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耐有机溶剂微生物在生物燃料生产、全细胞催化、酶制剂的开发和生物修复等领域具有非常重要的作用。该文简要介绍了耐有机溶剂微生物及其耐受机制,并从基因过表达、基因敲除和全局转录机制三个方面总结了增强微生物有机溶剂耐受性的方法。通过对耐有机溶剂微生物应用的局限性进行分析,认为未来研究中应注重将微生物耐受表型和具体利用相结合,达到有机溶剂耐受和实际产出的最佳平衡状态,为耐有机溶剂工程菌的改造和选育提供参考。 相似文献
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细菌的有机溶剂耐受机制 总被引:3,自引:0,他引:3
有机溶剂有严重破坏微生物正常生理功能的毒害作用,但是研究工作者发现有些细菌能够在较高有机溶剂浓度下依赖独特的耐受机制得以生存,这种机制的发现大大鼓舞了工业菌尤其是溶剂生产菌和毒性有机物降解菌的工业适应性改造研究。以下概述了有机溶剂对细胞毒性作用机制,并在根据参数logP衡量不同溶剂对细胞的毒性程度的基础上,重点总结了溶剂耐受菌耐受有机溶剂的机制,即膜上顺反异构、增加饱和脂肪酸的比率、改变极性头部、外膜的生理变化、细胞的形态变化、胞内溶剂的降解和泵出等,结合本课题组在筛选溶剂耐受菌株和提高现有菌株溶剂耐受性研究方面的经验,希望对重要工业微生物溶剂耐受相关的生理功能进行更深入地研究,提高微生物的工业适应性。 相似文献
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溶剂稳定性蛋白酶产生菌的筛选和鉴定 总被引:3,自引:0,他引:3
自油污土样等样品中分离获得一株具有产胞外溶剂稳定性蛋白酶的耐有机溶剂极端微生物,经BIOLOG系统鉴定及16S rDNA序列(GenBank,EF105377)分析,该菌株为Bacillus licheniformis YP1。该菌株能耐受中浓度盐、强碱性环境(pH12)及多种不同浓度的有机溶剂,但对多种抗生素敏感。在YP1产蛋白酶发酵过程中添加各种有机溶剂结果表明,丙酮虽抑制了菌体生物量的生长却促进了单位菌体的蛋白酶分泌,而长链烷醇如辛醇、十二醇等能强烈抑制该蛋白酶的分泌。该菌株所产蛋白酶经11种50%(V/V)有机溶剂处理后均能保留高活力。该溶剂稳定性蛋白酶在有机相生物催化等领域具有良好的应用前景。 相似文献
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环境微生物是维持生态圈中能量和物质循环的重要因素之一,在各种污染物和有害物质的降解等方面发挥着重要作用,在进行能源生产和可再生利用等研究领域具有潜在应用价值.在超过150种被破译的非致病微生物基因组中,绝大多数是环境和工业细菌.随着新一代测序技术的投入使用和元基因组学方法的出现,国际上的微生物基因组方面的工作进入了高通量和高产出的阶段.我国已经完成全基因组测序的7株环境细菌中涵盖了嗜高温、嗜酸、耐高压、耐低压等各种极端环境微生物,研究人员从中发现了众多与环境和工业应用密切相关的代谢途径、遗传功能和生物酶,目前,国内多家单位相继启动了元基因组计划,必将使我国在环境和工业微生物基因组研究领域取得一大批原创成果. 相似文献
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极端微生物是一类能够适应特殊环境的微生物,相关功能蛋白在其适应极端环境过程中发挥着重要作用,探索极端微生物的特性及其相关的功能蛋白有助于深入了解生命的起源与进化,为蛋白酶在工业领域的应用提供一定理论依据。现概述耐辐射球菌、嗜盐菌、嗜热菌、嗜酸菌和嗜碱菌、嗜冷菌、嗜压菌的特性及其相关的功能蛋白质,从蛋白质水平阐述极端微生物对极端环境的适应机制。 相似文献
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耐有机溶剂脂肪酶的研究进展 总被引:1,自引:1,他引:0
脂肪酶是一种重要的酶,在有机介质中脂肪酶能催化某些特定的化学反应。获得具有较高催化活性的耐有机溶剂脂肪酶具有重要的价值。该文概述了一些具有代表性的耐有机溶剂脂肪酶,介绍了耐有机溶剂脂肪酶的特性和应用,并对耐有机溶剂脂肪酶的筛选途径和分子改造方法进行了分析。今后有机溶剂耐受性脂肪酶的研究将集中在酶的利用、微生物筛选、脂肪酶表征和基因克隆、酶的分子改造等方面。 相似文献
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有机溶剂中固定化脂肪酶催化硅醇的酯化反应 总被引:4,自引:0,他引:4
固定化Mucor miehei脂肪酶可催化有机硅醇和脂肪酸的酯化反应.对固定化酶用量、脂肪酸链长、不同有机硅醇底物、有机溶剂极性和水含量等影响因素进行了初步研究. 相似文献
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Enzyme catalysis evolved in an aqueous environment. The influence of solvent dynamics on catalysis is, however, currently poorly understood and usually neglected. The study of water dynamics in enzymes and the associated thermodynamical consequences is highly complex and has involved computer simulations, nuclear magnetic resonance (NMR) experiments, and calorimetry. Water tunnels that connect the active site with the surrounding solvent are key to solvent displacement and dynamics. The protocol herein allows for the engineering of these motifs for water transport, which affects specificity, activity and thermodynamics. By providing a biophysical framework founded on theory and experiments, the method presented herein can be used by researchers without previous expertise in computer modeling or biophysical chemistry. The method will advance our understanding of enzyme catalysis on the molecular level by measuring the enthalpic and entropic changes associated with catalysis by enzyme variants with obstructed water tunnels. The protocol can be used for the study of membrane-bound enzymes and other complex systems. This will enhance our understanding of the importance of solvent reorganization in catalysis as well as provide new catalytic strategies in protein design and engineering. 相似文献
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Heipieper HJ Neumann G Cornelissen S Meinhardt F 《Applied microbiology and biotechnology》2007,74(5):961-973
Product removal from aqueous media poses a challenge in biotechnological whole-cell biotransformation processes in which substrates
and/or products may have toxic effects. The assignment of an additional liquid solvent phase provides a solution, as it facilitates
in situ product recovery from aqueous media. In such two-phase systems, toxic substrates and products are present in the aqueous
phase in tolerable but still bioavailable amounts. As a matter of course, adequate organic solvents have to possess hydrophobicity
properties akin to substrates and products of interest, which in turn involves intrinsic toxicity of the solvents used. The
employment of bacteria being able to adapt to otherwise toxic solvents helps to overcome the problem. Adaptive mechanisms
enabling such solvent tolerant bacteria to survive and grow in the presence of toxic solvents generally involve either modification
of the membrane and cell surface properties, changes in the overall energy status, or the activation and/or induction of active
transport systems for extruding solvents from membranes into the environment. It is anticipated that the biotechnological
production of a number of important fine chemicals in amounts sufficient to compete economically with chemical syntheses will
soon be possible by making use of solvent-tolerant microorganisms. 相似文献
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Ruijssenaars HJ Sperling EM Wiegerinck PH Brands FT Wery J de Bont JA 《Journal of biotechnology》2007,131(2):205-208
A steroid 15beta-hydroxylating whole-cell solvent tolerant biocatalyst was constructed by expressing the Bacillus megaterium steroid hydroxylase CYP106A2 in the solvent tolerant Pseudomonas putida S12. Testosterone hydroxylation was improved by a factor 16 by co-expressing Fer, a putative Fe-S protein from Bacillus subtilis. In addition, the specificity for 15beta-hydroxylation was improved by mutating threonine residue 248 of CYP106A2 into valine. These new insights provide the basis for an optimized whole-cell steroid-hydroxylating biocatalyst that can be applied with an organic solvent phase. 相似文献
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非水相酶催化是酶工程研究热点之一。本文介绍了来自C.cylindracea的脂肪酶催化有机硅醇和脂肪酸的酯化反应。该酶可催化有机硅醇与脂肪酸的酯化反应,并对不同链长的脂肪酸底物、有机溶剂极性及水含量等进行了初步研究。 相似文献
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Oxidoreductases catalyze a large variety of regio-, stereo-, and chemoselective hydrocarbon oxyfunctionalizations, reactions, which are important in industrial organic synthesis but difficult to achieve by chemical means. This review summarizes process implementation aspects for the in vivo application of the especially versatile enzyme class of oxygenases, capable of specifically introducing oxygen from molecular oxygen into a large range of organic molecules. Critical issues such as reaching high enzyme activity and specificity, product degradation, cofactor recycling, reactant toxicity, and substrate and oxygen mass transfer can be overcome by biochemical process engineering and biocatalyst engineering. Both strategies provide a growing toolset to facilitate process implementation, optimization, and scale-up. Major advances were achieved via heterologous overexpression of oxygenase genes, directed evolution, metabolic engineering, and in situ product removal. Process examples from industry and academia show that the combined use of different concepts enables efficient oxygenase-based whole-cell catalysis of various commercially interesting reactions such as the biosynthesis of chiral compounds, the specific oxyfunctionalization of complex molecules, and also the synthesis of medium-priced chemicals. Better understanding of the cell metabolism and future developments in both biocatalyst and bioprocess engineering are expected to promote the implementation of many and various industrial biooxidation processes. 相似文献
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Role of the Multidrug Efflux Systems of Pseudomonas aeruginosa in Organic Solvent Tolerance 总被引:6,自引:0,他引:6 下载免费PDF全文
Multidrug efflux pumps with a broad substrate specificity make a major contribution to intrinsic and acquired multiple antibiotic resistance in Pseudomonas aeruginosa. Using genetically defined efflux pump mutants, we investigated the involvement of the three known efflux systems, MexA-MexB-OprM, MexC-MexD-OprJ, and MexE-MexF-OprN, in organic solvent tolerance in this organism. Our results showed that all three systems are capable of providing some level of tolerance to organic solvents such as n-hexane and p-xylene. Expression of MexAB-OprM was correlated with the highest levels of tolerance, and indeed, this efflux system was a major contributor to the intrinsic solvent tolerance of P. aeruginosa. Intrinsic organic solvent tolerance was compromised by a protonophore, indicating that it is substantially energy dependent. These data suggest that the efflux of organic solvents is a factor in the tolerance of P. aeruginosa to these compounds and that the multidrug efflux systems of this organism can accommodate organic solvents, as well as antibiotics. 相似文献
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Segura A Molina L Fillet S Krell T Bernal P Muñoz-Rojas J Ramos JL 《Current opinion in biotechnology》2012,23(3):415-421
Bacteria have been found in all niches explored on Earth, their ubiquity derives from their enormous metabolic diversity and their capacity to adapt to changes in the environment. Some bacterial strains are able to thrive in the presence of high concentrations of toxic organic chemicals, such as aromatic compounds, aliphatic alcohols and solvents. The extrusion of these toxic compounds from the cell to the external medium represents the most relevant aspect in the solvent tolerance of bacteria, however, solvent tolerance is a multifactorial process that involves a wide range of genetic and physiological changes to overcome solvent damage. These additional elements include reduced membrane permeabilization, implementation of a stress response programme, and in some cases degradation of the toxic compound. We discuss the recent advances in our understanding of the mechanisms involved in solvent tolerance. 相似文献