有机介质中包衣菌体催化合成c9,t11-共轭亚油酸

以3种脂肪醇(正辛醇、月桂醇和肉豆蔻醇)为原料,合成得到3种谷氨酸二烷基酯核糖醇(2C8GE、2C12GE和2C14GE),比较了不同谷氨酸二烷基酯核糖醇及其浓度和所用溶剂种类,以及缓冲液pH、包衣时间、温度和干燥方式对包衣Lactobacillus helveticus L7菌体酶活的影响。确定了制备包衣菌体的条件为:表面活性剂为谷氨酸双十二烷基酯核糖醇(2C12GE),将其配制成质量分数为1.0%的丙酮溶液;菌体用pH 5.8的磷酸盐缓冲液重悬;在4℃下处理4h经冷冻干燥而成包衣菌体。亚油酸经包衣菌体催化18h后,其转化率为95.3%,c9,t11-共轭亚油酸的产量为1906 mg/L。包衣菌体在有机溶剂中重复使用5次仍然具有较高的催化活性。在以亚油酸为底物时,包衣菌体中亚油酸异构酶的米氏常数(Km)为35.7 mmol/L,最大反应速度(Vmax)为5.6 mmol/h。经包衣处理后,菌体中亚油酸异构酶和底物的亲和力有所降低。     

重组人骨形态发生蛋白-7工程菌的高密度发酵

目的建立重组人骨形态发生蛋白-7(rhBMP-7)工程菌的高密度发酵工艺。方法采用摇瓶及发酵罐培养工程菌BL21/pBV221-rhBMP-7,观察不同培养基、乙酸浓度、pH值、诱导时间等对工程菌菌体生长及目的蛋白表达的影响。在优化的发酵条件下培养工程菌,当菌体A600值达100时,42℃升温诱导,并对表达产物进行纯化。结果发酵培养基与LB培养基培养的工程菌目的蛋白的表达量无明显差异;乙酸可明显抑制菌体生长及目的蛋白表达;最适于菌体生长和目的蛋白表达的pH值分别为6.8和7.6;最佳诱导时间为3h。以优化的发酵条件培养的工程菌诱导3h后,目的蛋白的表达量可达菌体总蛋白的34.9%,最终菌体A600值可达139.5;经纯化的目的蛋白纯度可达95%以上。结论已初步建立了rhBMP-7工程菌的高密度发酵工艺。     

预防O139霍乱B亚单位/全菌体口服疫苗的研究

目的 研制预防O139霍乱的B亚单位／全菌体口服疫苗。方法 应用重组霍乱毒素B亚单位及福尔马林灭活的O139霍乱弧菌全菌体,构建成B亚单位／全菌体疫苗,并进行安全性及免疫原性检测。结果 经连续3天大剂量灌喂小鼠后,未见体重下降、发病或死亡现象。全部小鼠均健康活存。以腹腔或口服免疫小鼠后,均能产生外周血或肠道局部高滴度的特异抗体。免疫小鼠对O139活菌攻击有良好的保护作用。结论B亚单位／全菌体口服疫苗在小鼠试验中安全性及免疫原性良好。     

重组类人胶原蛋白的分离纯化

目的 建立重组类人胶原蛋白分离及纯化工艺。方法 将工程菌株E.coli BL21 3.1在L1523型12.8L自控发酵罐中培养14h,发酵菌体经超声破碎、硫酸铵沉淀后,依次经DEAE-52和Sephadex G-100柱层析分离纯化。结果 发酵菌体干重达到71g/L,表达量为菌体蛋白量的29.4％,最终产物纯度达98％,回收率为80.5％,纯化倍数为3.4。结论 纯化的类人胶原蛋白达电泳纯,相对分子质量为90 000,N端序列为NH_2-H-D-P-V-V-L-Q-R-R-D-W-E-N-P-G,均与其因序列设计一致。     

酿酒酵母对铜离子的吸附

采用啤酒生产过程中产生的废酿酒酵母,对影响菌体对Ｃｕ＾２＋吸附的主要因素进行了探讨,对经不同方法处理的菌体进行了Ｃｕ＾２＋吸附性能的比较分析,并得出了吸附等温曲线,研究了吸附后菌体的法脱和再生。     

枯草芽孢杆菌E79分批发酵动力学

基于Logistic和Leudeking-Piret方程,根据分批发酵过程中菌体生长、产物积累、总糖消耗、还原糖消耗及反应体系pH值的变化规律构建枯草芽孢杆菌E79发酵过程中菌体细胞生长、产物合成及基质消耗的动力学模型,应用SPSS11.5软件对数据进行计算与分析,Oirgin 7.5软件经非线性拟合与优化,获得了最佳...     

二次正交旋转组合设计优化猪源罗伊乳杆菌冷冻干燥保护剂

目的优化猪源罗伊乳杆菌冷冻干燥的保护剂配方,提高冻干后的菌体存活率。方法应用SASV8.0统计分析软件中的二次正交旋转组合设计方案,进行冷冻干燥保护剂组分配比优化的试验设计,并通过响应面法分析各因素对响应值的效应关系。应用优化的冻干保护剂配方进行3次重复冻干试验,验证预测结果的准确性。结果经优化后,保护剂各组分最佳配比为:蔗糖15%,甘油3%,山梨醇15%,脱脂乳15%。应用优化保护剂进行的3次重复冻干试验,菌体冻干存活率的平均值为71.6%,与预测值(73.6%)基本相符。结论应用二次正交旋转组合设计结合响应面法,优化了猪源罗伊乳杆菌的冷冻干燥保护剂组分。     

金黄色葡萄球菌GapC蛋白与鼠伤寒沙门菌鞭毛蛋白的融合表达及其活性

目的在大肠埃希菌中融合表达金黄色葡萄球菌(Staphylococcus.aureus,S.aureus)GapC蛋白与鼠伤寒沙门菌鞭毛蛋白,并检测其甘油醛-3-磷酸脱氢酶(glyceraldehyde-3-phosphate dehydrogenase,GAPDH)活性。方法采用PCR技术分别扩增鼠伤寒沙门菌鞭毛蛋白flic基因和S.Aureus GapC基因,通过overlap PCR将这两段基因拼接并克隆至载体pQE30a,构建重组表达质粒pQE30-flic-GapC,将重组表达质粒转化E.coli XL-blue,IPTG诱导表达,表达产物经镍柱亲和层析试剂盒纯化后,进行SDS-PAGE及Western blot分析,并检测其GAPDH活性。结果重组表达质粒pQE30-flic-GapC经双酶切及测序鉴定证明构建正确;表达产物相对分子质量约95 000,最佳诱导表达时间为5 h,主要以包涵体形式存在,占菌体总蛋白的31.4%;纯化产物可与小鼠抗S.aureus全菌体多抗血清和抗鼠伤寒沙门菌全菌体多抗血清发生特异性反应,GAPDH活性为(0.337±0.019)。结论成功表达并纯化了具有较高生物学活性的flic-GapC融合蛋白,为S.aureus亚单位疫苗的研究奠定了基础。     

不同诱导剂对工程菌发酵及重组蛋白表达的影响

目的观察不同诱导剂对工程菌发酵及HSP-MUC1重组蛋白表达的影响,从而选取最佳诱导表达条件。方法分别用IPTG和乳糖作为诱导剂,发酵表达HSP-MUCI重组蛋白质,并对重组蛋白质表达量和性状进行分析。结果用IPTG诱导发酵的菌体经普通匀浆法即可将细菌破碎;而用乳糖发酵的菌体经普通匀浆法不能破菌,通过延长发酵时间也能达到与IPTG诱导相同的表达量。结论乳糖可以作为基因工程重组蛋白的理想诱导剂。     

手性衍生-高效液相色谱法拆分菌体细胞壁中α,ε-二氨基庚二酸非对映异构体

建立了一种手性衍生.高效液相色谱荧光检测法拆分菌体细胞壁中α,ε-二氨基庚二酸(DAP)3种非对映异构体(LL、DD和rneao)的方法.100 mg干细胞样品经2 mL 6 mol/L HCI于110℃下水解8 h,水解液用Na2CO<,3>调pH至中性.水解后的样品经邻苯二甲醛(OPA)和N-乙酰基-L-半胱氨酸手性衍生后,使用乙腈与0.05 mol/L的磷酸盐缓冲液(10:90,V:V)混合溶剂洗脱,反相C18柱(250 mm×4.6 mm,5 μm)分离,荧光检测器检测(ex=350 nm,em=455 nm).α,ε-二氨基庚二酸(DAP)3种非对映异构体(LL、DD和meso)的手性衍生物得到良好分离.对7个样品分析结果表明,适用于菌体细胞壁中DAP的3种非对映异构体的分离.     

密螺旋体Reiter株纯化轴丝在梅毒血清学诊断中的应用

本试验以纯化的 Reiter 株轴丝为抗原,建立了 AF-ELISA 试验方法。用该方法检测了35份自家免疫病人血清、285份非梅毒病人血清及78份各期梅毒病人血清,并同时与 FTA-ABS 进行比较,结果 AF-ELISA 特异性为99.3%,FTA-ABS 为99.7%,两者敏感性为100%。     

Morphology development from rod-like to nanofibrillar structures of dispersed poly (lactic acid) phase in a binary blend with poly (vinyl alcohol) matrix along the spinline

The morphological evolution of thermoplastic poly (vinyl alcohol) (PVA) and poly (lactic acid) (PLA) blend filaments along the spinline is investigated for the first time. Emphasis of the study is given on considering the axial velocity gradient and tensile stress that influence the final state of deformation of the dispersed PLA phase. In this study, pieces of the PVA/PLA blend filaments at different locations along the spinline are collected by using a special self-constructed fiber-capturing device. This fiber-capturing device allows closer off-line study of the morphological properties of PVA/PLA blend filaments. The axial velocity gradient at different zones along the spinline is calculated from velocity data using Laser Doppler Velocimetry (LDV) technique. The tensile stress is determined from the momentum balance equation. It is observed that the fibrillation process takes place up to a certain distance from the die exit, where the polymeric PVA/PLA blend filament reaches its glass transition temperature. In this region, the axial velocity and tensile stress undergoes major changes. A phase inversion of dispersed PLA phase from rod-like structures to continuous long thin fibrils has been found at the point in which the axial velocity gradient reaches a maximum value.     

热拉伸过程中PE–UHMW/PE–HD共混纤维的晶体结构演变

将超高分子量聚乙烯(PE–UHMW)与高密度聚乙烯(PE–HD)按照质量比为6︰4进行共混熔融纺丝,并对初生丝进行高倍热拉伸制得PE–UHMW/PE–HD共混纤维。利用广角X射线衍射、差示扫描量热、声速取向试验等方法研究了PE–UHMW/PE–HD共混纤维在热拉伸过程中的晶体结构演变过程。研究显示,随着热拉伸过程的进行,纤维的分子链沿纤维的轴向取向度逐渐增加,熔融峰温度逐渐升高,结晶度逐渐增加;沿径向的晶粒尺寸逐渐减小,而沿轴向的晶粒尺寸逐渐增加,即形成了更细长的晶粒;晶体的取向度逐渐增加。当拉伸倍数由1增大至6时,上述现象变化显著,当拉伸倍数由9增至15时,上述现象变化缓慢。与PE–HD共混后的纤维结晶度、晶体取向度和分子链取向度更高,晶粒更加细长。     

Geometrical conditions indispensable for muscle contraction

Computer simulation has uncovered the geometrical conditions under which the vertebrate striated muscle sarcomere can contract. First, all thick filaments should have identical structure, namely: three myosin cross-bridges, building a crown, should be aligned at angles of 0°, 120°, 180°, and the successive crowns and the two filament halves should be turned around 120°. Second, all thick filaments should act simultaneously. Third, coordination in action of the myosin cross-bridges should exist, namely: the three cross-bridges of a crown should act simultaneously and the cross-bridge crowns axially 43 and 14.333 nm apart should act, respectively, simultaneously and with a phase shift. Fifth, six thin filaments surrounding the thick filament should be turned around 180° to each other in each sarcomere half. Sixth, thin filaments should be oppositely oriented in relation to the sarcomere middle. Finally, the structure of each of the thin filaments should change in consequence of strong interaction with myosin heads, namely: the axial distance and the angular alignment between neighboring actin monomers should be, respectively, 2.867 nm and 168° instead of 2.75 nm and 166.15°. These conditions ensure the stereo-specific interaction between actin and myosin and good agreement with the data gathered by electron microscopy and X-ray diffraction methods. The results suggest that the force is generated not only by the myosin cross-bridges but also by the thin filaments; the former acts by cyclical unwrapping and wrapping the thick filament backbone, and the latter byelongation.     

Hydrolysis of human horny cells by alkaline protease: Morphological observation of the process

The interaction of highly purified alkaline protease fromBacillus sp. KSM-K16 with the horny cells of human skin contained in skin grime was directly visualized by electron microscopy. It became clear that the protease first penetrates the horny cells and then adsorbs, mainly onto the internal structure of the cells at the initial stage of hydrolysis, and directly hydrolyzes the keratin filaments, though the marginal band surrounding them retains its original shape. Then, hydrolysate produced from the keratin filaments flows out of the cell, and early in the hydrolysis process keratin filaments decrease and then disappear, leaving a marginal band, i.e., the cell turns to a hollow state. As a result, the remaining marginal band loses support from inside the cell, thus promoting cleavage and dispersion. Until this stage in the protease reaction, the remarkable liberation of hydrolysis products as water-soluble protein does not occur.     

Structure–property evolution of poly(ethylene terephthalate)/poly(trimethylene terephthalate) side-by-side self-crimp filament

To investigate the microstructure and mechanical properties of self-crimping two-component side-by-side bicomponent filament, this paper focuses on systematically investigating the structure–property evolution of poly(ethylene terephthalate) (PET)/poly(trimethylene terephthalate) (PTT) side-by-side bicomponent filament prepared via melt spinning with various component ratios, drawing and heating treatment. The investigation was operated upon the combination of morphology analysis, thermal analysis, crystallization, and orientation analysis. The variation of cross section and curl-morphology, crystallization, and microstructures mainly containing lamellar and microfibrillar crystals as well as their effects on the mechanical and self-crimping properties were discussed. As the draft ratio (DR) increases, the crystallinity, sonic orientation factor, tensile strength, and crimp-recovery rate of the filaments were increased. The sonic orientation factor in the crystalline region decreases from 0.923 to 0.777 but increases from 0.677 to 0.903 in the amorphous region. In contrast to the variation of the DR, heating temperature has a limited effect on the tensile strength of the PET/PTT hybrid filaments. Crimp-recovery rate, however, first increases to 11.8 and then decreases to 9.8 with an increasing heating temperature from 144 to 168°C. Most of these behaviors have been attributed to changes in the ratio of contractile stress for both PTT and PET components, originating from microstructural evolution in hybrid filaments, including crystal growth, breakage, deflection, and deformation of chains along the axial direction. As a summary, an interpretive diagrammatic sketch has been proposed to clarify the structure–property relationships of the commercial PET/PTT filaments.     

Attenuating PP/PET bicomponent melt blown microfibers

This research investigated the attenuation of polypropylene (PP)/poly(ethylene terephthalate) (PET) bicomponent (bico) filaments during the melt blowing (MB) process. It was found that both mono‐ and bi‐component filaments attenuated from several hundred micrometers to a few micrometers in the first 5 centimeters from the die. However, fiber diameter distributions were found to be broad in these regions. The filaments were attenuated much slower but exhibited narrower diameter distributions as they moved further from the die. The diameters of bico MB filaments were between those of 100% PP and 100% PET filaments. The PET component in a bico filament controls the final fiber diameter. During melt blowing, filaments were aligned orderly with the airflow direction in a short distance near the die. Filament entanglements started at about 2.5 cm from the die and became more and more randomly oriented as the distance‐from‐the‐die (DFD) increased. The fiber diameter distribution of bico filaments was broader than that of 100% PP filaments. A higher airflow rate led to a narrower fiber size distribution for bico filaments.     

The microindentation hardness behaviour of carbon filaments,glassy carbons,and pyrolytic graphites

The microindentation hardness behaviour of carbon filaments has been studied by indenting a Vickers diamond into the sides and end-sections of a range of large, pitch-based, filaments. Identical impressions were obtained on filament sides regardless of prior coating with Au/Pd alloy because of the existence of ordered outer regions on all filaments. Because of this fact and the necessary limiting of loads to <100 g, “unrecovered” hardnesses only were obtained. Similar ordered layers and anomalous indentation behaviour were found on glassy carbons and the general microindentation characteristics of carbon filaments are much closer to those of glassy carbons than pyrolytic graphites. Both the side-measured and the somewhat higher end-section-measured hardnesses of filaments heat-treated to ~2700°C decrease considerably with increasing filament anisotropy. It is suggested that this diminishing resistance to indenter penetration results from a decreasing lateral coupling between microfibrils as the filaments become more structurally ordered. Calculations of yield strengths from the measured hardnesses indicate that while the Marsh microplastic concept of fracture may have some validity for carbon filament compression failures it may not be relevant to tensile fracture behaviour of oriented filaments.     

Formation Mechanism Analysis of Shear-Induced Microgel Filaments during Microfluidic Gelation

Dynamic microfluidic gelation enables the fabrication of bundle-structured multiple parallel microgel filaments from an aqueous two-phase system. The formation mechanism of shear-induced filaments from an alginate (Alg)/polyvinyl alcohol (PVA) blend is studied using red-colored PVA and a titanium alkoxide PVA crosslinker. Bundle-structured Alg microgel filaments are formed through contact with a Ca²⁺ crosslinker. In this process, the PVA acts as a sacrificial polymer to maintain the Alg gel filaments because approximately 90% of the red-colored PVA is released from the Ca²⁺-crosslinked Alg gel filaments into the wash water. In addition, the fabrication of PVA gel filaments shows that the sacrificial PVA is also transformed into fibrillar domains under shear. However, the filament structure cannot be formed from a single-phase PVA/Alg solution. These results clearly show that the bundle-structured gel filaments are maintained by preventing the fusion of filaments during gelation based on the tendency of the non-crosslinked filaments to cause splitting of the gelled filaments.     

Physical characteristics and morphologies of PTT/m-iPP bi-component filaments of the island-in-sea type

The work discusses preparation, structure and selected properties of two special filaments based on poly(trimethylene terephthalate) (PTT) and metallocene isotactic polypropylene (m-iPP) bi-component filaments of the island-in-sea type. PTT microfilaments are formed by removing m-iPP from PTT (island)/m-iPP (sea) conjugated filaments. m-iPP exhaust dyeable filaments are produced from m-iPP (island)/PTT (sea) conjugated filaments. This study thoroughly investigates the physical characteristics and morphologies of PTT/m-iPP bi-component filaments of the island-in-sea type. The dye exhaustions of the fabrics made of PTT series filaments are compared. Experimental DSC results indicated that PTT and m-iPP crystallites formed an immiscible system. The tenacity of the PTT/m-iPP (and m-iPP/PTT) conjugated filaments initially declined and then increased as the proportion of m-iPP (and PTT) increased. Clearly, the 50/50 weight ratio PTT/m-iPP had the lowest tenacity. The experimental crystallinities revealed that PTT and m-iPP crystallites easily formed individual domains, indicating that PTT and m-iPP together constituted an immiscible system. On the morphology, the blends were had a dispersed phase structure. PTT and m-iPP polymers were immiscible. In this investigation, PTT microfilaments were produced and a large size from 2.3 to 2.6 μm in diameter was clearly observed. m-iPP exhaust dyeable filaments were also prepared. The dye exhaustions of various fabrics followed the order, m-iPP exhaust dyeable filaments, conventional PTT filaments, PTT microfilaments respectively.