Condition Optimization of Lipopeptide Production by Bacillus natto NT-6 in Solid-State Fermentation with Box-Behnken Design

Solid-state fermentation has certain advantages in improving the yield of lipopetide, Box-Behnken Design（BBD） was adopted to optimize the producing condition of the antibacterial lipopetide produced by Bacillus natto in this article. The optimal solid state fermentation conditions were obtained： 10 g solid medium（7 g of wheat bran, 3 g of soybean meal） with appropriate inorganic salt（glucose 0.67%,sodium glutamate 0.64%,（NH4）2SO40.15%, K2HPO40.10%）; moisture content 123.78%; inoculation amount 10%; cultivation temperature 36.75 ℃ and cultivation time 72.4 h. The maximum production of lipopetide is 61.76 mg/gds under such conditions. This is the first report on the optimization of lipopeptide fermentation conditions in solid-state fermentation by wheat bran and soybean meal with Bacillus natto NT-6 strain, and will contribute to the development of lipopetide production.

Derringer desirability and kinetic plot LC-column comparison approach for MS-compatible lipopeptide analysis

Lipopeptides are currently re-emerging as an interesting subgroup in the peptide research field, having historical applications as antibacterial and antifungal agents and new potential applications as antiviral, antitumor, immune-modulating and cell-penetrating compounds. However, due to their specific structure, chromatographic analysis often requires special buffer systems or the use of trifluoroacetic acid, limiting mass spectrometry detection. Therefore, we used a traditional aqueous/acetonitrile based gradient system, containing 0.1% （m/v） formic acid, to separate four pharmaceutically relevant lipopeptides （polymyxin B1, caspofungin, daptomycin and gramicidin A1）, which were selected based upon hierarchical cluster analysis （HCA） and principal component analysis （PCA）.In total, the performance of four different C18 columns, including one UPLC column, were evaluated using two parallel approaches. First, a Derringer desirability function was used, whereby six single and multiple chromatographic response values were rescaled into one overall D-value per column. Using this approach, the YMC Pack Pro C18 column was ranked as the best column for general MS-compatible lipopeptide separation. Secondly, the kinetic plot approach was used to compare the different columns at different flow rate ranges. As the optimal kinetic column performance is obtained at its maximal pressure, the length elongation factor λ（Pmax/Pexp） was used to transform the obtained experimental data （retention times and peak capacities） and construct kinetic performance limit （KPL） curves, allowing a direct visual and unbiased comparison of the selected columns, whereby the YMC Triart C18 UPLC and ACE C18 columns performed as best. Finally, differences in column performance and the （dis）advantages of both approaches are discussed.

Lipopeptide Antibiotics Produced by the Engineered Strain Bacillus subtilis GEB3 and Detection of Its Bioactivity

MALDI-TOF-MS technology was used for identification of lipopeptide antibiotics producedby GEB3 strain, a derivative of Bacillus subtilis 168 which was transformed by lpaB3gene. The result showed GEB3 only produced lipopeptide antibiotic surfactin. The analysisby LC-MS demonstrated that GEB3 produced standard surfactin isoforms with side chainlengths of 13,14 and 15 carbon atoms. The bioactivity detection of surfactin indicatedthat the surfactin produced by GEB3 had inhibition effect on plant pathogens Rhizoctoniasolani and Pyricularia oryzae.

Safe antifungal lipopeptides derived from Bacillus marinus B-9987 against grey mold caused by Botrytis cinerea

Agricultural application studies, including field experiments and acute toxicity tests, were conducted for lipopeptides secreted by marine-derived Bacillus marinus B-9987. Benefiting from commercially available scaled-up lipopeptide purification, the sample of impurities（isolated from target lipopeptides）, raw extracted sample（purity： 9.08%）, partially purified sample（purity： 20.86%）, and highly purified sample（purity： 87.51%） were prepared from B. marinus B-9987 fermentation broth, and used in lab-scale antagonism tests, field experiments, swarming motility tests, and acute toxicity tests. Operations and conditions in field experiments were consistent with the Pesticide-Guidelines for the Field Efficacy Trials（GB/T 17980.28-2000）, and acute toxicity tests were executed according to Toxicological Test Methods of Pesticides for Registration（GB 15670-1995）. In agar diffusion tests in vitro and pot tests in vivo, all lipopeptide samples with different purities significantly inhibited Botrytis cinerea; meanwhile the sample of impurities isolated from target lipopeptides were not effective against B. cinerea. Results of lab-scale tests showed that the target lipopeptides were effective substances against B. cinerea. Thus, partially purified and raw extracted samples were used in field experiments instead of the highly purified sample for cost saving. In the field experiments against rose grey mold, biological control efficacy of 500 mg L–1 lipopeptides reached 67.53%, slightly lower than 74.05% reached by the agrochemical pyrimethanil. However, pyrimethanil severely suppressed B. marinus B-9987, whereas the lipopeptides promoted swarming motility and biocontrol efficacy of Bacillus biomass. Lipopeptides at 87.51% purity were tested for systemic acute toxicity and confirmed as low-toxicity substances. In conclusion, low-toxicity lipopeptides were potential alternatives to agrochemicals, and they also performed good promotion when combined with homologous biological control microorganism. There were 2 breakthroughs in this research：（1） marine-derived bacterial lipopeptides inhibited grey mold caused by B. cinerea in field experiments; and（2） purified bacterial lipopeptides（sample purity： 〉87.51%） were determined to be low-toxicity substances by systemic acute toxicity tests, satisfying the strict requirement of pesticide registration in China（required purity： 〉85%）. This study provides support for using extracellularBacillus-derived lipopeptides commercially similar to Bacillus-based biological control agents.

Combined Use of NMR, LC-ESI-MS and Antifungal Tests for Rapid Detection of Bioactive Lipopeptides Produced by Bacillus

The science and technology interact with the art in several ways. Biotechnological coupled with analytical approaches can play an important role in protecting and preserving cultural heritage for future generations. Many microorganisms influenced by environmental conditions are the main responsible for biological contamination in built heritage. Biocides based on chemical compounds have been used to mitigate this problem. Thus, it is vitally important to develop proper remediation actions based on environmentally innocuous alternative. Bacillus specie is emerging as an optimistic alternative for built heritage treatment due to their capacity to produce secondary metabolites with antagonistic activities against many fungal pathogens. Therefore, the intent of this work was to access a rapid evaluation of antifungal potential of bioactive metabolites produced by Bacillus strains and simultaneously their characterization using spectroscopic (NMR) and chromatographic techniques (LC-ESI-MS). The high antifungal activity obtained for Bacillus sp. active compounds produced in this study confirms the great potential to suppress biodeteriogenic fungi growth on historical artworks. Additionally, the proposed methodology allowed to access bioactive metabolites produced without need of the laborious total previous isolation and could be used as a viable alternative to be employed for screening and production of new green biocides.

Characterization on the Mean Molar Absorptivity of Amino Acids in Microbial Lipopeptides

The molar absorption coefficients of each of 14 kinds of amino acids were determined by the spectrophotometric method, and the mean molar absorption coefficients of 37 different mixtures of each with amino acid composition exactly equivalent to that of the peptide chain of the corresponding lipopeptide were determined based on calculation or experimental. The significance of the results is that the mean molar absorption coefficients strongly demonstrate the regular patterns, though different amino acids bear quite different molar absorption coefficients.

Lipopeptides for the Fragment-Based Pharmaceutics Design

This paper describes the synthesis of peptide fragments for use in a new type of combinatorial discovery technology, in which the building blocks are brought together by non-covalent interactions, rather than direct chemical bonding. The building blocks of interest—in this case different amino acids—are converted to amphiphiles by attachment to lipid tails. The amphiphiles, when mixed together in aqueous phase, are designed so that they aggregate spontaneously to form micelles. The building blocks form the headgroups of each of the amphiphiles, and these headgroups cover the surface of the micelle in a dynamic close-packed fluid mosaic array. These building blocks come together so closely that two- or three-dimensional structures are created on the surface of the micelles, and these can be screened in biological assays to find out which combination of building blocks is able to elicit a biological response. Lipopeptides consisting of two residues of lipoamino acid and other amino acids moieties have been designed, synthesized, characterized and the ability of these constructs to form supra-molecular assemblies is demonstrated.

Transcriptomics reveals substance biosynthesis and transport on membranes of Listeria monocytogenes affected by antimicrobial lipopeptide brevilaterin B

Listeria monocytogenes is a worrisome food-borne pathogen threatening global food safety.Our previous study proved that lipopeptide brevilaterin B showed efficient antibacterial activity against L.monocytogenes by interacting with the cell membrane.This research further explored the antibacterial mechanism of brevilaterin B against L.monocytogenes at the sub-minimum inhibition concentration via transcriptomic analysis.Brevilaterin B induced growth inhibition rather than direct membrane lysis in L.monocytogenes at the minimum inhibitory concentration.Transcriptomic analysis showed 1779 difference expressed genes,including 895 up-regulated and 884 down-regulated genes.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis indicated that brevilaterin B influenced multiple pathways of L.monocytogenes,including peptidoglycan biosynthesis,membrane transport(ATP-binding cassette transports,ion transport),cellular metabolism(amino acid and lipid metabolism),ATP synthesis,and activation of the stress response(quorum sensing and bacterial chemotaxis).In conclusion,brevilaterin B affects gene expression related to biosynthesis,transport and stress response pathways on the membrane of L.monocytogenes.The present work provides the first transcriptomic assessment of the antibacterial mechanism of lipopeptide brevilaterin B at the gene level.

Comparative Study of Disease Suppression on Various Host Plants by <i>Bacillus</i>Cyclic Lipopeptides

In biological controls using Bacillus spp., cyclic lipopeptides play a role as elicitors to induce disease resistance on various host plants. However, it is still unclear the specificity between cyclic lipopeptides and host plants to induce disease resistance. In this study, we aimed to clarify the specificity to induce disease resistance among cyclic lipopeptides on various host plants. Our data clearly showed both cyclic lipopeptides conferred disease suppression on most of host plants, but at different range of cyclic lipopeptide concentration. Our findings contribute to understanding the complex on the specificity of cyclic lipopeptide derived induced disease resistance.

Pseudomonas Cyclic Lipopeptide Medpeptin:Biosynthesis and Modulation of Plant Immunity

The multifunctional secondary metabolites known as cyclic lipopeptides(CLPs),which are produced by a large variety of bacteria,have become a key category of plant immunity elicitors.Pseudomonas-CLPs(PsCLPs)are extremely diverse in structure and biological activity.However,an understanding of CLP-plant structure–function interactions currently remains elusive.Here,we identify medpeptin,a novel CLP from Pseudomonas mediterranea that consists of 22 amino acids.Medpeptin is synthesized by a non-ribosomal peptide synthase(NRPS)gene cluster and regulated by a quorum-sensing system.Further research indicates that medpeptin does not exhibit antimicrobial activity;instead,it induces plant cell death immunity and confers resistance to bacterial infection.Comparative transcriptome analysis and virus-induced gene silencing(VIGS)reveal a set of immune signaling candidates involved in medpeptin perception.Silencing of a cell-wall leucine-rich repeat extensin protein(NbLRX3)or a receptor-like protein kinase(NbRLK25)—but not BAK1 or SGT1—compromises medpeptin-triggered cell death and resistance to pathogen infection in Nicotiana benthamiana.Our findings point to a noncanonical mechanism of CLP sensing and suggest perspectives for the development of plant disease resistance.

页岩油微生物采油菌株筛选与性能评价

从页岩油藏中筛选得到了一株产表面活性剂菌株Y2,利用16s rDNA基因测序对其进行鉴定;通过表/界面张力测试,优化菌株的培养条件并考察其在不同pH值、温度和盐浓度下的稳定性;通过FTIR和LC-MS分析表征菌株所产生物表面活性剂的理化性质。结果表明:菌株Y2(枯草芽孢杆菌,Bacillus subtilis)在以葡萄糖为碳源、硝酸铵为氮源的培养基中所产生物表面活性剂表面活性最优,菌株上清液的表面张力值27.61 mN/m,与页岩油JHW151和JHW07121之间的界面张力值分别为0.062 mN/m和0.047 mN/m。该菌株所产生物表面活性剂为C_(15)-Surfactin和C_(16)-Fengycin的脂肽混合物,其表面活性在温度为40~80℃和pH值为1~11范围内稳定性较好,但随着NaCl浓度的增加界面张力值变小。可见,Y2菌株具有较好的表面活性,能够有效降低油/水界面张力从而提高页岩油采收率,为吉木萨尔页岩油微生物驱的高效开发提供了一项潜在可行的技术路线。

Surfactin的结构、生物合成及其在生物防治中的作用

Surfactin是由多种芽孢杆菌产生的一种脂肽,其由一个环七肽头基通过内脂键与链长12-17个碳原子的β-羟基脂肪酸连接组成,是一种非常有效的生物表面活性剂,并具有重要的生物学功能。本文介绍了surfactin家族的结构和生物合成模式,surfactin是由非核糖体肽合成酶催化合成,这种机制赋予了surfactin家族成员的结构多样性;综述了surfactin在植物病害生防中的作用及机制。已有的研究表明surfactin在生物防治中的作用机制主要有以下4种方式:(1)损伤病原菌细胞膜,引起细胞膜裂解或渗透压失衡;(2)抑制病原体繁殖;(3)诱导植株系统抗性;(4)促进生防菌株的定殖或生物膜的形成。进一步总结了利用基因工程技术研究surfactin的最新进展,以指导surfactin的生物合成及其新衍生物开发。Surfactin的高度结构多样性,使其具有丰富的物理化学特性,这些特性可以与多种生物活性联系在一起,将在不同的领域有更广泛应用。随着对surfactin生物合成研究的日益深入,将会有更多高性能和广阔应用前景的新型脂肽被研发,这为surfactin的进一步研究和生防应用提供依据。

拮抗黄曲霉大花杓兰内生细菌的筛选及抑菌研究

为获得对黄曲霉菌丝生长具有良好抑菌活性的细菌资源,该研究以31株大花杓兰内生细菌为对象,通过平板对峙法和菌丝生长速率法筛选拮抗黄曲霉的内生细菌;菌丝生长速率法测定无菌发酵液对黄曲霉抑菌活性的稳定性;PCR扩增芽孢杆菌脂肽合成酶基因和多聚酮合酶基因;酸沉醇提制备芽孢杆菌脂肽粗提物,牛津杯法评估其对黄曲霉的抑菌活性。结果显示,3株大花杓兰内生芽孢杆菌(CmR-1n、CmR-3a、CmR-4b)对黄曲霉有较好抑菌活性;CmR-1n对黄曲霉的抑菌效果最好,平板拮抗率为57.88%,而CmR-1n无菌发酵液对黄曲霉的抑菌率达63.31%;芽孢杆菌CmR-1n无菌发酵液具有较好的耐热性、耐酸碱性、抗紫外线性和贮藏稳定性;CmR-1n基因组含有表面活性素基因Srf、伊枯草菌素基因Itu和丰原素基因(fenB和fenD),且体外抑菌实验证实CmR-1n脂肽粗提物甲醇液对黄曲霉菌丝生长的抑制率达62.58%。推测芽孢杆菌CmR-1n合成的脂肽可能是抑制黄曲霉的主要活性物质,使其在黄曲霉防治领域具有一定的应用潜力。

贝莱斯芽孢杆菌Vel-HNGD-F2产抗菌物质发酵条件优化及抗菌特性研究

从猪肠道微生物中筛选到的贝莱斯芽孢杆菌Vel-HNGD-F2对禾谷镰刀菌有良好的抑菌效果,有望用于禾谷镰刀菌引起的作物病害防治。为进一步提高菌株Vel-HNGD-F2的抗菌物质产量,采用响应面法对其发酵条件进行优化;通过酸沉淀法对菌株Vel-HNGD-F2的脂肽类物质进行粗提并检测抑菌活性,研究粗提物的稳定性;用已知的5种编码脂肽类抗生素的基因的特异性引物进行PCR扩增并测序分析;通过UPLC-Q-TOF-MS检测技术对脂肽粗提物的成分进行分析。结果表明:菌株Vel-HNGD-F2的最佳发酵条件为发酵温度36.49℃、发酵液初始pH 7.14、接种量3.13%,预测发酵上清液抑菌率为58.71%,实际抑菌率为58.49%;粗提物对禾谷镰刀菌有抑菌作用且具有良好的耐热性并对紫外照射不敏感;对PCR扩增产物测序结果经NCBI的在线BLAST比对,表明该菌含有与bmyB、fenD、ituC、srfAA和bacA同源的基因,推测菌株Vel-HNGD-F2可能分泌这5种脂肽;UPLC-Q-TOF-MS结果显示抗菌物质为包含surfactin、iturin和bacillomycin的混合物。菌株Vel-HNGD-F2能产生多种脂肽类物质,对禾谷镰刀菌具有较好的防治作用,具有生物防治真菌病原菌的应用潜力。

枯草芽孢杆菌抗菌脂肽的重组表达及应用研究进展

为了解决对人类健康和粮食安全构成重大风险的抗生素耐药性威胁,开发新型抗菌药物势在必行。枯草芽孢杆菌所产的抗菌脂肽不易使细菌产生广泛的耐药性且无任何副作用,被认为是最具潜力的抗菌剂之一。但是,枯草芽孢杆菌抗菌脂肽生产成本高和生产效率低的问题严重限制了其在食品、医药、环境等工农业领域的应用,因此提高抗菌脂肽产量显得尤为重要。近几十年来,随着生物技术的快速发展,利用基因工程和优化发酵策略来生产高产量的抗菌脂肽可以克服上述问题。本文从枯草芽孢杆菌所产脂肽的结构和功能特性出发,主要从高产抗菌脂肽技术、构效关系以及应用进行综述,特别是基因工程方法提高脂肽产量的研究进展,为枯草芽孢杆菌高产抗菌脂肽的进一步研究提供参考。

芽孢杆菌脂肽对金黄色葡萄球菌的抑制机理

为了减少因滥用抗生素而导致的金黄色葡萄球菌耐药性的增长,本研究旨在寻找天然、安全的抑菌物质替代传统抗生素治疗金黄色葡萄球菌感染。研究选取贝莱斯芽孢杆菌SN-20、解淀粉芽孢杆菌SN-31、解淀粉芽孢杆菌SN-34、解淀粉芽孢杆菌SN-36、枯草芽孢杆菌SN-43、解淀粉芽孢杆菌SN-46共6株芽孢杆菌进行薄层分析、脂肽稳定性测试以及脂肽抑菌机制的测定。结果表明:6株芽孢杆菌可产生表面活性素、芬原素和伊枯草菌素等脂肽,其中贝莱斯芽孢杆菌SN-20和解淀粉芽孢杆菌SN-46脂肽粗提物对金黄色葡萄球菌表现出显著的抑制效果,抑菌圈直径均达到12.5 mm以上,最小抑菌浓度(MIC)分别为1.25 mg/mL和2.5 mg/mL。2株芽孢杆菌产生的脂肽分别在pH值为3和11、温度100℃以及蛋白酶K处理下仍能保持抑菌效果,表明脂肽具有良好且稳定的抑菌特性。进一步分析发现,脂肽通过破坏细胞膜结构、增加细胞膜通透性、抑制蛋白质合成等多种机制对金黄色葡萄球菌产生抑制作用,且这种多机制的作用不易产生耐药性。本研究表明,芽孢杆菌产生的脂肽具有良好的应用前景,有望开发为新的抗金黄色葡萄球菌药物。

摩氏假单胞菌环脂肽合成基因簇xtlABC的功能研究

摩氏假单胞菌Pseudomonas mosselii Pt A1是对多株青枯菌均有良好抑制作用的生防菌,基因组中含有完整的环脂肽合成基因簇xtlABC。为了探明摩氏假单胞菌PtA1中xtl ABC基因簇的功能,本研究利用同源重组技术获得缺失突变体ΔxtlA、ΔxtlBC和Δxtl ABC,通过Southern blot验证突变体正确后,分析其对菌株生长速率、游动性、生物膜及生防相关性状等表型的影响。研究结果显示,与野生型菌株Pt A1相比,突变体ΔxtlA、ΔxtlBC和ΔxtlABC在LB培养基中的生长速度变慢,在游动培养基上的迁移直径分别减少了12.6、12.5和13.5mm,生物膜形成量分别降低了30.41%、29.16%和30.70%,对4种青枯菌的抑菌圈直径显著减小。盆栽试验表明,接种青枯菌GMI1000后4d,处理组PtA1+GMI1000、ΔxtlA+GMI1000、ΔxtlBC+GMI1000和ΔxtlABC+GMI1000对番茄青枯病的防效分别为44.93%、9.49%、10.46%和7.66%,第10 d的防效分别为42.43%、19.56%、31.40%和24.79%,处理组PtA1+GMI1000防治效果最好,与xtlABC突变体处理组差异显著。综合分析表明xtlABC基因簇影响菌株自身的生长及生防相关性状,该基因及其合成的次生代谢产物在抑制青枯菌中起重要作用。

以新型脂肽为佐剂的LP-LNP构建及其对mRNA疫苗的增效作用

目的构建以新型脂肽为佐剂的递送系统脂肽-脂质纳米颗粒(lipopeptide-lipid nanoparticle,LP-LNP),初步探究其对mRNA疫苗的增效作用。方法设计并合成2种新型脂肽SS-10和SQ18,微流控技术将编码增强型绿色荧光蛋白(enhanced green fluorescent protein,eGFP)、萤火虫荧光素酶(firefly luciferase,F-luc)和卵清白蛋白(ovalbumin,OVA)的mRNA包载到LP-LNP中,构建以新型脂肽为佐剂的mRNA递送系统;利用动态光散射法表征LP-LNP的粒径、多分散系数;利用HEK-Blue TM mTLR2报告细胞检测其Toll样受体2(Toll-like receptors 2,TLR2)的激活作用,筛选最优脂肽掺入比;将优选的LP-LNP-eGFP-mRNA转染至HEK293T细胞,荧光显微镜观察eGFP的表达;利用活体成像技术考察LP-LNP-F-luc-mRNA在小鼠体内的表达水平;流式细胞术评价LP-LNP-OVA-mRNA免疫小鼠后诱导引流淋巴结中树突状细胞(dendritic cells,DCs)成熟水平以及交叉递呈抗原的能力。结果脂肽SQ18和SS-10分别以0.50%、0.75%的摩尔比掺入后,得到的LP-LNP平均粒径分别为127和121 nm,平均多分散系数分别为0.11和0.08,包封率均在90%以上,且体外安全性好;该配方条件下激活TLR2的能力显著强于阳性对照Pam 2 CSK 4(P<0.01);优选的LP-LNP均可以实现有效的体外转染,其中SQ18以0.50%掺入制备的LP-LNP体内转染效果显著优于传统LNP(P<0.01),且可以显著促进引流淋巴结DCs的成熟以及抗原的交叉递呈(P<0.05)。结论以新型脂肽为佐剂的LP-LNP可以增强mRNA的递送能力,进一步提高mRNA疫苗的免疫效果。

高产抗菌脂肽芽孢杆菌的分离鉴定筛选及发酵工艺优化

为了筛选出高产抗菌脂肽的芽孢杆菌并确定其最佳发酵工艺条件,研究从传统发酵豆酱中分离和鉴定产抗菌脂肽芽孢杆菌菌株,通过正交试验研究了发酵接种量、发酵填液量、发酵时间、发酵温度等发酵条件对芽孢杆菌脂肽产量的影响。结果表明,从9份东北传统发酵豆酱中分离筛选得到27株芽孢杆菌,经16S rDNA鉴定,其中6株芽孢杆菌具有合成脂肽的基因sfp、fenB和ituA。通过单位菌体脂肽产量和抑菌效果测定发现,贝莱斯芽孢杆菌SN-20和解淀粉芽孢杆菌SN-46表现优异,单位菌体脂肽产量达106和72 mg,且对革兰氏阳性和阴性指示菌均有较强的抑菌效果。正交试验发现贝莱斯芽孢杆菌SN-20最佳发酵工艺为:接种量3%,发酵填液量20%,发酵时间36 h,发酵温度32℃;枯草芽孢杆菌SN-46最佳发酵工艺为:接种量2%,发酵填液量40%,发酵时间24 h,发酵温度32℃。在此条件下发酵的两株芽孢杆菌单位菌体脂肽产量优化前为106.11和76.23 mg/g,优化后分别提高了21.85%和23.84%。研究结果有效地增加了芽孢杆菌抗菌脂肽的产量。

脂肽类生物表面活性剂用于提高原油采收率的研究进展

生物表面活性剂表面活性强,乳化性能好,抗菌抗氧化活性强,稳定性高,且生物选择性好,环境友好性强。其中,脂肽类生物表面活性剂性能突出,是三次采油中化学表面活性剂的良好替代品。根据肽链氨基酸是否连接成环,可将脂肽类生物表面活性剂分为环状脂肽和线形脂肽。亲水肽链不同种类氨基酸与排列顺序、疏水碳链长度及其支链位置不同,形成的脂肽结构与生物活性不同。脂肽类生物表面活性剂提高原油采收率的机理为:高效降低油水界面张力、促进原油乳化形成大尺寸胶束,改变储层岩石润湿性、降低水相相对渗透率等。脂肽类生物表面活性剂用于原油开采的室内实验和矿场试验结果表明,脂肽类生物驱油体系在获得与化学驱相当的提高采收率效果的同时可以有效降低驱油剂成本,证实了其适用于提高原油采收率的可行性。但脂肽在上游合成高产途径、下游低成本提纯工艺以及实际油藏中的地层适应性尚不明确,限制了脂肽类生物表面活性剂在油田的商业化推广。