谷氨酸菌体破碎条件的优化研究

以释放胞内物质为主要目的的细胞破碎条件,采用均质破碎法、超声波法、加酶法和碱性自溶法等对谷氨酸菌作进行破碎试验,并对其相应的工艺参数进行了优化研究。结果表明,使用碱性自溶法在pH10.0,温度70℃,干菌浓度为10％时,自溶40min后蛋白质的释放率接近80％,表明该法对释放胞内物质的作用效果较理想。     

肾综合征出血热病毒LR1株在Vero细胞上适应的特性研究

选取不同代次的ＬＲ１毒株在Ｖｅｒｏ细胞上传代适应,不同天数连续动态观察细胞病变情况,同时用免疫荧光法和ＥＬＩＳＡ进行抗原检测,收毒前细胞反复冻融及超声波破碎,细胞破碎前后用ＥＬＩＳＡ检测抗原含量,半微量空斑法检测病毒滴度。结果证明：ＬＲ１株病毒能在Ｖｅｒｏ细胞上产生细胞病变,病变程度与其毒力明显相关;ＬＲ１株病毒在Ｖｅｒｏ细胞上繁殖的最佳收毒时间为１１天左右;病毒释放性较差,冻融和超声波破碎细胞能明显提高其抗原含量和病毒滴度     

高质量毕赤酵母基因组DNA提取方法比较

旨在比较5种毕赤酵母基因组DNA的提取法,以便获得简便高效的提取高质量酵母基因组DNA的优化方法。分别使用蜗牛酶破壁法,超声波破碎法,液氮研磨法,Lyticase破壁法,试剂盒法提取毕赤酵母基因组DNA,然后进行DNA电泳检测以及紫外分光光度计测定DNA浓度和纯度。结果显示,5种方法均能提取出酵母基因组DNA,而酶法所提取的酵母基因组DNA质量最好。由此证实,蜗牛酶法成本低、效果好,是理想的提取高质量酵母基因组DNA的方法,完全满足后续试验要求。     

颠茄胚囊细胞原生质体的酶法分离和观察

分离被子植物雌配子原生质体对发展植物受精工程有着重要意义。最近几年,虽然用酶法分离生活的胚囊已有一些成功的报道。但对分离组成胚囊细胞的原生质体前人还没有进行过尝试。1984年我们首次从烟草生活胚珠中分离出卵细胞、中央细胞、助细胞和反足细胞的原生质体。最近我们又用颠茄胚珠为材料,采用酶解压片技术进行分离胚囊细胞的原生质体,也取得预期的结果。获得了有活性的卵细胞、中央细胞和助细胞的原生质体。从而证明这项技术是有推广应用价值的。在观察中发现用酶法分离生活胚囊细胞的原生质体,能     

不同细胞破碎方法对无细胞蛋白表达系统细胞抽提物活性的影响

无细胞蛋白表达系统由于能够有效表达膜蛋白等有毒性蛋白,因此近二十年受到了关注,其蛋白表达产率有了显著的提高。细胞抽提物活性的高低是无细胞蛋白表达系统高效运行的关键,若找到简单易行的活性评估方法,将大大降低成本及时间。葡萄糖-6-磷酸脱氢酶 (glucose-6-phosphate dehydrogenase, G-6-PDH)是糖代谢的戊糖磷酸途径中的关键调控酶,该酶可以被用来评估细胞抽提物的活性。以G-6-PDH的活性为指标对无细胞蛋白表达系统中的抽提物活性进行评价,并利用G-6-PDH活性评价体系对机械破碎、高压破碎以及超声破碎三种破碎方法进行了比较,得出了三种破碎方法的最佳破碎条件。机械破碎最佳破碎条件是5 000r/min, 用直径0.1 mm玻璃珠,破碎6次;高压破碎的最佳破碎压力为1 300bar;超声破碎最佳破碎条件是功率强度为总功率的60%,破碎30次。酶活性测定结果显示机械破碎和超声破碎得到的抽提物活性比高压破碎得到的抽提物活性略高。     

创新型设计细胞破碎自控与检测装置及其应用

针对传统的细胞破碎工艺存在的操作复杂,缺乏连续性,容易出现人为操作误差及无法保证提取物品质等问题,本研究基于自动化与控制、物联网、软件开发与应用等先进的智能化技术,提出了一种细胞破碎自动化控制与检测装置及其实现方法的创新设计理念,保证破碎过程的连续性、操作的规范性、破碎后保持提取物高活性的品质安全性等,使得细胞破碎过程更简单化、自动化、智能化、规范化及精准化。     

细胞焦亡法破碎微生物细胞在合成生物学与代谢工程的应用

【背景】细胞焦亡是一种细胞程序性死亡。在古菌和细菌中,gasdermin同源蛋白（GSDM）能够被特定的活化caspase （protease）酶切,从而激活类似于细胞焦亡的效应,产生细胞破碎效果。【目的】合成生物学、代谢工程和生物制造等应用过程中,细胞破碎是不可或缺的一步。利用细胞焦亡法破碎细胞取代传统的破碎方法,可以简化操作、提高生产效益。【方法】在大肠杆菌（Escherichia coli） BW25113中共表达protease和不同来源的GSDM,选择有明显细胞焦亡效应即来源Runella sp.的GSDM进行蛋白截短改造,使其在诱导表达蛋白截短体GSDMJD后能直接激活细胞焦亡效应。对GSDMJD进行过表达优化,获得可控大肠杆菌细胞焦亡菌株。进一步以重组表达蔗糖磷酸化酶为研究模型,验证本系统应用于细胞破碎释放蛋白的效果。【结果】实现了大肠杆菌中细胞焦亡的人为可控。焦亡菌株在诱导表达焦亡相关蛋白2 h后大肠杆菌细胞破碎死亡,内容物释放。将上述系统和超声法应用于制备蔗糖磷酸化酶粗酶液,细胞焦亡法制备的粗酶液的相对酶活显著高于超声法制备的粗酶液。在制备粗酶液的菌液OD₆₀₀值为2.0时,细胞焦亡法制备的粗酶液相对酶活最高并且相较于超声法制备粗酶液,提高了60%的相对酶活。【结论】细胞焦亡提供了一种更加简单快捷、绿色环保的微生物细胞破碎方式,为合成生物学与代谢工程的发展奠定了基础。     

响应面法优化黑变红枣枣皮类黑精细胞破碎和水浴联动提取工艺

研究表明,黑变红枣枣皮类黑精的最大吸收波长为280nm,本试验以黑变红枣枣皮为原料,在单因素试验的基础上,通过响应面分析法优化水浴与细胞破碎联动对黑变红枣枣皮类黑精提取工艺并建立回归模型。结果表明：最佳提取工艺条件为水浴时间100min、水浴温度78℃、细胞破碎时间为53min、细胞破碎功率66%。在此工艺条件下,测得黑变红枣枣皮吸光度为1.072。与理论值1.031相比,相对误差约3.9%。与常规水浴法和细胞破碎提取黑变红枣枣皮类黑精相比,联动水浴和细胞破碎提取效果更好。最佳提取级数为3级,提取率为91.38%。     

从废弃啤酒酵母细胞提取乙醇脱氢酶的新工艺

用细胞破碎与两水相萃取相结合的新工艺从废弃的啤酒酵母细胞中提取乙醇脱氢酶,探讨了影响破碎萃取效率的因素,确定了破碎萃取的最佳工艺条件     

重组含有Epstein—Barr病毒潜伏膜蛋白1（LMP1）基因的杆状病毒在昆虫？…

用杆状病毒表达系统重组病毒,在昆虫细胞中表达了完整的含有ＥＢＶ－ＬＭＰ１基因３个外显子开放读码框架的长２．３ｋｂ的ｃＤＮＡ片段。用重组病毒感染Ｓｆ９细胞,用免疫荧光染色,结果表明：４８小时表达重组蛋白,７２小时细胞较完整,免疫荧光染色强阳性,９６小时后细胞出现破碎。我们采集７２小时的组织培养上清和细胞破碎裂解液,分别采用ＳＤＳ－ＰＡＧＡＥ、ＨＰＬＣ分子筛法,用免疫蛋白印迹法实验证明,表达的蛋白能被     

Disruption of Saccharomyces cerevisiae using enzymatic lysis combined with high-pressure homogenization

The disruption of commercially-available pressed Bakers' yeast (Saccharomyces cerevisiae) was studied using a relatively new high-pressure homogenizer (the Microfluidizer). Initial experiments using only mechanical disruption generally gave low disruption yields (i.e., less than 40% disruption in 5 passes). Consequently combinations of two disruption methods, namely enzymatic lysis and subsequent homogenization, were tested to identify achievable levels of disruption. The enzyme preparation employed was Zymolyase, which has been shown to effectively lyse the walls of viable yeast. Yeast cell suspensions ranging in concentration from 0.6 to 15 gDW/L were disrupted with and without enzymatic pre-treatment. Final total disruption obtained using the combined protocol approached 100% with 4 passes at a pressure of 95 MPa, as compared to only 32% disruption with 4 passes at 95 MPa using only homogenization. A model is presented to predict the fraction disrupted while employing this novel enzymatic pretreatment.Nomenclature a exponent of pressure (-) - b exponent of number of passes (-) - K disruption constant (MPa^-a) - N number of passes (-) - P pressure (MPa) - R total fraction of cells disrupted (-) - Ro fraction of cells disrupted after enzymatic pre-treatment (-) - X cell concentration (dry weight) (gDW/L) abbreviation DW dry weight     

Quantification of Endospore Concentrations of Pasteuria penetrans in Tomato Root Material

Six methods for quantification of the endospore concentrations of Pasteuria penetrans from tomato roots are described. Mortar disruption and machine disruption methods gave the highest estimations (endospores per gram of root material) of 83.7 and 79.0 million, respectively. These methods were significantly superior to incubation bioassay (47.7 million), enzymatic disruption (32.1 million), and enzymatic disruption + flotation (25.8 million) methods. A centrifugation bioassay method gave the lowest estimation of 12.7 million.     

A microscale bacterial cell disruption technique as first step for automated and miniaturized process development

Cell disruption is crucial during recovery of biopharmaceuticals overexpressed in E. coli, which tend to be produced intracellularly as insoluble inclusion bodies. Miniaturized high-throughput systems can accelerate the laborious downstream protocol for such biopharmaceuticals and enable integrated process-development. A fast and robust cell disruption method reflecting the protein and impurity profile of homogenates obtained by large-scale methods is required for such an approach. We established a miniaturized bead mill for parallel mechanical cell disruption at the microscale. Its total protein and impurity release, protein pattern, and particle size distribution were compared to results from microscale enzymatic digestion and referred to laboratory-scale high-pressure homogenization. Bead mill disruption led to equivalent protein and impurity release as well as to the same particle size profile as the large-scale reference. In contrast, lysates obtained by enzymatic digestion contained only 30–47% of overall protein, 17% of dsDNA, and 7–10% of endotoxin compared to those obtained by high-pressure homogenization; also larger debris was present in lysates after enzymatic digestion. The established method is fast, efficient, robust and comparable to current large-scale standards, allowing for parallelization of experiments. Thus, it is the method of choice for rapid integrated process development at the microscale.     

Enhanced disruption of Candida utilis using enzymatic pretreatment and high-pressure homogenization

The enhancement of the overall disruption of a native strain of Candida utilis (ATCC 9226) was studied using a combination of two methods, namely, pretreatment in the form of partial enzymatic lysis by Zymolyase followed by mechanical disruption in a Microfluidizer high-pressure homogenizer. The cells were grown in both batch and continuous cultures to examine the effect of specific growth rate on disruption. Cell suspensions ranging in concentration from 7 to 120 g DW/L were disrupted with and without enzymatic pretreatment. For yeast grown in batch culture, final total disruption obtained using the combined protocol approached 95% with four passes at a pressure of 95 MPa, as compared with only 65% disruption using only mechanical homogenization. A modified model was developed to predict the fraction disrupted by the enzymatic pretreatment-mechanical homogenization two-stage process. Predicted disruptions agreed favorably with experimental observations (maximum deviation of 20%) over a wide range of operating conditions. (c) 1994 John Wiley & Sons, Inc.     

Inactivation of MXR1 Abolishes Formation of Dimethyl Sulfide from Dimethyl Sulfoxide in Saccharomyces cerevisiae

Dimethyl sulfide (DMS) is a sulfur compound of importance for the organoleptic properties of beer, especially some lager beers. Synthesis of DMS during beer production occurs partly during wort production and partly during fermentation. Methionine sulfoxide reductases are the enzymes responsible for reduction of oxidized cellular methionines. These enzymes have been suggested to be able to reduce dimethyl sulfoxide (DMSO) as well, with DMS as the product. A gene for an enzymatic activity leading to methionine sulfoxide reduction in Saccharomyces yeast was recently identified. We confirmed that the Saccharomyces cerevisiae open reading frame YER042w appears to encode a methionine sulfoxide reductase, and propose the name MXR1 for the gene. We found that Mxr1p catalyzes reduction of DMSO to DMS and that an mxr1 disruption mutant cannot reduce DMSO to DMS. Mutant strains appear to have unchanged fitness under several laboratory conditions, and in this paper I hypothesize that disruption of MXR1 in brewing yeasts would neutralize the contribution of the yeast to the DMS content in beer.     

Increased disruption resistance of Candida utilis grown from survivors of enzymatic lysis combined with high-pressure homogenization

The resistance of Candida utilis (ATCC 9226) to disruption as a result of enzymatic pretreatment combined with high-pressure homogenization was found to increase when the yeast was grown from an inoculum which had previously been subjected to enzymatic pretreatment combined with high-pressure homogenization. The inoculum thus consisted of a mixture of undisrupted, viable cells and non-viable cells. The enzyme preparation employed was Zymolyase, which depolymerizes various components of the cell walls of viable yeast. A Microfluidizer was used for the high-pressure homogenization step. In order to obtain the 'disruption-resistant' cell fraction for use as an inoculum, 'normal' C. utilis was enzymatically pretreated, and subsequently homogenized (herein referred to as Microfluidization) using either three or 10 passes through the Microfluidizer at an operating pressure of 95 MPa. Yeast grown from the survivors of the enzyme/3-pass treatment were found to be somewhat more resistant to disruption by either enzymatic pretreatment alone or to enzymatic pretreatment followed by Microfluidization. Cells grown from enzyme/ 10-pass treated inocula exhibited the highest resistance to disruption. The 'disruption-resistant' fraction exhibited this characteristic through three serial re-cultivations. Possible mechanisms for the increased 'disruption-resistance' of this isolated population of C. utilis are presented.     

Relation between cell disruption conditions, cell debris particle size, and inclusion body release

The efficiency of physical separation of inclusion bodies from cell debris is related to cell debris size and inclusion body release and both factors should be taken into account when designing a process. In this work, cell disruption by enzymatic treatment with lysozyme and cellulase, by homogenization, and by homogenization with ammonia pretreatment is discussed. These disruption methods are compared on the basis of inclusion body release, operating costs, and cell debris particle size. The latter was measured with cumulative sedimentation analysis in combination with membrane-associated protein quantification by SDS-PAGE and a spectrophotometric peptidoglycan quantification method. Comparison of the results obtained with these two cell debris quantification methods shows that enzymatic treatment yields cell debris particles with varying chemical composition, while this is not the case with the other disruption methods that were investigated. Furthermore, the experiments show that ammonia pretreatment with homogenization increases inclusion body release compared to homogenization without pretreatment and that this pretreatment may be used to control the cell debris size to some extent. The enzymatic disruption process gives a higher product release than homogenization with or without ammonia pretreatment at lower operating costs, but it also yields a much smaller cell debris size than the other disruption process. This is unfavorable for centrifugal inclusion body purification in this case, where cell debris is the component going to the sediment and the inclusion body is the floating component. Nevertheless, calculations show that centrifugal separation of inclusion bodies from the enzymatically treated cells gives a high inclusion body yield and purity.     

N-酰基高丝氨酸内酯酶的分子改造及酶学特性

革兰氏阴性细菌的群体感应系统利用N-酰基高丝氨酸内酯（N-acyl-homoserine lactone, AHL）作为主要信号分子诱导致病因子表达,造成细菌性病害. N-酰基高丝氨酸内酯酶（N-acyl-homoserine lactonase, AHLase）能水解AHL分子的内酯键,减弱致病菌的危害.本研究利用从苏云金芽孢杆菌克隆的N-酰基高丝氨酸内酯酶基因（auto inducer inactivation A, aiiA）,根据Swiss-model模拟aiiA所编码的AiiA蛋白三维结构,预测可能形成的分子内盐桥、活性中心位点等,利用环状诱变方法对AiiA进行定点突变,以期提高其酶活力和热稳定性等酶学性能.对AiiA及其突变蛋白酶学特性分析结果发现,突变体AiiA-N65K-A206E酶活力要比野生型AiiA-wild提高87.4%,并表现出良好的热稳定性和储存稳定性;37 ℃温浴30 min后酶活力剩余73;9%,比AiiA-wild有了大幅提高;4 ℃储存120 h后酶活力剩余12.9%,而AiiA-wild丧失酶活力.酶动力学分析表明,AiiA-N65K-A206E酶促反应的米氏常数Km为1.23 mmol/L,与野生型相当;最大反应速率Vmax为32.36 μmol/L/min,比野生型有较大提高.本研究表明,利用定点突变技术改造AiiA的分子结构,可有效提升AiiA酶活力、热稳定性和储存稳定性.本研究结果为进一步阐明AiiA结构与功能的关系,促进AiiA在植物病害生物防治上的应用,提供了有益的参考和新的思路.     

Disruption of a filamentous fungal organism (N. sitophila) using a bead mill of novel design II. Increased recovery of cellulases

A native strain of Neurospora sitophila was disrupted using enzymatic pretreatment combined with mechanical disruption in order to facilitate recovery of constitutive cellulases. Exceptional disruption (approaching 100%) was achieved when the enzymatic pretreatment protocol was used prior to mechanical disruption at a low rotor speed via a new bead mill (the Annu Mill). Further, increased recovery of cellulases (ca. two-fold increases in cellulase activity per unit biomass) appears attainable when this disruption protocol is employed. The enzyme preparation employed was Zymolyase, which lyses the walls of viable fungi. Combined disruption of the mycelial biomass appears to provide a secondary source of cellulases from Neurospora sitophila in addition to the extracellular primary source derived from the filtered (unprocessed) fermentation broth.Nomenclature CMCase carboxymethyl cellulase - FPase filter paper'ase - IU international unit (mol liberated hydrolysis product/min.) - N number of passes through the bead mill (–) - R total fraction of cells disrupted (–) - Ro fraction of cells disrupted after enzymatic pretreatment alone (–) - X cell concentration (dry weight) (gDW/L) Abbreviations DW dry weight     

腺苷甲硫氨酸合成酶的提取纯化研究

腺苷蛋氨酸具有转甲基、转硫和转氨丙基等重要生理作用,已成为治疗疾病的重要药物。目的：为腺苷蛋氨酸合酶的基因克隆做准备。方法：研究了腺苷甲硫氨酸合成酶的提取和纯化。腺苷蛋氨酸合酶为胞内酶,其提取需先进行细胞破碎,然后进行盐析和离子交换层析等方法来纯化。酵母的破壁试验考察了研磨、加入有机溶剂和超声波等不同的破碎方法。结果：超声波破碎法最好,得到粗酶液的酶活力为0．934U／ml;经过硫酸铵盐析后,利用离子交换层析法纯化腺苷甲硫氨酸合成酶,作出了腺苷甲硫氨酸合成酶的穿透曲线和洗脱曲线。