脂肽类生物表面活性剂研究概况

脂肽是一类微生物源的表面活性剂,在各领域具有良好的应用潜力。文章对脂肽的化学结构、理化性质、生产菌种、生物合成机理、主要应用、研究重点进行了论述。同时指出,居高不下的生产成本是当前制约脂肽发展的主要因素。未来研究的重点,将紧紧围绕如何提高产量和降低成本而展开。一是在菌株的筛选方面,应用基因改造和诱变技术,获得产量更高、遗传性更稳定的高产菌株;二是开发更适合工业化生产的分离纯化技术;三是进一步拓宽廉价原材料的范围,降低生产成本;四是更深入的研究脂肽的结构、活性,为脂肽的开发应用创造更广阔的前景。     

关于环状脂肽类物质的结构和生物特性分析

环脂肽是由微生物发酵生成的次级代谢产物,由亲水的肽环与亲油的脂肪烃组成,具有抗真菌、抗肿瘤和抗病毒等生物学功能。为了研发新型抗生素,综述了细菌来源的环脂肽、蓝细菌的环脂肽和其它微生物的环脂肽类化合物的化学结构,并介绍了环脂肽的抗肿瘤、抗菌、抗炎和其它生物学活性。     

脂肽类生物表面活性剂的研究进展

脂肽类生物表面活性剂是一类由微生物产生的次级代谢产物,具有独特的化学结构,表现出优良的表面活性和生理特性。简介了脂肽类生物表面活性剂的产生菌及其种类,重点介绍了海洋微生物所产的脂肽类表面活性剂,并展望了其研究前景。     

脂肽类生物表面活性剂在微生物采油中的应用

随着科学技术的进步,越来越多的生物物质被运用到石油开采过程中,同时发挥着重要的积极作用。脂肽是生物代谢过程中产生的一种具有表面活性功能的活性剂,在提高原油采收率方面具有很好的发展潜力。本文主要是在分析脂肽类生物表面活性剂的结构与特性的基础上,探讨其在微生物采油中的具体应用。     

具有强广谱抗菌活性的γ-α肽

正本发明涉及一种新型抗菌剂,称为γ-α肽。本发明提供各种类型的γ-α肽,例如线性γ-α肽、环状γ-α肽和脂化γ-α肽。本发明的γ-α肽被设计为在稳定和无毒的情况下发挥抗菌活性。γ-α肽似乎也不会导致处理过的微生物产生耐药性。因此,所公开的γ-α肽可用于治疗与致病微生物相关的各种医疗条件。     

生物表活剂处理含油污泥的研究进展与应用

讨论了生物表活剂处理含油污泥的机理，介绍了鼠李糖脂、槐糖脂和脂肽类生物表活剂在油泥中回收原油的应用，分析了生物表活剂强化微生物降解石油烃污染物的作用机理和应用，并提出了对生物表活剂处理油泥未来研究趋势的一些见解。     

微生物合成生物表面活性剂研究进展

生物表面活性剂一般是由微生物产生的一类两性分子的表面活性物质。与化学表面活性剂相比,微生物合成的表面活性剂拥有生物降解、环境友好、耐极端环境和低毒性等特点。生物表面活性剂主要包括糖脂、脂肽、脂蛋白、磷脂及中性类脂衍生物等。     

库斯塔克素（Kurstakins）—一类自Bt中分离出的具杀菌活性的新型脂肽

生物农药因其副作用小，对环境兼容性好而日益成为全球农药发展的一种趋势和方向。1992年“世界环境和发展大会”的第21条决议提出“到2000年要在全球范围内控制化学农药的销售和使用，生物农药的产量达到60％”。90年代以来，全世界化学农药的销售量下降，代之而起的是生物农药中的微生物农药。在微生物杀虫剂中，以苏云金芽孢村菌（简称Bt）制剂为代表。以伴孢晶体为主要成份的Bt制剂，具有高效、低毒、杀虫谱专一等优点，是目前世界上应用最广泛，商业开发最成功的生物农药，取得了显著的经济效益、社会效益和生态效益。在微生物杀菌剂中，井冈霉素是成功的代表。能够用于制备微生物杀菌剂的微生物类群，主要是链霉菌和放线菌，近几年也有芽孢村菌的报道。我国已有对黄瓜霜霉病具有较好防效的芽苞杆菌菌株和可防治多种水稻病害的芽孢杆菌的分泌物。和Bt能产生伴孢晶体相似，近来有文献报道，许多芽胞杆菌可以产生脂肽，并且这些肽还可作为每种芽孢杆菌的生化特征。目前，芽胞杆菌的脂肽在生物医学、农业中已有应用。     

芽孢杆菌产环脂肽类化合物结构与生物合成机制研究进展

芽孢杆菌产环脂肽类化合物结构多样,具有较强的抗菌活性,在农业和食品等应用广泛。近年来发现部分环脂肽具有拮抗人体病原菌及抗肿瘤等的药用价值。本文对芽孢杆菌产环脂肽类化合物的生物功能、结构和生物合成机制的研究进展做一总结。     

微生物起泡剂及其煤泥浮选应用的研究

分离一株能产生微生物起泡剂的假单胞菌(Pseudomonas sp.).考察了该菌株产生起泡剂的特性、起泡剂的成分以及起泡剂在煤泥浮选中的应用.结果表明,添加还原糖为20g/L,在第3d起泡剂达最高量.通过薄层层析分析,表明该起泡剂为脂肽类化合物,具有较高的起泡稳定性.通过微生物起泡剂进行煤泥浮选实验,其浮选效果与杂醇油相当.     

一种新型脂肽的分离纯化及其生物学活性

目的从表皮葡萄球菌发酵液中分离纯化脂肽粗提物,并分析其生物学活性。方法通过酸沉淀分离和有机溶剂抽提的方法,从表皮葡萄球菌1457发酵液中得到脂肽粗提物。利用排油圈试验和薄层色谱(TLC)分析脂肽粗提物的性质,HPLC分析其纯度。小鼠皮下注射脂肽粗提物后,再经皮肤感染金黄葡萄球菌,检测其对小鼠体内白细胞的影响及抑菌作用;实时定量PCR检测其对小鼠体内β防御素14(mBD14)表达的影响。结果所得脂肽粗提物F2的排油活性大于F1;TLC分析显示,F2中存在性质相近的脂肽类同系物,纯度>60%;脂肽粗提物能减缓小鼠因感染金黄葡萄球菌引起的急性炎症,降低由感染引起的白细胞增多,并通过上调mBD14的表达抑制细菌在皮肤内的增殖。结论已从表皮葡萄球菌发酵液中成功获得了具有生物学活性的新型脂肽粗提物。     

Engineered synthetic virus-like particles and their use in vaccine delivery

Engineered nanoparticles have been designed based on the self-assembling properties of synthetic coiled-coil lipopeptide building blocks. The presence of an isoleucine zipper within the lipopeptide together with the aggregating effects of an N-terminal lipid drives formation of 20-25 nm nanoparticles in solution. Biophysical studies support a model in which the lipid is buried in the centre of the nanoparticle, with 20-30 trimeric helical coiled-coil bundles radiating out into solution. A promiscuous T-helper epitope and a synthetic B-cell epitope mimetic derived from the circumsporozoite protein of Plasmodium falciparum have been linked to each lipopeptide chain, with the result that 60-90 copies of each antigen are displayed over the surface of the nanoparticle. These nanoparticles elicit strong humoral immune responses in mice and rabbits, including antibodies able to cross-react with the parasite, thereby, supporting the potential value of this delivery system in synthetic vaccine design.     

Design,Synthesis, and Evaluation of Lipopeptide Conjugates of Mercaptoundecahydrododecaborate for Boron Neutron Capture Therapy

We developed new ¹⁰B carriers for boron neutron capture therapy (BNCT) that can effectively transport and accumulate boron clusters into cells. These carriers consist of a lipopeptide, mercaptoundecahydrododecaborate (BSH), and a disulfide linker. The carriers were conceived according to the structure of pepducin, a membrane-penetrating lipopeptide targeting protease-activated receptor 1 (PAR1). To improve the membrane permeability of BSH, the structure was optimized using various lipopeptides possessing different peptides and lipid moieties. These synthesized lipopeptides were conjugated with BSH and evaluated for intracellular uptake using T98G glioblastoma cells. Among them, the most effectively incorporated and accumulated in the cells was compound 5 a , which contains a peptide of 13 residues derived from the intracellular third loop of PAR1 and a palmitoyl group. For further improvement of ¹⁰B accumulation in cells, the introduction of an amine linker was investigated; intracellular uptake similar to that of 5 a was observed for compound 14 , which has a piperazine linker. Both compounds 5 a and 14 showed a stronger radiosensitizing effect than BSH along on T98G cells under mixed-neutron beam irradiation. The results demonstrate that lipopeptide conjugation is effective for enhancing intracellular delivery and accumulation of BSH and improving the cytotoxic effect of BNCT.     

Biosurfactant-Assisted Bioremediation of Polycyclic Aromatic Hydrocarbons (PAHs) in Liquid Culture System and Substrate Interactions

A lipopeptide biosurfactant was produced by the bacterium Pseudomonas aeruginosa strain LBP9 isolated from petroleum-contaminated soil. Phenanthrene, fluoranthene, and pyrene were used as model polycyclic aromatic hydrocarbons (PAHs) to study the effect of the biosurfactant on the biodegradation of mixed and sole substrate PAHs, and examine substrate interactivity effects on their biodegradation in liquid culture. At 400 mg/L amendment of lipopeptide, the solubility of phenanthrene, fluoranthene, and pyrene were increased to 19, 33, and 45 times their aqueous solubility, respectively, and the extent of substrate utilization rate (q_max?) of PAHs was enhanced up to three-fold in the sole substrate studies in comparison to the unamended controls. In the ternary PAH mixture at total concentration of 300 mg/L, with equal parts of each PAH, 77%, 57%, and 33% degradation of phenanthrene, fluoranthene, and pyrene were observed, respectively, at 400 mg/L lipopeptide amendment on day 30 of incubation. Whereas in the sole substrate experiments at 300 mg/L concentration of each PAH and the same level of lipopeptide amendment more than 98% fluoranthene and 76% pyrene were degraded and phenanthrene removal was so rapid that at day 4 of incubation more than 80% was degraded. Biosurfactants at optimum amounts enhanced biodegradation of PAHs. Lipopeptide amendments of 200 mg/L and 400 mg/L were found out to be optimum amounts for statistically significant (p < 0.05) biodegradation of the PAHs in the experiments. However, despite biosurfactant-enhanced bioavailability of the PAHs, biodegradation rate was competitively inhibited in the multisubstrate microcosms.     

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.     

产脂肽生物表面活性剂细菌的筛选及培养基优化

利用变色圈法和噬油斑法从土壤样品中分离筛选出一株产生物表面活性剂的细菌菌株LB345,通过薄层层析(TLC)确定其所产生物表面活性剂为脂肽,并通过单因素实验及L9(34)正交实验对菌株的培养基配方进行了优化,确定优化培养基的组成(g/L):葡萄糖30,NaNO32,KH2PO410,Na2HPO410,FeSO42.5×10-4,MgSO4.7H2O 0.03,NaC l 5,CaC l20.4,酵母粉0.3,初始pH值5,培养温度37℃,发酵时间7 d。在上述条件下,菌株LB345的脂肽产量可达到0.7 g/L。     

Synthesis of enhanced biosurfactant by Bacillus subtilis MTCC 2423 at 45°C by foam fractionation

Production of a lipopeptide surfactant in a 6.5-L batch fermentor was carried out using Bacillus subtilis MTCC 2423 at 45°C. A good yield was obtained from sucrose (2%) substrate fermentation by continuous removal of the product by foam fractionation. The biosurfactant was recovered from collapsed foam by acid precipitation. The biosurfactant yield (4.5 g/L) was about 4.5 times higher than the yield (ca. 1 g/L) obtained by shake-flask fermentation. Surface activity of the collapsed foam was very high, and total surface activity was observed in the collapsed foam. The structural characterization of this biosurfactant produced at 45°C by the strain used in this study was recently reported. The biosurfactant was analyzed by thin-layer chromatography, infrared, ¹H nuclear magnetic resonance, and mass spectroscopy and was found to be identical to surfactin, a lipopeptide surfactant.     

达托霉素的作用机制和药物来源的研究进展

达托霉素是一种环脂肽类抗生素,对耐药性革兰氏阳性细菌具有强大杀灭作用。本文详细介绍了达托霉素的作用机制,总结了其药物来源,分别对达托霉素的各种合成方法——前体诱导法、生物合成、固液相合成法及其类似物的全固相合成法和化学酶法进行了概述和比较。