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101.
以谷氨酸棒杆菌YILM 1504为出发菌,研究了生物素对L-异亮氨酸产量的影响。基于多梯度生物素对比实验及中后期生物素外源添加实验,确定了发酵液中最佳生物素浓度及补料工艺。结果显示:在低浓度生物素发酵液中,最适生物素浓度为45μg/L,此时产酸达到42.5g/L,糖酸转化率达到最高,为13.4%;在大于60μg/L高浓度生物素发酵液中,产酸最高为22g/L,表明高浓度生物素不利于产酸发酵。在5L发酵罐中,初始生物素浓度为30μg/L,18,32,42h分别添加10g/L玉米浆(15μg/L生物素),54h产酸量达到了44.5g/L,比初始生物素浓度为30μg/L,后期不补料产酸量提高了49.8%。 相似文献
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103.
Curcumin, one of the major constituents of Curcuma longa, has been shown to inhibit depolarization-evoked glutamate release from rat prefrontocortical nerve terminals by reducing voltage-dependent Ca(2+) entry. This study showed that curcumin inhibited ionomycin-induced glutamate release and KCl-evoked FM1-43 release, suggesting that some steps after Ca(2+) entry are regulated by curcumin. Furthermore, disrupting the cytoskeleton organization using cytochalasin D abolished the inhibitory action of curcumin on ionomycin-induced glutamate release. Mitogen-activated protein kinase kinase (MEK) inhibition also prevented the inhibitory effect of curcumin on ionomycin-induced glutamate release. Western blot analyses showed that curcumin decreased the ionomycin-induced phosphorylation of extracellular signal-regulated kinase 1 and 2 (ERK1/2) and synaptic vesicle-associated protein synapsin I, the main presynaptic target of ERK. These results show that curcumin-mediated inhibition of glutamate release involves modulating downstream events by controlling synaptic vesicle recruitment and exocytosis, possibly through a decrease of MAPK/ERK activation and synapsin I phosphorylation, thereby decreasing synaptic vesicle availability for exocytosis. 相似文献
104.
通过对732阳离子交换树脂对屎肠球菌谷氨酸脱羧酶(glutamate decarboxylase,GAD,EC4.1.1.15)活性的影响进行探讨,构建了732阳离子交换树脂-细胞GAD复合转化体系。结果表明:经含0.2?mol/L?L-谷氨酸(L-glutamic acid,L-Glu)的0.2?mol/L乙酸-乙酸钠缓冲液(pH?4.2)平衡的732阳离子交换树脂可显著提高屎肠球菌细胞GAD的转化活性,γ-氨基丁酸(γ-aminobutyric acid,GABA)产量较对照组增加了32.30%;L-Glu/谷氨酸一钠(monosodium glutamate,MSG)(2∶1)固体混合物能有效调节反应体系的pH值和维持反应液的底物浓度,显著增加GABA产量,当添加量为30?g/L时,GABA产量较不添加L-Glu/MSG(2∶1)固体混合物的对照组提高了52.40%;732阳离子交换树脂与L-Glu/MSG(2∶1)固体混合物对细胞GAD的转化活性具有协同促进作用,适宜的732阳离子交换树脂-细胞GAD复合转化体系组成为732阳离子交换树脂10?g、0.3?mol/L?MSG溶液(溶于0.2?mol/L乙酸-乙酸钠缓冲液,pH?4.2)10?mL、100?mg/mL屎肠球菌细胞悬液10?mL和L-Glu/MSG(2∶1)混合物30?g/L。在该反应体系下,80?r/min、40?℃水浴振荡器反应24?h,GABA产量为(4.57±0.11)mmol,较对照组GABA产量((2.29±0.08)mmol)提高了99.56%。 相似文献
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107.
Sheng‐Yuan Yang Bo Yu Zhao‐Xin Lu Xiao‐Mei Bie Qian Lin Li‐Jun Sun 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(3):389-392
The culture conditions for glutamate decarboxylase (GAD) production under submerged fermentation by Streptococcus salivarius ssp. thermophilus were investigated. The results indicated the optimum culture medium was composed as follows: 15.0 g L?1 of peptone, 12.5 g L?1 of beef extract, 12.5 g L?1 of sucrose, 1.03 g L?1 of dipotassium hydrogen phosphate, 5 g L?1 of sodium acetate, 2 g L?1 of ammonium dibasic citrate, 2.12 g L?1 of calcium chloride, 1 g L?1 of Tween 80, and initial pH 6.79. The optimum culture temperature and time were 37 °C and 12 h, respectively. Under these conditions, GAD production was 257.46 ± 5.12 U, which was about 1.45‐fold that of Man–Rogosa–Sharpe broth. Copyright © 2008 Society of Chemical Industry 相似文献
108.
脉冲—旋风组合气流干燥系统研究 总被引:1,自引:0,他引:1
通过对脉冲气流干燥器与旋风气流干燥器特点的分析,结合工厂工艺要求,研制了脉冲-旋风组合气流干燥装置。实践表明,这种组合干燥系统可充分利用两种干燥器的特点,具有传热,传质效果好,热效率高,适应能力强的特点。适用于初始物料水分较高(>10%w),潮湿状态有一定粘结性的松散粉粒的干燥。该组合干燥装置已经用于粉状谷氨酸钠不同品种物料的干燥。 相似文献
109.
Dominguez Juan M.; Balfour Margaret E.; Lee Han S.; Brown Jennifer L.; Davis Brooke A.; Coolen Lique M. 《Canadian Metallurgical Quarterly》2007,121(5):1023
Studies have emphasized the role of the medial preoptic area (MPOA) as an important site for the regulation of male sexual behavior. Indeed, ablations of the MPOA impair sexual behavior, whereas stimulation of the MPOA enhances behavior. Furthermore, neural activity in the MPOA increases with mating. The current study tested the hypothesis that activation of N-methyl-D-aspartate (NMDA) receptors occurs in MPOA neurons and is essential for the expression of male sexual behavior in rats. Results indicate that nearly all MPOA neurons that expressed Fos following mating also contained the NR1 subunit of NMDA receptors. Furthermore, mating increased phosphorylation, thus activation, of NR1 in the MPOA. Additionally, blocking NMDA receptors significantly decreased mating-induced Fos expression and mating-induced phosphorylation of NMDA receptors and impaired male sexual behavior. These results provide evidence that mating activates NMDA receptors in the MPOA and that this activation is important for the expression of male sexual behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
110.
Glutamatergic innervation in bone 总被引:3,自引:0,他引:3
Chenu C 《Microscopy research and technique》2002,58(2):70-76
Bone is highly innervated, and evidence for a regulation of bone metabolism by nerve fibers has been suggested by many clinical and experimental studies. However, the nature of the neuromediators involved in these processes has not been well documented. Glutamate (Glu), a major neuromediator of the central nervous system (CNS), was recently identified in nerve fibers running in bone marrow in close contact with bone cells, suggesting that Glu may also act as a neuromediator in this tissue. During the last few years, all the machinery required for glutamate signalling in the CNS was demonstrated in bone. Osteoblasts and osteoclasts express ionotropic Glu receptors (iGluR) (NMDA, AMPA, and Kainate) and metabotropic Glu receptors (mGluR) as well as Glu transporters. Electrophysiological studies have demonstrated that NMDA receptors (NMDAR) and mGluR are functional on bone cells. NMDAR are involved in osteoclast formation and bone resorption and preliminary studies suggest that they may also participate in mechanisms underlying osteoblast proliferation or differentiation, providing evidence for a direct action of Glu on bone cells. The bone loss induced in a model of sciatic neurectomy in growing rats is associated with a decrease of glutamatergic innervation, suggesting that Glu released by nerve fibers may contribute to the regulation of bone remodeling. The manipulation of Glu action in bone may, therefore, represent a new therapeutic target for pathologies associated with modifications of bone remodeling. 相似文献