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The increasing demand for propionic acid (PA) production and its wide applications in several industries, especially the food industry (as a preservative and satiety inducer), have led to studies on the low-cost biosynthesis of this acid. This paper gives an overview of the biotechnological aspects of PA production and introduces Propionibacterium as the most popular organism for PA production. Moreover, all process variables influencing the production yield, different simple and complex carbon sources, the metabolic pathway of production, engineered mutants with increased productivity, and modified tolerance against high concentrations of acid have been described. Furthermore, possible methods of extraction and analysis of this organic acid, several applied bioreactors, and different culture systems and substrates are introduced. It can be concluded that maximum biomass and PA production may be achieved using metabolically engineered microorganisms and analyzing the most significant factors influencing yield. To date, the maximum reported yield for PA production is 0.973 g·g-1, obtained from Propionibacterium acidipropionici in a three-electrode amperometric culture system in medium containing 0.4 mM cobalt sepulchrate. In addition, the best promising substrate for PA bioproduction may be achieved using glycerol as a carbon source in an extractive continuous fermentation. Simultaneous production of PA and vitamin B12 is suggested, and finally, the limitations of and strategies for competitive microbial production with respect to chemical process from an economical point of view are proposed and presented. Finally, some future trends for bioproduction of PA are suggested. 相似文献
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BackgroundPyruvic acid (PA), a vital α-oxocarboxylic acid, plays an important role in energy and carbon metabolism. The oleaginous yeast Yarrowia lipolytica (Y. lipolytica) has considerable potential for the production of PA. An increased NaCl concentration reportedly increases the biomass and PA yield of Y. lipolytica.ResultsTo increase the yield of PA, the NaCl-tolerant Y. lipolytica A4 mutant was produced using the atmospheric and room temperature plasma method of mutation. The A4 mutant showed growth on medium containing 160 g/L NaCl. The PA yield of the A4 mutant reached 97.2 g/L at 120 h (0.795 g/g glycerol) in a 20-L fermenter with glycerol as the sole carbon source, which was 28.9% higher than that of the parental strain.ConclusionThe PA yield from Y. lipolytica can be improved by increasing its NaCl tolerance.How to cite: Yuan W, Lin X, Zhong S, et al. Enhanced pyruvic acid yield in an osmotic stress-resistant mutant of Yarrowia lipolytica. Electron J Biotechnol 2020;44. https://doi.org/10.1016/j.ejbt.2020.01.002. 相似文献
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P. Bubber A. Sharma A. Chauhan D. D. Bansal 《Indian journal of clinical biochemistry : IJCB》2013,28(2):193-196
Growth retardation is one of the significant changes in chronic kidney disease (CKD) and is associated with increased morbidity and mortality. Disturbances in growth hormone (GH) are held responsible for several complications in CKD. GH is a protein based peptide hormone which directly or indirectly regulates renal functions to ensure homeostasis. We investigated the effects of growth hormone on plasminogen activators (PA) in rat kidney, PA and plasminogen activator inhibitor (PAI), glucose and fibrinogen in plasma and serum lipid profile. Rats were injected daily with 250 mU GH kg-1 body weight subcutaneously for one week. Growth hormone treatment increased PA activity significantly in rat kidneys as compared to controls. No changes were seen in PA, PAI and fibrinogen levels in the plasma of two groups of rats. There was significant decrease in plasma glucose, total cholesterol and LDL-cholesterol levels in serum of treated group resulting in the decrease of HDL/LDL and total cholesterol/cholesterol ratios. However, triglycerides and VLDL showed significant higher activity in the serum of treated group as compared to controls. Our data suggests that GH administration might improve renal function by increasing PA activity in kidney as well as by reducing the cholesterol content in blood. GH may be effective in improving growth failure as it helps to maintain the normal homeostatic balance. 相似文献
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专利在企业生产经营中的重要性日益显现,其作用已从防御性手段转变成战略性工具。通过对118家高新技术企业363份有效问卷调查数据,从资源观的视角,运用结构方程模型实证研究企业专利获取、专利保护、专利商业化与技术创新绩效的作用机制,并重点探讨专利商业化的中介效应。结果表明:专利获取对专利保护、专利商业化具有显著的正向影响,专利保护对专利商业化具有显著的正向影响;专利获取、专利保护、专利商业化与技术创新绩效均具有显著的正向影响;专利商业化在专利获取与技术创新绩效之间起部分中介作用,而在专利保护与技术创新绩效之间则具有完全中介作用。本研究结论不仅拓展了专利管理与技术创新绩效的理论研究领域,同时为我国高新技术企业在开放式创新环境下通过有效的专利管理提升技术创新绩效提供实践指导。 相似文献
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长江上游降水变化及其对径流的影响 总被引：5，自引：0，他引：5
利用长江上游地区60个国家基本、基准站1960年-2009年的月降水量资料和干流区屏山、寸滩和宜昌3个水文控制站同期径流资料,分区域对长江上游地区的降水量、径流量变化趋势以及降水量和径流量的相关性进行了分析.主要结论如下:①年降水量呈上升和下降趋势的气象站点空间分布相对集中,分别分布在屏山站以上流域和屏山站以下流域;屏山站以下流域和整个长江上游地区年降水量近50年呈现下降趋势,屏山站以下流域秋季降水量的显著减少是长江上游年降水量减少的主要原因;②整个长江上游月降水量趋势从1月-7月以上升趋势为主逐渐转变到8月-12月以下降趋势为主,且月降水量变化趋势空间分布有从3月份至9份月由屏山站以下流域开始逐渐向长江源头过渡的趋势,到9月份整个长江上游基本呈减少趋势;③与降水量变化趋势基本一致,屏山站以下流域寸滩和宜昌站年径流下降趋势显著的主要原因是5月-11月径流的减少,且秋季下降显著,而屏山站春、夏、冬和年径流呈上升趋势,且春季和冬季上升趋势很显著;④整个上游地区面雨量与径流量具有很好的相关性,同期面雨量与径流量在月、季和年尺度上相关性都较显著.屏山以上流域隔月相关比同期相关性强. 相似文献
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[研究目的]美国临时专利申请制度类似于本国优先权制度,已经实施了二十余年,它的存在是否有助于促进发明创造,提高专利质量?若是,则对我国完善知识产权保护,提高专利申请质量,建设知识产权强国具有重要借鉴意义。[研究方法]使用美国USPTO专利数据库,首先考察美国临时专利申请案的特性,然后使用6个与专利质量相关的指标比较了主张临时专利申请案优先权的专利(PA)和未主张临时专利申请案优先权的专利(NPA)的质量差异,并运用Logistics模型分析哪一专利指标与PA的关联性最强。[研究结论]研究表明,2004-2018年间,美国临时专利申请案不但存在国别(地区)差异,而且技术领域也存在显著差异。PA和NPA在平均前引和后引次数、专利权利要求数量、专利家族规模以及审查持续时间方面存在显著差异,主张临时专利申请案优先权的专利确实具有更高的专利质量,且专利请求项数与PA的关联性最强。 相似文献
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Moeness G. Amin 《Journal of The Franklin Institute》2006,343(3):243-256
The Franklin Institute, Philadelphia, PA, awarded the 2005 Benjamin Franklin Medal in Electrical Engineering to Andrew Viterbi for developing an efficient technique that has advanced the design and implementation of modern space and wireless communication systems. He also was a leader in the development of Code Division Multiple Access wireless technologies. 相似文献
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A seven channel polystyrene (PS) microchip has been constructed using a micromilling machine and a high-temperature assembling. Protein A (PA) has been immobilized by a passive sorption on the microchannel walls. Two bioaffinity assays with human immunoglobulin G (hIgG) as a ligand have been carried out. (i) PA as the receptor and fluorescently labeled hIgG (FITC-hIgG) as the ligand, (ii) PA as the receptor with hIgG as the quantified ligand and fluorescently labeled goat anti-human IgG (FITC-gIgG) as the secondary ligand. One incubation step of the assays took only 5 min instead of hours typical for enzyme-linked immunosorbent assay applications. Calibration curves of the dependence of a fluorescence signal on the hIgG concentration in a sample have been obtained in one step due to a parallel arrangement of microchannels. A mathematical model of the PA-FITC-hIgG complex formation in the chip has been developed. The values of the kinetic constant of the PA-FITC-hIgG binding (kon=5.5 m3 mol−1 s−1) and the equilibrium dissociation constant of the formed complex (Kd≤3×10−6 mol m−3) have been obtained by fitting to experimental data. The proposed microchip enables fast evaluation of kinetic and equilibrium constants of ligand-receptor bioaffinity pairs and the ligand quantification. As the use of microfluidic chips for immunoassays is often limited by price, we used procedures and chemicals that allow for an inexpensive construction and operation of the microdevice, e.g., temperature assembling as a fabrication technique, detection via an ordinary digital camera, nonspecific polystyrene as a substrate, passive sorption of biomolecules as an immobilization technique, etc. 相似文献
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积极情感、消极情感和薪酬满意度的关系实证研究 总被引：1，自引：0，他引：1
以3家家电制造企业的145名管理人员为样本，研究了积极情感、消极情感和薪酬满意度的关系。结果表明，消极情感与薪酬满意度不相关，积极情感与薪酬满意度正相关；但当薪酬水平低于一定值时，这种相关关系遭到破坏。因此．把薪酬水平作为奖励信号在解释积极情感与薪酬满意度的关系时要考虑可能存在的边界条件。 相似文献
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由于缺少大功率器件模型,射频功率放大器的设计是工程上的一个难点。本文提出了一种利用功率器件的小信号模型设计功率放大器的方法。 相似文献
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S. K. Mathur Piyush Chandra Sandhya Mishra Peeyush Ajmera Praveen Sharma 《Indian journal of clinical biochemistry : IJCB》2007,22(2):70-73
Asian Indians are known to be at a higher risk of developing T2DM, but the underlying genetic factor in this population is
still not well understood. T2DM is a complex genetic trait and assessment of disease related intermediate phenotypic traits
is an important initial step towards any systematic genomic study. Therefore, in the present study we have assessed diabetes
related intermediate phenotypic traits of insulin secretion and insulin resistance in the patients belonging to this population.
The study included 157 T2DM patients of either sex ranging in age from 45–80 years and 84 non-diabetic subjects with no family
history of diabetes, ranging in age from 45 to 75 years served as controls. Intermediate phenotypic traits studied were BMI,
W: H ratio, fasting free fatty acid level and Insulin resistance and secretion. Diabetics were found to have significantly
higher W: H ratio (p<0.001), FFA (p<0.001) and HOMA-R (p<0.001) as compared to non-diabetics. However, there was no significant
difference in their BMI and HOMA-β. There was a positive correlation between FFA level and HOMA-R among diabetics, but not
among controls. These findings suggest that in abdominal obesity FFA mediated insulin resistance is an important causative
factor underlying T2DM in this population. Moreover, comparable HOMA-β in diabetics reflects compensatory insulin hyper secretion
in these subjects. There is a need to examine relative contribution and precise nature of genetic factor in their tendency
for central obesity, free fatty acidemia and insulin resistance. 相似文献
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Klaus H Theopold 《Journal of The Franklin Institute》2002,339(3):307-314
The Franklin Institute, Philadelphia, PA awarded the 2001 Benjamin Franklin Medal in Chemistry to K. Barry Sharpless for his important innovative scientific contributions to the field of asymmetric catalytic oxidation, which resulted in highly enantioselective processes for the epoxidation, dihydroxylation and aminohydroxylation of olefins. 相似文献
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Brian J. Sullivan 《Journal of The Franklin Institute》2010,347(4):672-680
The Franklin Institute, Philadelphia, PA awarded the 2006 Benjamin Franklin Medal in civil engineering to Ray W. Clough for revolutionizing engineering and scientific computation, and engineering design methods through his formulation and development of the finite element method, and for his innovative leadership in applying the method to the field of earthquake engineering with special emphasis on the seismic performance of dams. 相似文献
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本文以WH153PA热敏微型打印机在医院生化分析仪中的应用为实例,设计了与C8051F120单片机间的硬件接口电路。通过修改C51函数库中的putchar()函数,从而实现打印输出程序设计的简化。对于数据、汉字和曲线的打印输出,分别提出了具体的程序设计方法。对其它型号微型打印机的应用具有参考价值。 相似文献
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Brian J. Sullivan 《Journal of The Franklin Institute》2005,342(6):618-625
The Franklin Institute, Philadelphia, PA, awarded the 2004 Benjamin Franklin Medal in Mechanical Engineering to Roger Bacon for his fundamental research on the production of graphite whiskers and the determination of their microstructure and properties, for his pioneering development efforts in the production of the world's first continuously processed carbon fibers and the world's first high modulus and high-strength carbon fibers, and for his contributions to the development of carbon fibers from alternative starting materials. 相似文献