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141.
【目的】考察不同补料工艺对法夫酵母菌株生长和虾青素合成的影响。【方法】对法夫酵母JMU-VDL668和JMU-MVP14菌株在7 L罐中进行分批及分批补料培养; 同时, 测定发酵过程中生物量、虾青素和葡萄糖含量的变化。【结果】采用恒DO补料, 法夫酵母JMU-VDL668菌株获得的生物量最大(64.6 g/L), 是分批培养的2.2倍; 采用恒pH补料发酵, 虾青素的产量最高(20.6 mg/L), 是分批培养的1.5倍。与JMU-VDL668菌株不同, 虾青素高产菌株JMU-MVP14菌株采用恒pH补料, 获得生物量最大(48.5 g/L), 但虾青素产量大大降低(仅17.5 mg/L); 采用脉冲补料, 虾青素产量最高, 达到414.1 mg/L, 与分批发酵相比提高了200.2%; 采用恒DO补料, 生物量(38.5 g/L)和虾青素产量(403.2?mg/L)增加显著, 与分批发酵相比分别提高了133.1%和192.3%。【结论】不同补料工艺对法夫酵母菌株生产虾青素影响很大。其中, 采用恒pH补料工艺, 法夫酵母JMU-VDL668菌株可以获得最高的虾青素产量, 而采用脉冲补料工艺, 最适于法夫酵母JMU-MVP14菌株发酵生产虾青素。 相似文献
142.
Nikki. L. Farnsworth Lorena R. Antunez Stephanie J. Bryant 《Biotechnology and bioengineering》2013,110(7):2046-2057
Dynamic loading has emerged as an important part of cartilage tissue engineering strategies for enhancing tissue production and producing cartilage with functionally competent mechanical properties. As patients in need of cartilage span a range of age groups, questions arise as to the role of age in a cell's ability to respond to dynamic loading. Therefore, this study's goal was to characterize age‐related anabolic and catabolic responses of chondrocytes to dynamic compressive loading. Bovine chondrocytes isolated from juvenile (3‐week‐old) and adult (2‐ to 3‐year‐old) donors were encapsulated in poly(ethylene glycol) hydrogels and subjected to dynamic loading applied intermittently in a sinusoidal waveform at 1 or 0.3 Hz with 5 or 10% amplitude strain up to 2 weeks. Loading significantly enhanced total sulfated glycosaminoglycan (sGAG) production by 220% for juvenile chondrocytes with 0.3 Hz/5% loading and by 88% for adult chondrocytes with 1 Hz/5% loading, while all other loading regimes did not affect or inhibited total sGAG production. Contrarily, deposition of larger matrix molecules of aggrecan and collagen II was either not affected or inhibited by loading. Collagen VI deposition was significantly upregulated by loading but only in adult chondrocytes and under different loading regimes (1 Hz/10% and 0.3 Hz/5%) when compared to total sGAGs. Both cell populations displayed catabolic activity, which appeared to be stimulated by loading. Taken together, findings from this study suggest that loading differentially regulates matrix synthesis and the response is highly dependent on donor age. Biotechnol. Bioeng. 2013; 110: 2046–2057. © 2013 Wiley Periodicals, Inc. 相似文献
143.
Ashley Slocum Mike Burnham Paul Genest Adith Venkiteshwaran Dayue Chen Joseph Hughes 《Biotechnology and bioengineering》2013,110(1):229-239
Virus‐removal filtration technology is commonly used in the manufacturing process for biologics to remove potential viral contaminants. Virus‐removal filters designed for retaining parvovirus, one of the smallest mammalian viruses, are considered an industry standard as they can effectively remove broad ranges of viruses. It has long been observed that the performance of virus filters can be influenced by virus preparations used in the laboratory scale studies (PDA, 2010 ). However, it remains unclear exactly what quality attributes of virus preparations are critical or indicative of virus filter performance as measured by effectiveness of virus removal and filter capacity consistency. In an attempt to better understand the relationship between virus preparation and virus filter performance, we have systematically prepared and analyzed different grades of parvovirus with different purity levels and compared their performance profiles on Viresolve® Pro parvovirus filters using four different molecules. Virus preparations used in the studies were characterized using various methods to measure DNA and protein content as well as the hydrodynamic diameter of virus particles. Our results indicate that the performance of Viresolve® Pro filters can be significantly impacted depending on the purity of the virus preparations used in the spike and recovery studies. More importantly, we have demonstrated that the purity of virus preparations is directly correlated to the measurable biochemical and biophysical properties of the virus preparations such as DNA and protein content and monodispersal status, thus making it possible to significantly improve the consistency and predictability of the virus filter performance during process step validations. Biotechnol. Bioeng. 2013; 110: 229–239. © 2012 Wiley Periodicals, Inc. 相似文献
144.
Clare E.M. Stevenson Richard K. Hughes Michael T. McManus David M. Lawson Stanislav Kopriva 《FEBS letters》2013
Sulfonucleotide reductases catalyse the first reductive step of sulfate assimilation. Their substrate specificities generally correlate with the requirement for a [Fe4S4] cluster, where adenosine 5′-phosphosulfate (APS) reductases possess a cluster and 3′-phosphoadenosine 5′-phosphosulfate reductases do not. The exception is the APR-B isoform of APS reductase from the moss Physcomitrella patens, which lacks a cluster. The crystal structure of APR-B, the first for a plant sulfonucleotide reductase, is consistent with a preference for APS. Structural conservation with bacterial APS reductase rules out a structural role for the cluster, but supports the contention that it enhances the activity of conventional APS reductases. 相似文献
145.
Milagro Mottola Natalia Wilke Luciano Benedini Rafael Gustavo Oliveira Maria Laura Fanani 《生物化学与生物物理学报:生物膜》2013
Ascorbyl palmitate (ASC16) is an anionic amphiphilic molecule of pharmacological interest due to its antioxidant properties. We found that ASC16 strongly interacted with model membranes. ASC16 penetrated phospholipid monolayers, with a cutoff near the theoretical surface pressure limit. The presence of a lipid film at the interface favored ASC16 insertion compared with a bare air/water surface. The adsorption and penetration time curves showed a biphasic behavior: the first rapid peak evidenced a fast adsorption of charged ASC16 molecules to the interface that promoted a lowering of surface pH, thus partially neutralizing and compacting the film. The second rise represented an approach to the equilibrium between the ASC16 molecules in the subphase and the surface monolayer, whose kinetics depended on the ionization state of the film. Based on the Langmuir dimiristoylphosphatidylcholine + ASC16 monolayer data, we estimated an ASC16 partition coefficient to dimiristoylphosphatidylcholine monolayers of 1.5 × 105 and a ΔGp = − 6.7 kcal·mol− 1. The rheological properties of the host membrane were determinant for ASC16 penetration kinetics: a fluid membrane, as provided by cholesterol, disrupted the liquid-condensed ASC16-enriched domains and favored ASC16 penetration. Subphase pH conditions affected ASC16 aggregation in bulk: the smaller structures at acidic pHs showed a faster equilibrium with the surface film than large lamellar ones. Our results revealed that the ASC16 interaction with model membranes has a highly complex regulation. The polymorphism in the ASC16 bulk aggregation added complexity to the equilibrium between the surface and subphase form of ASC16, whose understanding may shed light on the pharmacological function of this drug. 相似文献
146.
Approximately half of the 80 billion tons of crop produced annually around the world remains as residue that could serve as a renewable resource to produce valuable products such as ethanol and butanol. Ethanol produced from lignocellulosic biomass is a promising renewable alternative to diminishing oil and gas liquid fuels. Sugarcane is an important industry in Louisiana. The recently released variety of “energy cane” has great potential to sustain a competitive sugarcane industry. It has been demonstrated that fuel-grade ethanol can be produced from post harvest sugarcane residue in the past, but optimized ethanol production was not achieved. Optimization of the fermentation process requires efficient pretreatment to release cellulose and hemicellulose from lignocellulosic complex of plant fiber. Determining optimal pretreatment techniques for fermentation is essential for the success of lignocellulosic ethanol production process. The purpose of this study was to evaluate three pretreatment methods for the energy cane variety L 79-1002 for maximum lignocellulosic ethanol production. The pretreatments include alkaline pretreatment, dilute acid hydrolysis, and solid-state fungal pretreatment process using brown rot and white rot fungi. Pretreated biomass was enzymatically saccharified and subjected to fermentation using a recombinant Escherichia coli FBR5. The results revealed that all pretreatment processes produced ethanol. However, the best result was observed in dilute acid hydrolysis followed by alkaline pretreatment and solid-state fungal pretreatment. 相似文献
147.
生态植被建设对黄土高原农林复合流域景观格局的影响 总被引:2,自引:0,他引:2
自1999年以来,黄土高原大规模地实施了退耕还林工程,生态环境呈显著恢复态势。采用2002年和2008年两期Spot5遥感影像,评估了退耕还林工程实施前后黄土高原典型农林复合流域土地利用与景观格局的动态变化。结果表明:在退耕还林工程实施的驱动下,流域土地利用变化剧烈,总变化率高达36.77%,主要变化的土地利用类型包括耕地、果园、幼林地、林地等。28.95%的耕地转为其他土地利用类型,其中48.83%转为果园,44.69%转为幼林地。景观格局变化呈明显的空间分布规律,山腰缓坡区以转化为果园为主,中、高海拔多转化为幼林地。退耕后流域生态景观得以优化,呈现良好发展态势。 相似文献
148.
149.
以总生物碱提取率为指标,先用正交试验优化两面针的超声提取工艺,再动态过程精选提取工艺。最佳工艺条件为:复合酶预处理后,以体积分数60%乙醇(盐酸5 g/L)超声(250 W)提取3次,第1次以10倍量溶剂提取15 min,第2次以4倍量溶剂提取12 min,第3次以3倍量溶剂提取9 min,总生物碱提取率87.80%。该工艺高效、节能、省时,为工业生产奠定了实验基础。 相似文献
150.
临海柑橘园橘小实蝇种群数量消长规律 总被引:2,自引:0,他引:2
【背景】近年来,随着种植结构的改变以及南方携虫水果的频繁调运,橘小实蝇逐渐向北扩散危害,对水果生产造成严重威胁。【方法】2008~2010年应用性诱剂的监测方法对柑橘园橘小实蝇种群数量进行了定点、系统的跟踪监测;并结合气象资料和田间调查情况,通过对当旬成虫数量与当旬及其前延逐句气象要素的筛选来建模,进而确定影响橘小实蝇种群数量的主要气象因子。【结果】临海柑橘园橘小实蝇种群数量时序变化呈单峰型曲线,其性诱成虫初见期在6月下旬至8月初,高峰期在9月上旬至11月上旬,11月中旬后成虫数量逐渐下降,到12月下旬未诱集到成虫。气象因子筛选和建模结果表明,柑橘园橘小实蝇成虫种群数量年度变动以旬平均温度为决定要素,季节性变化以旬降雨量为决定要素。【结论与意义】临海柑橘园橘小实蝇种群数量随温度和土壤湿度的增大而增长。本研究对提高橘小实蝇监测预警水平、有效控制橘小实蝇危害具有重要意义。 相似文献