提高微生物抗逆性技术的研究进展

微生物体内存在多种抗逆基因或机制,这些机制的发现为定向提高微生物的抗逆性奠定了基础。提高微生物抗逆性的技术主要有过表达抗逆基因,长期适应性进化,genome shuffling(基因组改组)和异源表达抗逆基因等。利用这几种技术增强微生物的抗逆性,在以微生物为主的工业生产和环境污染物降解方面有着广阔的应用前景。     

分子生物学技术在土壤生物修复中的应用及展望

综述了分子生物学技术包括环境微生物群落降解基因分析、16S rRNA序列分析技术以及荧光原位杂交技术在生物修复技术中跟踪污染土壤中降解微生物行为、监测降解基因和微生物群落变化,揭示了其中的分子机制的应用现状,对各项技术应用中需要注意的问题进行了讨论并对其发展前景进行了展望。     

药用植物与根际微生物互作的研究进展

针对药用植物根际微生物的主要研究方法展开分析,包括微生物平板培养法、Biolog 法、磷脂脂肪酸法、分子生物学技术等,结合不同品种植物、不同生长时期、不同种植模式药用植物对根际微生物的影响,以及根际微生物对药用植物植物生长、抗病能力、抗逆能力、连作障碍、次生代谢产物的影响,通过研究药用植物与根际微生物互作机制,积累可靠的应用数据,为体系的优化完善提供可靠的数据支持。     

核糖核酸开关用于微生物细胞工厂的智能与精细调控

利用代谢工程与合成生物技术对细胞内复杂的代谢网络和调控网络进行重构和改造,以建立合成新化合物或提高目标产物产量的微生物细胞工厂是当今绿色化工技术发展的方向之一。微生物代谢途径的调控受环境和遗传的双重影响,细胞通过全局转录因子、信使分子和反馈抑制等方式响应环境变化来维持细胞的内稳态;同时细胞还受自身遗传基因线路的调控,在转录、翻译以及翻译后修饰过程中调控特定基因的表达。核糖核酸开关是一类调控基因线路表达的RNA元件,通过与金属离子、糖类衍生物、氨基酸、核酸衍生物以及辅酶等特异性配体结合发生的构象变化,从而启动或阻断mRNA的转录、翻译、拼接等过程来调控基因的表达。核糖核酸开关作为天然的生物感受器和效应器通过人工设计可成为微生物细胞工厂智能化和精细化调控的分子工具,并在化工、医药、环保、食品等领域得到广泛应用。     

动态转录调控微生物代谢途径研究进展

传统的微生物代谢工程主要是通过过表达或敲除关键基因来实现产物产量最大化,但会造成代谢流失衡,生产效能降低。而对微生物代谢途径进行动态调控可维持细胞生长,平衡代谢流,提高生产效率。本文根据信号分子的来源不同,将微生物在转录水平的动态调控分为两种：一种是在光、温度、化学诱导剂的外源信号刺激下,利用响应该信号的启动子等元件调控下游代谢途径的人工诱导动态调控;另一种为在胞内代谢物水平或细胞密度改变的内源信号感应下,利用启动子、转录因子、核糖核酸开关调节关键基因的细胞自主诱导动态调控。本文同时介绍了转录水平动态调控策略在微生物代谢工程中的应用实例,以期对代谢途径的多个基因实现连续动态表达以及适配表达,有效提高目标产物的产量。     

生物有机无机烟草专用肥生产技术总结

根据土壤养分状况并结合烟草需肥规律,开发出生物有机无机烟草专用肥,简要介绍了其生产方法。经大田试验、示范,结果表明生物有机无机烟草专用肥对提高烟叶产量、质量和增强烟草抗逆性均具有明显的效果,具有改土、抗逆、增产和提高烟草品质的综合优势。     

基于群体感应调控细菌生物膜形成研究进展

近些年来,许多研究都表明细菌等微生物之间存在群体感应现象(quorum sensing,QS)。许多细菌都能合成并分泌自诱导物质来调控基因的表达调控生物膜的形成,以此保证细菌在生长过程中适应新的环境。生物膜(biofilm)的存在与细菌的抗逆能力有很大的关联,基于驱散群体感应抑制生物膜的形成也成了目前的研究热点之一。本文主要综述了近几年在群体感应领域的一些发现,主要对细菌生物膜形成相关研究做了一些总结。     

微生物细胞工厂碳流调控进展

随着代谢工程技术的进步,越来越多微生物细胞工厂可用于化学品发酵生产。微生物细胞生产化学品具有生产条件温和、环境友好等优势,是实现化学品绿色可持续生产的重要手段。为了提高微生物细胞工厂的产量、得率和生产强度,传统代谢工程手段主要采用基因过表达或基因敲除方式增大目标代谢路径碳代谢流。然而由于代谢流调控精度不足,易导致细胞生产能力下降。本文主要针对微生物细胞工厂碳流调控中存在的瓶颈问题,从代谢流改造靶点选择、细胞生长与产物合成碳流平衡、副产物路径与产物合成竞争、产物合成效率强化四个角度,系统综述微生物细胞工厂碳代谢流调控的最新进展。并从高精度、仿生学、智能化、多任务、快响应调控工具的设计出发,对未来微生物细胞工厂的发展趋势进行展望。     

芳香族污染区的生物修复和监测研究的进展

生物除污可以修复被污染的土壤,这是因为微生物对有害有机化合物具有广泛的生物降解能力.生物除污及其功效方面研究的飞速发展,为检测各种微生物过程中相关关键基因的存在和表达提供了有效的分子学工具.综合分析被污染土壤中的各种基因在不同条件下的表达情况,揭示微生物的代谢情况,指示加速生物除污的环境变异.     

生物腐植酸复混肥料技术开发与应用

生物腐植酸复混肥料是采用预处理后的风化煤和普通无机复合肥为生产原料,经配料、造粒、干燥、筛分后再加入微生物制剂而成.该技术的实施可改变化肥特性,刺激植物生理代谢,改良土壤结构,增强作物抗逆性,提高作物品质.     

Genome-Wide Characterization and Abiotic Stresses Expression Analysis of Annexin Family Genes in Poplar

Poplar is an illustrious industrial woody plant with rapid growth, providing a range of materials, and having simple post-treatment. Various kinds of environmental stresses limit its output. Plant annexin (ANN) is a calcium-dependent phospholipid-binding protein involved in plant metabolism, growth and development, and cooperatively regulating drought resistance, salt tolerance, and various stress responses. However, the features of the PtANN gene family and different stress responses remain unknown in poplar. This study identified 12 PtANN genes in the P. trichocarpa whole-genome and PtANNs divided into three subfamilies based on the phylogenetic tree. The PtANNs clustered into the same clade shared similar gene structures and conserved motifs. The 12 PtANN genes were located in ten chromosomes, and segmental duplication events were illustrated as the main duplication method. Additionally, the PtANN4 homogenous with AtANN1 was detected localized in the cytoplasm and plasma membrane. In addition, expression levels of PtANNs were induced by multiple abiotic stresses, which indicated that PtANNs could widely participate in response to abiotic stress. These results revealed the molecular evolution of PtANNs and their profiles in response to abiotic stress.     

The Quorum Sensing Auto-Inducer 2 (AI-2) Stimulates Nitrogen Fixation and Favors Ethanol Production over Biomass Accumulation in Zymomonas mobilis

Autoinducer 2 (or AI-2) is one of the molecules used by bacteria to trigger the Quorum Sensing (QS) response, which activates expression of genes involved in a series of alternative mechanisms, when cells reach high population densities (including bioluminescence, motility, biofilm formation, stress resistance, and production of public goods, or pathogenicity factors, among others). Contrary to most autoinducers, AI-2 can induce QS responses in both Gram-negative and Gram-positive bacteria, and has been suggested to constitute a trans-specific system of bacterial communication, capable of affecting even bacteria that cannot produce this autoinducer. In this work, we demonstrate that the ethanologenic Gram-negative bacterium Zymomonas mobilis (a non-AI-2 producer) responds to exogenous AI-2 by modulating expression of genes involved in mechanisms typically associated with QS in other bacteria, such as motility, DNA repair, and nitrogen fixation. Interestingly, the metabolism of AI-2-induced Z. mobilis cells seems to favor ethanol production over biomass accumulation, probably as an adaptation to the high-energy demand of N₂ fixation. This opens the possibility of employing AI-2 during the industrial production of second-generation ethanol, as a way to boost N₂ fixation by these bacteria, which could reduce costs associated with the use of nitrogen-based fertilizers, without compromising ethanol production in industrial plants.     

Plant Mitogen-Activated Protein Kinase Cascades in Environmental Stresses

Due to global warming and population growth, plants need to rescue themselves, especially in unfavorable environments, to fulfill food requirements because they are sessile organisms. Stress signal sensing is a crucial step that determines the appropriate response which, ultimately, determines the survival of plants. As important signaling modules in eukaryotes, plant mitogen-activated protein kinase (MAPK) cascades play a key role in regulating responses to the following four major environmental stresses: high salinity, drought, extreme temperature and insect and pathogen infections. MAPK cascades are involved in responses to these environmental stresses by regulating the expression of related genes, plant hormone production and crosstalk with other environmental stresses. In this review, we describe recent major studies investigating MAPK-mediated environmental stress responses. We also highlight the diverse function of MAPK cascades in environmental stress. These findings help us understand the regulatory network of MAPKs under environmental stress and provide another strategy to improve stress resistance in crops to ensure food security.     

Hydrodynamische Belastbarkeit von Mikroorganismen

Hydrodynamic stress resistance of microorganisms . The production of microbial metabolites and the growth of microorganisms are affected by mechanical forces, such as occur on stirring, pumping, and aeration in industrial equipment. This paper considers the methods of investigation and typical experimental results. The sensitivity of the organisms depends upon the stability of the cell wall and upon its morphology. Raising the viscosity of nutrient solution increases the symptoms of damage at a given stirrer speed. In the case of methane-producing microorganisms, growth and product formation (methane production) are affected in the same manner. Physiological stress, induced for example by the absence of essential nutrients, proves additive to mechanical stress in its effect. It is suggested that the power dissipation per unit volume should be taken as a guide on scale-up or on transfer of experience gained with one kind of flow system (e. g. jet flow) to another (e. g. stirred tank).     

Mitochondrial adaptations to oxidative stress confer resistance to apoptosis in lymphoma cells

Acquired resistance to drugs commonly used for lymphoma treatment poses a significant barrier to improving lymphoma patient survival. Previous work with a lymphoma tissue culture model indicates that selection for resistance to oxidative stress confers resistance to chemotherapy-induced apoptosis. This suggests that adaptation to chronic oxidative stress can contribute to chemoresistance seen in lymphoma patients. Oxidative stress-resistant WEHI7.2 cell variants in a lymphoma tissue culture model exhibit a range of apoptosis sensitivities. We exploited this phenotype to test for mitochondrial changes affecting sensitivity to apoptosis in cells made resistant to oxidative stress. We identified impaired release of cytochrome c, and the intermembrane proteins adenylate kinase 2 and Smac/DIABLO, indicating inhibition of the pathway leading to permeabilization of the outer mitochondrial membrane. Blunting of a glucocorticoid-induced signal and intrinsic mitochondrial resistance to cytochrome c release contributed to both points of resistance. The level of Bcl-2 family members or a difference in Bim induction were not contributing factors. The extent of cardiolipin oxidation following dexamethasone treatment, however, did correlate with apoptosis resistance. The differences found in the variants were all proportionate to the degree of resistance to glucocorticoid treatment. We conclude that tolerance to oxidative stress leads to mitochondrial changes that confer resistance to apoptosis.