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探讨从多抗霉素染菌罐批中分离抗杂菌高产菌株的方法。经分离选育出抗杂菌高产株211^#、221^#两株。通过20吨级发酵罐实践表明:211^#、221^#菌株在正常罐批的发酵单位比对照分别提高12%和33%,在染茵罐批的发酵单位比对照分别提高14%和29%。 相似文献
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本实验用相差观祭方法,对照生化分析和有关数据,对卡那霉菌工业发酵过程中,卡那霉菌菌丝细胞在不同发育阶段的结构和功能的变化,进行了研究。提出卡那霉菌细胞分化过程,发育阶段划分的依据:卡那霉菌在摇瓶、一级种子罐、二级种子罐和发酵罐的不同培养条件下,有规律地进行了一系列的生活循环。在摇瓶、一级种子罐和二级种子罐内,各完成一个生活循环,在发酵罐内能完成三个生活循环。在每个生活循环中,又有规律地完成各个发育阶段。除摇瓶培养由于原始接种材料是从斜面培养转入浸没培养,存在着一个生活循环中五个发育阶段外,一级种子罐、二级种子罐和发酵罐中的每一个生活循环,都只有三个发育阶段,但是由于培养基成份和培养条件不同,完成每一发育阶段的时间有所不同。不同发育阶段的菌丝细胞具有不同的特征和特性,细胞的内外结构不同,生化功能也不同,结构和功能间有一定的相关性。 相似文献
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毕赤酵母高密度表达重组猪胰岛素前体的研究 总被引:1,自引:0,他引:1
对摇瓶和50L罐上的重组菌毕赤酵母(Pichia pastoris)表达猪胰岛素前体(PIP)的发酵过程进行了研究。摇瓶发酵中,最佳诱导周期为60 h左右,诱导期甲醇的最佳加入量为每日2.0%~2.5%。50L发酵过程分为批发酵、补料和诱导表达3个阶段。生长期(批发酵和补料阶段)细胞干重与培养时间的关系可用模型y= 0.6525e~(0.1909t)来描述。在批发酵阶段和补料阶段,流加的氨水和甘油几乎全部用来合成菌体和维持,没有其他副产物产生。诱导表达阶段流加的氨水和甲醇分别约有80%和70%被菌体利用。将摇瓶与发酵罐的实验结果进行了比较,发现摇瓶发酵的限制因子很可能是溶氧,而罐发酵的限制因子为碳源,因此,将摇瓶实验的结果放大到发酵罐时调整了控制策略,加大了甲醇的补料速率,最终PIP浓度达到1.72g/L。 相似文献
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【背景】林可霉素是一种在临床应用上占有重要地位的林可酰胺类抗生素,关于调控发酵生产中三级种子罐相关参数优化林可霉素发酵工艺的研究较少。【目的】优化林可霉素发酵工艺,提高林可霉素发酵效价及市场竞争力。【方法】对林可霉素生产中三级种子罐的培养基和接种量及三级种子移种菌龄进行优化。【结果】在三级种子罐培养基中葡萄糖、淀粉、玉米浆、黄豆饼粉和硫酸铵浓度分别为64.0、5.0、15.0、14.5和3.5g/L,三级种子罐接种量为25%及三级种子移种菌龄为60h的优化条件下,林可霉素四级发酵效价高达7883U/mL,比优化前效价提高了10%。【结论】对林可霉素生产中三级种子罐相关参数进行调控,初步优化了林可霉素发酵工艺,提高了发酵效价,为优化林可霉素发酵工艺提供了新思路。 相似文献
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产酮产碱菌E54可利用D-葡萄糖发酵产生2-酮基-葡萄糖酸钙,再经甲酯化和化学转化而得到D-异抗坏血酸钢。通过大量摇瓶和罐上试验,进一步优化了培养基组分,改进了发酵条件,并采用批加工艺提高了投糖浓度。菌株在5L罐中发酵周期36h左右,利用D-葡萄糖浓度18~25g/100ml,充分子转化率达90%左在;在147L罐中发酵周期40h左右,利用D-葡萄糖浓度18~25g/100ml,充分子转化率达90%左右。 相似文献
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产酮产碱菌E54可利用D-葡萄糖发酵产生2-酮基-葡萄糖酸钙,再经甲酯化和化学转化而得到D-异抗坏血酸钢。通过大量摇瓶和罐上试验,进一步优化了培养基组分,改进了发酵条件,并采用批加工艺提高了投糖浓度。菌株在5L罐中发酵周期36h左右,利用D-葡萄糖浓度18~25g/100ml,充分子转化率达90%左在;在147L罐中发酵周期40h左右,利用D-葡萄糖浓度18~25g/100ml,充分子转化率达90%左右。 相似文献
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高丁醇比丙酮丁醇梭菌的选育与应用 总被引:6,自引:0,他引:6
设计了专一性分离方法,从土样中分离了多株能产生溶剂的梭苗,经多次单细胞分离、纯化,再经亚硝基胍和甲基磺酸乙酯诱变和抗性筛选,获得几株高丁醇的丙酮丁醇梭菌。对高产菌株的性状稳定性、发酵过程、混合原料应用、温度的影响进行了研究。结果证明菌株性状稳定,丁醇产量为总溶剂的70%;过程为典型的丙酮丁醇发酵,对温度可耐受到39-40℃;能利用玉米和薯干,玉米和高梁进行正常发酵。菌株已在百吨生产罐,连续应用一年 相似文献
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Export of maltose-binding protein species with altered charge distribution surrounding the signal peptide hydrophobic core in Escherichia coli cells harboring prl suppressor mutations.
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It is believed that one or more basic residues at the extreme amino terminus of precursor proteins and the lack of a net positive charge immediately following the signal peptide act as topological determinants that promote the insertion of the signal peptide hydrophobic core into the cytoplasmic membrane of Escherichia coli cells with the correct orientation required to initiate the protein export process. The export efficiency of precursor maltose-binding protein (pre-MBP) was found to decrease progressively as the net charge in the early mature region was increased systematically from 0 to +4. This inhibitory effect could be further exacerbated by reducing the net charge in the signal peptide to below 0. One such MBP species, designated MBP-3/+3 and having a net charge of -3 in the signal peptide and +3 in the early mature region, was totally export defective. Revertants in which MBP-3/+3 export was restored were found to harbor mutations in the prlA (secY) gene, encoding a key component of the E. coli protein export machinery. One such mutation, prlA666, was extensively characterized and shown to be a particularly strong suppressor of a variety of MBP export defects. Export of MBP-3/+3 and other MBP species with charge alterations in the early mature region also was substantially improved in E. coli cells harboring certain other prlA mutations originally selected as extragenic suppressors of signal sequence mutations altering the hydrophobic core of the LamB or MBP signal peptide. In addition, the enzymatic activity of alkaline phosphatase (PhoA) fused to a predicted cytoplasmic domain of an integral membrane protein (UhpT) increased significantly in cells harboring prlA666. These results suggest a role for PrlA/SecY in determining the orientation of signal peptides and possibly other membrane-spanning protein domains in the cytoplasmic membrane. 相似文献
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《Journal of Biomedical Engineering》1993,15(6):469-473
A nonlinear neural network classifier was applied to noninvasive acoustic detection of coronary artery disease; the classifier included a feature vector, derived from diastolic heart sounds, and a multi-layered network trained by the backpropagation. The feature vector is based on the linear prediction coefficients of the autoregressive method after an adaptive line enhancement method was used as the input pattern to the neural network. One hundred and twelve recordings (70 abnormal, 42 normal) were studied and the network was trained on a randomly chosen set of six abnormal and six normal patients. It was tested on a database consisting of 100 recordings to which it had not been exposed. The network correctly identified 50 of the 64 patients with coronary artery disease and 32 of the 36 patients without any coronary artery occlusions. These results showed that this neural network is capable of distinguishing normal patients from abnormal patients. In addition, the diagnostic capability of this approach is much better than any other available noninvasive approach. 相似文献
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将山东省招远市一慢电泳异常血红蛋白( Hb)先证者血及正常人血分离纯化出珠蛋白,脲处理解链,再层析分离并纯化出正常及异常 β链.经胰蛋白酶水解,所得肽片段用 H P L C 分出酶解物中异常肽,此肽经氨基酸组成及顺序测定,表明它同于正常 β链的十九肽 β41→59;异常肽不被 C N Br 作用,将它与正常十九肽通过质谱仪测定质荷比.结果说明异常肽的 β55 M et转变为亚砜型的 β55 M et· O,这转变是此异常 Hb 变异的一级结构基础. 相似文献
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Optimizing the affinity and specificity of ligand binding with the inclusion of solvation effect
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Solvation effect is an important factor for protein–ligand binding in aqueous water. Previous scoring function of protein–ligand interactions rarely incorporates the solvation model into the quantification of protein–ligand interactions, mainly due to the immense computational cost, especially in the structure‐based virtual screening, and nontransferable application of independently optimized atomic solvation parameters. In order to overcome these barriers, we effectively combine knowledge‐based atom–pair potentials and the atomic solvation energy of charge‐independent implicit solvent model in the optimization of binding affinity and specificity. The resulting scoring functions with optimized atomic solvation parameters is named as specificity and affinity with solvation effect (SPA‐SE). The performance of SPA‐SE is evaluated and compared to 20 other scoring functions, as well as SPA. The comparative results show that SPA‐SE outperforms all other scoring functions in binding affinity prediction and “native” pose identification. Our optimization validates that solvation effect is an important regulator to the stability and specificity of protein–ligand binding. The development strategy of SPA‐SE sets an example for other scoring function to account for the solvation effect in biomolecular recognitions. Proteins 2015; 83:1632–1642. © 2015 Wiley Periodicals, Inc. 相似文献
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The role of drift and diffusion as driving forces for charge carrier extraction in flat heterojunction organic solar cells is examined at the example of devices showing intentional S‐shaped current–voltage (J‐V) characteristics. Since these kinks are related to energy barriers causing a redistribution of the electric field and charge carrier density gradients, they are suitable for studying the limits of charge extraction. The dynamics of this redistribution process are experimentally monitored via transient photocurrents, where the current response on square pulses of light is measured in the μs to ms regime. In combination with drift‐diffusion simulation data, we demonstrate a pile‐up of charge carriers at extraction barriers and a high contribution of diffusion to photocurrent in the case of injection barriers. Both types of barrier lead to S‐kinks in the J‐V curve and can be distinguished from each other and from other reasons for S‐kinks (e.g. imbalanced mobilities) by applying the presented approach. Furthermore, it is also helpful to investigate the driving forces for charge extraction in devices without S‐shaped J‐V curve close to open circuit to evaluate whether their electrodes are optimized. 相似文献
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The uncA gene codes for the alpha-subunit of the adenosine triphosphatase of Escherichia coli. Electrophoretic analysis of uncA mutant strains.
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A E Senior J A Downie G B Cox F Gibson L Langman D R Fayle 《The Biochemical journal》1979,180(1):103-109
Four mutant strains of Escherichia coli which lack membrane-bound adenosine triphosphatase activity were shown by genetic-complementation tests to carry mutations in the uncA gene. A soluble inactive F1-ATPase aggregate was released from the membranes of three of the uncA mutant strains by low-ionic-strength washing, and purified by procedures developed for the purification of F1-ATPase from normal strains. Analysis of the subunit structure by two-dimensional gel electrophoresis indicated that the F1-ATPase in strains carrying the uncA401 or uncA453 alleles had a subunit structure indistinguishable from normal F1-ATPase. In contrast, the F1-ATPase from the strain carrying the uncA447 allele contained an alpha-subunit of normal molecular weight, but abnormal net charge. Membranes from strains carrying the uncA450 allele did not have F1-ATPase aggregates that could be solubilized by low-ionic-strength washing. However, a partial dipolid strain carrying both the uncA+ and uncA450 alleles formed an active F1-ATPase aggregate which could be solubilized by low-ionic-strength washing of the membranes and which contained two types of alpha-subunit, one of which was normal and the other had abnormal net charge. It is concluded that the uncA gene codes for the alpha-subunit of the adenosine triphosphatase. 相似文献
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利用The Cancer Genome Atlas和Genotype-Tissue Expression公共数据检索收集胃癌(Gastric cancer, GC)基因表达数据集,筛选与早期胃癌密切相关的基因并构建胃癌早期诊断预测模型。运用Deseq2软件包筛选早期胃癌差异基因,并对差异基因进行GO和KEGG富集分析。通过STRING数据库建立其蛋白质相互作用网络并利用Cytoscape软件提取关键子网得到候选关键基因,进一步利用MedCalc软件确认胃癌早期诊断关键基因。根据筛选得到的10个关键基因构建基于支持向量机、随机森林、朴素贝叶斯、K-近邻、极限梯度提升和自适应提升等六种算法的胃癌早期诊断预测模型,依据ROC曲线和准确率等评价指标对各个分类器模型进行评估,通过独立测试集验证得到极致梯度提升诊断预测模型为最优模型。本研究成果为提高结胃癌早期诊断的研究提供了新的思路和方法。 相似文献
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C. P. Werner M. J. Kearsey T. C. Crowther B. D. Dowker 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(4):507-512
Summary A design and model are presented to allow the prediction, in early generations, of the mean and distribution of recombinant inbred lines derived from a cross between two parental populations or partially inbred lines. The procedure has been tested in autumn-sown onions (in the UK) using a wide cross between the openpollinated Japanese cultivar, Senshyu, and a partially inbred line derived from the European cultivar, Rawska. The early generations used for prediction included the first self-pollinated generation of the two parental populations and the F3 generation produced from the hybrid population. The predictions were tested by reference to the field performance of a random array of inbred lines, which were produced by single-seed descent (SSD) and had been selfed for three generations. The early generations, used for prediction, and a sample of SSD lines were raised alongside each other in each of two seasons. Within each season, good agreement was found between the predicted and observed performance of the recombinant inbred lines for three characters — yield, quality and maturity. This is used as evidence of the validity of the genetical model and the assumptions made. The effects of genotype x environment interactions prevented predictions made in one season being reliably applied to those made in the other and, therefore, reduce the attraction of this type of prediction study to the plant breeder. 相似文献