槐糖脂的生物合成及最新应用

生物表面活性剂与化学表面活性剂相比,具有显著的优势:无毒、可生物降解、生态安全以及高表面活性等优点。槐糖脂作为一种生物表面活性剂,广泛的应用于食品、医药、日化及环境保护等领域,有逐渐取代化学表面活性剂的趋势。主要介绍了产槐糖脂的微生物和槐糖脂的生物合成过程,以及槐糖脂在纳米技术中的应用,具有广泛的应用前景。     

槐糖脂的研究进展

槐糖脂作为化学法生产的表面活性剂的良好替代品,其使用范围越来越广泛,因此对其的研究也日益增多。合成槐糖脂的方法有很多种,近年来通过发酵法生产槐糖脂的研究备受关注。本文就其产生菌、生产、应用及修饰的研究进展作一综述。     

槐糖脂与聚丙烯酰胺的相互作用

通过表面张力和表观黏度的测定,研究了槐糖脂与聚丙烯酰胺(PAM)的相互作用。结果表明,加入PAM,槐糖脂溶液的表面张力略有升高,临界胶束浓度(CMC)由约30 mg/L升高为约40 mg/L,但槐糖脂/PAM混合溶液的表面张力主要受槐糖脂浓度的影响。温度升高,混合溶液的表面张力略有降低,CMC保持不变;加入氯化钠,混合溶液的表面张力略有降低。由于槐糖脂与PAM的"疏水微区"相互作用形成混合胶束,加入槐糖脂,PAM溶液的表观黏度出现不同程度的升高,当槐糖脂浓度为30 mg/L时,PAM溶液的表观黏度最高。槐糖脂与聚丙烯酰胺复配在降低表面张力的同时能提高体系的表观黏度,适用于三次采油技术。     

槐糖脂与聚丙烯酰胺的相互作用

通过表面张力和表观黏度的测定,研究了槐糖脂与聚丙烯酰胺(PAM)的相互作用。结果表明,加入PAM,槐糖脂溶液的表面张力略有升高,临界胶束浓度(CMC)由约30 mg/L升高为约40 mg/L,但槐糖脂/PAM混合溶液的表面张力主要受槐糖脂浓度的影响。温度升高,混合溶液的表面张力略有降低,CMC保持不变;加入氯化钠,混合溶液的表面张力略有降低。由于槐糖脂与PAM的"疏水微区"相互作用形成混合胶束,加入槐糖脂,PAM溶液的表观黏度出现不同程度的升高,当槐糖脂浓度为30 mg/L时,PAM溶液的表观黏度最高。槐糖脂与聚丙烯酰胺复配在降低表面张力的同时能提高体系的表观黏度,适用于三次采油技术。     

发酵液中鼠李糖脂的活性炭吸附-酸沉淀分离

采用活性炭吸附-酸沉淀法从铜绿假单胞菌发酵液中提取鼠李糖脂。探讨了活性炭吸附鼠李糖脂的热、动力学规律,研究了p H值对活性炭吸附鼠李糖脂的影响及洗脱剂与洗脱时间的选择。结果表明:p H 7.0、吸附温度40—80℃时果壳活性炭的吸附平衡时间为60—140 min,80℃得到最大吸附量40.2 mg/g;酸沉淀能显著提高吸附量,p H 2.0时,果壳活性炭对鼠李糖脂的平衡吸附量提高至120.6 mg/g,一次吸附回收率达76.1%。适宜的洗脱剂为体积分数95%乙醇,洗脱时间为2 h,鼠李糖脂一次洗脱回收率为30.2%。该方法避免了有毒挥发性有机溶剂的使用,是一种经济环保的鼠李糖脂分离提取工艺。     

小麦秸秆的预处理对球拟假丝酵母产槐糖脂的影响

考察小麦秸秆的预处理方式对球拟假丝酵母(Starmerella bombicola)利用其糖化液发酵产槐糖脂(SLs)的影响，并对发酵进行优化。分别选择稀酸预处理(DAP)、NaOH预处理(SHP)和SO3微热爆预处理(STMEP)对小麦秸秆进行预处理，使用纤维素酶酶解糖化后将糖化液用于SLs的发酵，采用补加葡萄糖和活性炭脱毒的方法提高SLs的产量。结果显示，SHP最利于小麦秸秆的酶解糖化，所得糖化液中葡萄糖含量达61.30 g/L，其次为STMEP和DAP，葡萄糖含量分别为48.33 g/L和40.00 g/L。STMEP糖化液中抑制物的总含量最低，其次为SHP和DAP。S. bombicola可以直接利用上述糖化液发酵产SLs，但发酵特性有所不同。SHP和STMEP糖化液更利于酸型槐糖脂(ASL)的积累，相比于化学合成培养基，其产量分别提高了74.27%和92.33%，达到100.45 g/L和110.86 g/L。补加葡萄糖和活性炭脱毒可以进一步提高SLs的产量。对于SHP糖化液，补加葡萄糖及其与活性炭脱毒的联合可将ASL的产量进一步提高至124.49 g/L；对于STMEP糖化液，则可将内酯型槐糖脂(LSL)的产量进一步提高至32.02 g/L，与化学合成培养基的LSL发酵水平相当。因此，小麦秸秆具备发酵产SLs的潜力，且不同预处理方式及发酵方式可用于获得不同类型的SLs，本研究有助于降低SLs的生产成本并拓展其应用领域。     

应用煎炸废油发酵制备槐糖脂生物表面活性剂

应用正交实验,优化了假丝酵母菌O-13-1以煎炸废油为油溶性碳源发酵槐糖脂的条件,并应用高效液相色谱-高分辨串联质谱（HPLC-MS/MS）鉴定了所产槐糖脂同系物的组成及结构。结果表明,经正交实验优化的O-13-1菌株以煎炸废油为底物制备槐糖脂的摇瓶发酵条件为：摇床转速200r/min,双碳源添加量均为90g/L,温度为25℃,接种量为体积分数12%,槐糖脂产量在菌株稳定生长期的后期即204h时达到最大,为57.64g/L;O-13-1菌株以煎炸废油为底物所合成槐糖脂由9种乙酰基取代的内酯型和酸型槐糖脂同系物构成,内酯型槐糖脂同系物所占质量分数达76%。基于摇瓶得到的以煎炸废油为油溶性碳源的优化发酵条件,O-13-1菌株在5L自动发酵罐中转速500r/min时发酵合成槐糖脂产量可达163.28g/L。以煎炸废油为碳源发酵槐糖脂的原料成本较普通大豆油降低18%,在有效降低槐糖脂生产成本的同时,实现了煎炸废油的资源化利用。     

应用煎炸废油发酵制备槐糖脂生物表面活性剂

应用正交实验,优化了假丝酵母菌O-13-1以煎炸废油为油溶性碳源发酵制备槐糖脂的条件,并应用高效液相色谱-高分辨串联质谱(HPLC-MS/MS)鉴定了所产槐糖脂同系物的组成及结构。结果表明,经正交实验优化的O-13-1菌株以煎炸废油为底物制备槐糖脂的摇瓶发酵条件为:摇床转速200 r/min,双碳源质量浓度均为90 g/L,温度为25℃,接种量为体积分数12%。在此条件下,槐糖脂产量达到最大,为73.26 g/L;O-13-1菌株以煎炸废油为底物所合成槐糖脂由9种乙酰基取代的内酯型和酸型槐糖脂同系物构成,内酯型槐糖脂同系物所占质量分数达76%。基于摇瓶得到的以煎炸废油为油溶性碳源的优化发酵条件,O-13-1菌株在5 L自动发酵罐中转速500 r/min时发酵合成槐糖脂产量可达163.28 g/L。以煎炸废油为碳源发酵槐糖脂的原料成本较普通大豆油降低18%,在有效降低槐糖脂生产成本的同时,实现了煎炸废油的资源化利用。     

槐糖脂为助剂的多杀霉素悬浮剂的润湿分散剂筛选

采用湿法研磨工艺,通过对比实验确定槐糖脂对多杀霉素悬浮剂的助分散性。在此基础上,通过不断提高多杀霉素的质量分数,以粒径和稳定性为考察指标筛选适用于不同质量分数多杀霉素悬浮剂的润湿分散剂。结果表明,槐糖脂具有降低多杀霉素悬浮剂粒径,提高悬浮剂稳定性的作用,适合用作多杀霉素悬浮剂的助分散剂。以槐糖脂为助分散剂,Well-301、Well-303和7227-A分别适合用作多杀霉素质量分数不大于5%、7.5%和10%悬浮剂的单一分散剂。生物表面活性剂有望部分替代化学表面活性剂应用于农药悬浮剂中。     

高黏发酵液中γ-聚谷氨酸的分离纯化工艺生物化工

γ-聚谷氨酸(γ-PGA)是由多种杆菌产生的一种胞外多肽,发酵生产时由于黏度高导致菌液分离困难。文中优化了发酵液微滤除菌、超滤浓缩和醇析干燥的工艺参数。综合考虑渗透通量、压差和除菌率等参数,确定微滤最佳操作温度为40℃,最佳操作压差0.3-0.4 MPa,最佳稀释度为V(发酵液)∶V(水)=1∶2,除菌率最高可达92.47%,在此条件下可以保持较高的渗透通量和较快的浓缩液循环流速,使微滤过程更为高效,同时不会因压力过高而造成微滤膜过早堵塞。通过优化,选择超滤最佳的浓缩比为5,此时渗透通量为31.8 L/(m2·h),产物回收率为81.6%。对pH=3—10共9个梯度进行了考察,比较在不同pH值条件下醇析操作纯化γ-PGA的粗产量,最优pH=7可达到最好的沉淀效果。这一优化分离工艺具有应用于γ-聚谷氨酸生产的潜力。     

发酵液絮凝过程絮凝体微尺度与分离性能

为探索发酵液絮凝分离过程规律以提高分离效率,本文在微观层面上研究发酵液絮凝过程中的剪切力、絮凝体尺度对絮凝体过滤分离效果的影响。以小诺霉素发酵液为研究对象,在絮凝过程中改变絮凝体所受的剪切力,使用激光粒度分析仪在0.02～2000 μm尺度内测定不同剪切力下絮凝体的粒度及粒度分布,并测定絮凝体的过滤速率及沉降速率。实验结果显示：絮凝体的粒度随剪切力的增大而减小,絮凝体的粒度分布宽度随剪切力的增大而增大;絮凝体的沉降分离速率随絮凝体粒度的增大而增大;在适度的剪切力下絮凝体有一适度的粒度及粒度分布宽度和较大的密实度,此时絮凝体的过滤分离速率有一最大值。实验结果表明：絮凝过程中的剪切力显著影响絮凝体的粒度、粒度分布和密实度,从而显著影响絮凝体的过滤速率及沉降速率。     

Clarification of succinic acid fermentation broth by ultrafiltration in succinic acid bio–refinery

BACKGROUND: Succinic acid is an important precursor chemical for the synthesis of high value‐added products. In this work, ultrafiltration was first investigated to clarify succinic acid fermentation broth by integrating fermentation and separation and removal processes of the product in situ. Four different ultrafiltration membranes (PES 100 kDa, PES 30 kDa, PES 10 kDa and RC 10 kDa) were used in this work. RESULTS: Results indicate that ultrafiltration is feasible for clarifying succinic acid fermentation broth. Almost all the microorganism cells (99.6%) were removed from the fermentation broth. Proteins were also removed effectively by all the membranes studied. The removal rate was 79.86% for PES 100 kDa, 86.43% for PES 30 kDa, 86.83% for PES 10 kDa, and 80.06% for the RC 10 kDa. After ultrafiltration, a clearer permeate was obtained compared with that from centrifugation. CONCLUSION: Membranes operating at high flux are always susceptible to rapid fouling. Compared with molecular weight cut‐offs (MWCO), membrane material has a significant influence on the flux. Membrane flux measured in this study shows industrial potential of this technology in treatment of succinic acid fermentation broth. © 2012 Society of Chemical Industry     

给水处理工艺系统分析与优化

通过对华东地区原水水质分析,根据不同的污染程度将该地区原水分为三类.通过处理单体和总体工艺的模型分析与优化,确定对应的三类推荐处理工艺,并应用系统分析与优化方法进行效果分析.     

Purification of lactic acid from fermentation broth by spherical anion exchange polymer

Lactic acid, as a versatile chemical, was purified from fermentation broth by solid phase extraction with a spherical porous poly(4‐vinylpyridine). Adsorption isotherm of lactic acid on poly(4‐vinylpyridine) was first investigated with model solutions. The factors which affect the performance of separation and purification were then investigated. The obtained results indicate that the sorbent had a high adsorption capability of lactic acid, of which the maximum adsorbed lactic acid was 180.0 mg g⁻¹. Under the optimal condition the lactic acid was purified from fermentation broth by solid phase extraction with the purity of 88% and recovery yield of 95%. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Head group-modified sophorolipids: Synthesis of new cationic, zwitterionic, and anionic surfactants

Amino acid-glycolipid conjugates were prepared using carbodiimide-mediated coupling methods. The amino acid units were multifunctional and possessed a para-aminobenzoic acid linker. The glycolipid used was a stearic sophoroside. The aim of preparing these modified sophorolipids was to increase their water solubility as well as to introduce sites at the polar head groups that permitted further chemical derivatization. After acidolytic or hydrogenolytic deprotection of the amino acid N-terminus or side chain, water-soluble compounds were obtained that displayed good surfactant properties. Critical micelle concentration values were clustered in the range of high 10⁻⁶ to low 10⁻⁵ M, and minimum surface tension values were below 40 mN m⁻¹. Two of the compounds represented more complicated structural classes, namely, gemini and bolaform surfactants.     

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.     

西梭霉素发酵液预处理工艺特性

应用正交试验研究了絮凝剂类型、质量浓度、发酵液pH值、动态过滤等因素对西梭霉素发酵液预处理效果的影响,获得适宜的预处理工艺条件。实验结果表明阴离子型聚丙烯酰胺A8025质量浓度为0.14g/L、pH=9—10时絮凝效果较好,经絮凝处理后的发酵液死端过滤常数比未经絮凝处理的发酵液死端过滤常数提高27.8倍,在此基础上若采用动态过滤不仅能进一步提高过滤速率,而且在过滤过程中西梭霉素的损失减少了7.9%。     

Cell recycle and broth reuse fermentation with cross-flow filtration and ion-exchange resin

A novel integrated fermentation system in which cross-flow filtration was coupled to an anion-exchange resin column was developed to achieve biomass recycle and broth reuse for lactic acid fermentation. An anion-exchange resin column was employed to recover lactic acid from the spent broth. The effluent was diluted with fresh medium, supplemented with glucose and nutrients. Spent broth was reused for three consecutive biomass recycle fermentations with no significant decrease in fermentation performance. The fermentation system enabled simultaneously high productivity of lactic acid (average value 7·75 g dm⁻³ h⁻¹ and total amount of lactic acid produced 85·21 g dm⁻³ after 11 h fermentation), high productivity of cells (average value 2·00 g dm⁻³ h⁻¹) and efficient utilization of medium (about 75% of the spent broth was reutilized). The system described may be applied to other organic fermentations subject to end-product inhibition.     

超滤技术在IgY分离中的应用

近年来,超滤技术在IgY分离纯化方面取得了一些新成果,有着广阔的应用前景。介绍了超滤分离的原理,以及在IgY分离中的主要应用。     

珍贵橙色束丝放线菌发酵产安丝菌素P-3的分离纯化工艺优化

安丝菌素是从珍贵橙色束丝放线菌的发酵液中分离出来的苯安莎类抗生素,具有显著的抗肿瘤活性。常采用乙酸乙酯对发酵液进行分离萃取,然而其发酵液成分复杂,除菌丝体外还含有许多杂蛋白质及易溶于有机溶剂的色素,这对后续提取和精制有很大的影响,影响产品质量和回收率。本文通过对AP-3发酵液进行预处理,将AP-3发酵液调整pH至3后,用10g/L硅藻土辅助抽滤;收集滤液,添加20g/L活性炭于60℃吸附2h,然后用洗脱液乙酸乙酯对活性炭进行脱附处理,2h后达到动态洗脱平衡,对洗脱液采用中性氧化铝柱层析,以乙酸乙酯和石油醚作为洗脱剂进行梯度洗脱,最终获得AP-3纯度86.15%,经重结晶后得到AP-3纯品,经过HPLC检测AP-3纯度达95%。