. subtilis was grown in the cyclone column to 0.6 g dm^?3 with a significant level of surfactin produced while maintaining at least 75% oxygen saturation in the broth. Process optimization and scale-up of surfactin production will have to consider oxygen transfer as a key parameter.     

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.     

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.     

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.     

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.