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氯代烃(Chlorinated hydrocarbons,CAHs)污染遍布全球,其三致效应和遗传毒性对人类健康和生态环境构成重大威胁。CAHs异养同化具有降解彻底、无二次污染和降解效率高的特点,全面认识CAHs异养同化过程,对于强化和应用异养同化降解,扩大CAHs的修复途径具有重要的推动作用。文中首先分析了微生物细胞异养同化降解CAHs主要方式,阐述了异养同化的两大优势;针对CAHs异养同化的研究现状进行了系统性的总结,明确了可发生异养同化作用的CAHs种类及特征;基于氯代烷烃、氯代烯烃和氯代芳烃分类,概述了异养同化微生物的主要菌属及代谢特征;针对典型氯代烃,系统分析了参与代谢过程关键酶及特征基因,归纳了异养同化代谢途径;最后,根据当前研究现状对异养同化研究存在的问题进行了综述并对未来的发展方向进行了展望。 相似文献
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明晰氯代烃在复杂污染体系中的生物转化机制对强化污染物原位生物修复有重要意义。填埋场属典型复合污染场地,本文对不同地区填埋场填埋气中氯代烃种类、含量和其在覆盖层中的降解情况进行统计分析,发现填埋气中主要包括氯代烷烃和氯代烯烃两大类污染物,其浓度分别为0.20–32.45μg/m~3和0.50–32.45μg/m~3;覆盖土对氯代烃降解速率随着氯原子取代的增多而降低。基于覆盖层中微生物种类多、生长底物复杂多样和不同梯度氧气含量差异等特点,总结得出氯代烃在覆盖土中的降解途径主要是好氧共代谢、直接氧化和厌氧还原脱氯;并基于不同工况特点构建了氯代烃在填埋场覆盖层底部扩散至大气界面过程的生物转化机制模型。最后就复杂环境体系中氯代烃类污染物的去除进行了展望。 相似文献
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厌氧微生物降解多环芳烃研究进展 总被引:2,自引:0,他引:2
多环芳烃(PAHs)是一类普遍存在于环境介质中的难降解有机污染物,相对于好氧微生物降解PAHs的研究,厌氧微生物降解PAHs的研究则相对较少.本文从厌氧微生物降解PAHs的研究背景,厌氧降解微生物的特点和不同厌氧降解还原反应体系的角度综述了厌氧微生物降解PAHs的概况;结合厌氧微生物降解萘和菲转化途径的介绍,推断了其降解机制的内在原因;同时通过总结影响厌氧微生物降解PAHs的主要因素(包括:PAHs的生物可利用性、外源营养物质的添加、外源电子受体的添加、特定厌氧降解菌的筛选强化和部分环境因素等),指出了制约降解进程的潜在限制因子;并对厌氧微生物降解PAHs研究目前存在的问题和未来的发展方向作了简述与展望. 相似文献
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微生物降解是环境中农药消解的重要因素,分离筛选纯培养的农药降解微生物并阐述其降解机制为微生物修复环境的应用提供重要的菌株资源和理论依据。本文简述了广泛使用的8类除草剂(包括有机磷类、磺酰脲类、氯乙酰胺类、均三嗪类、芳氧基苯氧基丙酸酯类、苯氧乙酸类、二硝基苯胺类和硫代氨基甲酸酯类除草剂)的降解微生物资源及其降解途径和降解基因的研究进展,并分析了目前除草剂污染修复存在的问题及未来的发展方向。 相似文献
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生物胺是存在于发酵食品和酒精饮料中的潜在胺类危害物。如果人体摄入过量的生物胺,则会引起呼吸困难、呕吐和发烧等过敏反应。生物胺降解酶是通过将生物胺氧化成醛类物质来实现降解生物胺的一类酶。目前发现的具有降解生物胺能力的酶主要包括胺氧化酶、胺脱氢酶和多铜氧化酶。本文详细阐述了这3类主要生物胺降解酶的催化机理、底物特异性、酶学性质、应用特性和它们对生物胺的降解效果,归纳和总结了生物胺降解酶的异源表达和分子改造的研究进展,并对生物胺降解酶在基因挖掘、分子改造和表达等方面的研究趋势进行了展望,以期为研究和开发食品中生物胺的酶法降解策略提供参考。 相似文献
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多环芳烃(polycyclic aromatic hydrocarbon,PAHs)是一类对环境有严重危害的持久性有机污染物。具有高生物富集性、致癌性、致毒性和难降解性,修复治理PAHs污染环境备受国内外政府及学者的关注。目前主要采用物理、化学以及生物方法对多环芳烃污染的土壤和水体进行修复。其中生物修复是一种高效、经济和生态可承受的环保技术,具有成本低、无二次污染等优点。本文从植物修复、微生物修复以及植物-微生物联合修复方面,阐述了国内外生物修复PAHs污染的最新研究进展。指出了生物修复PAHs污染环境需要进一步解决的问题,并对未来发展趋势进行了展望。 相似文献
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随着国内外禁塑令和限塑令的升级,以聚乳酸(polylactic acid, PLA)为代表的生物基塑料成为传统石油基塑料市场的主要替代品,备受产业界的青睐。然而,公众对生物基塑料的认识仍存在诸多误解。事实上,生物基塑料的降解需要在特定条件下才能实现,泄入到自然环境中同样难以降解,会对人体、生物多样性和生态系统功能造成危害,这与传统石油基塑料相似。近年来,随着我国PLA产能和市场规模不断的提高,亟需进一步加强对PLA等生物基塑料降解性能的认识,挖掘PLA生物降解资源,关注和研究生物基塑料回收处理模式。基于上述背景,本文首先介绍了PLA塑料的性质及合成方式,以及PLA塑料的产业化与市场规模;其次,对目前聚乳酸塑料微生物与酶法降解的研究进展进行了综述,并对其生物降解机制进行了探讨;最后,提出了微生物原位处理和酶法闭环回收两种聚乳酸塑料废弃物生物处置方法,并对PLA生物基塑料的发展前景和趋势进行了展望。 相似文献
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We present an ecological framework for considering ecosystem degradation and restoration, particularly in rangelands and arid environments. The framework is a synthesis of three conceptual models previously developed by several rangeland and restoration ecologists. We focus first on distinctions and connections between structural and functional components of rangeland ecosystems and then on distinctions and connections between biotic and abiotic components of the ecosystem. We next show that the structural/functional and biotic/abiotic distinctions can be integrated with a stepwise, positive feedback model of degradation to help explain degradation processes and restoration approaches. Finally, we relate those concepts to a threshold model of rangeland degradation. By establishing the conceptual links among these different models, this synthesis provides a broader, more integrated framework for thinking about the dynamics involved in rangeland degradation and restoration. We conclude by presenting some approaches to restoration that are motivated by the suite of concepts that are brought together in the framework. 相似文献
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Nancy Ockendon David J. Baker Jamie A. Carr Elizabeth C. White Rosamunde E. A. Almond Tatsuya Amano Esther Bertram Richard B. Bradbury Cassie Bradley Stuart H. M. Butchart Nathalie Doswald Wendy Foden David J. C. Gill Rhys E. Green William J. Sutherland Edmund V. J. Tanner James W. Pearce‐Higgins 《Global Change Biology》2014,20(7):2221-2229
Shifts in species' distribution and abundance in response to climate change have been well documented, but the underpinning processes are still poorly understood. We present the results of a systematic literature review and meta‐analysis investigating the frequency and importance of different mechanisms by which climate has impacted natural populations. Most studies were from temperate latitudes of North America and Europe; almost half investigated bird populations. We found significantly greater support for indirect, biotic mechanisms than direct, abiotic mechanisms as mediators of the impact of climate on populations. In addition, biotic effects tended to have greater support than abiotic factors in studies of species from higher trophic levels. For primary consumers, the impact of climate was equally mediated by biotic and abiotic mechanisms, whereas for higher level consumers the mechanisms were most frequently biotic, such as predation or food availability. Biotic mechanisms were more frequently supported in studies that reported a directional trend in climate than in studies with no such climatic change, although sample sizes for this comparison were small. We call for more mechanistic studies of climate change impacts on populations, particularly in tropical systems. 相似文献
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木葡聚糖(XyG)是一种存在于所有陆生植物细胞壁中的基质多糖, 是双子叶植物初生细胞壁中含量(20%-25%, w/w)最丰富的半纤维素成分。作为细胞壁的组分, XyG不仅与植物的生长发育密切相关, 还在植物抵抗各种生物和非生物逆境过程中发挥重要作用。XyG代谢相关基因主要通过改变植物细胞壁的组成以及对细胞壁进行重排进而改变细胞壁的弹性/硬度等特性, 影响植物的抗逆性。XyG及其寡糖也可能作为信号分子, 或与其它信号分子协同作用应对逆境胁迫。该文概述了XyG的结构与类型及参与XyG生物合成与降解的相关基因, 重点阐述XyG相关基因应答生物和非生物胁迫的作用机制。 相似文献
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Biotic degradation at night,abiotic degradation at day: positive feedbacks on litter decomposition in drylands
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Daniel Gliksman Ana Rey Ron Seligmann Rita Dumbur Or Sperling Yael Navon Sabine Haenel Paolo De Angelis John A. Arnone III José M. Grünzweig 《Global Change Biology》2017,23(4):1564-1574
The arid and semi‐arid drylands of the world are increasingly recognized for their role in the terrestrial net carbon dioxide (CO2) uptake, which depends largely on plant litter decomposition and the subsequent release of CO2 back to the atmosphere. Observed decomposition rates in drylands are higher than predictions by biogeochemical models, which are traditionally based on microbial (biotic) degradation enabled by precipitation as the main mechanism of litter decomposition. Consequently, recent research in drylands has focused on abiotic mechanisms, mainly photochemical and thermal degradation, but they only partly explain litter decomposition under dry conditions, suggesting the operation of an additional mechanism. Here we show that in the absence of precipitation, absorption of dew and water vapor by litter in the field enables microbial degradation at night. By experimentally manipulating solar irradiance and nighttime air humidity, we estimated that most of the litter CO2 efflux and decay occurring in the dry season was due to nighttime microbial degradation, with considerable additional contributions from photochemical and thermal degradation during the daytime. In a complementary study, at three sites across the Mediterranean Basin, litter CO2 efflux was largely explained by litter moisture driving microbial degradation and ultraviolet radiation driving photodegradation. We further observed mutual enhancement of microbial activity and photodegradation at a daily scale. Identifying the interplay of decay mechanisms enhances our understanding of carbon turnover in drylands, which should improve the predictions of the long‐term trend of global carbon sequestration. 相似文献
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Plant growth response to direct and indirect temperature effects varies by vegetation type and elevation in a subarctic tundra
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Jonathan R. De Long Paul Kardol Maja K. Sundqvist G. F. Veen David A. Wardle 《Oikos》2015,124(6):772-783
There has been growing recent use of elevational gradients as tools for assessing effects of temperature changes on vegetation properties, because these gradients enable temperature effects to be considered over larger spatial and temporal scales than is possible through conventional experiments. While many studies have explored the direct effects of temperature, the indirect effects of temperature through its long‐term influence on soil abiotic or biotic properties remain essentially unexplored. We performed two climate chamber experiments using soils from a subarctic elevational gradient in Abisko, Sweden to investigate the direct effects of temperature, and indirect effects of temperature via soil legacies, on growth of two grass species. The soils were collected from each of two vegetation types (heath, dominated by dwarf shrubs, and meadow, dominated by graminoids and herbs) at each of three elevations. We found that plants responded to both the direct effect of temperature and its indirect effect via soil legacies, and that direct and indirect effects were largely decoupled. Vegetation type was a major determinant of plant responses to both the direct and indirect effects of temperature; responses to soils from increasing elevation were stronger and showed a more linear decline for meadow than for heath soils. The influence of soil biota on plant growth was independent of elevation, with a positive influence across all elevations regardless of soil origin for meadow soils but not for heath soils. Taken together, this means that responses of plant growth to soil legacy effects of temperature across the elevational gradient were driven primarily by soil abiotic, and not biotic, factors. These findings emphasize that vegetation type is a strong determinant of how temperature variation across elevational gradients impacts on plant growth, and highlight the need for considering both direct and indirect effects of temperature on plant responses to future climate change. 相似文献
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Members of the Pathogenesis Related (PR) 10 protein family have been
identified in a variety of plant species and a wide range of functions ranging from
defense to growth and development has been attributed to them. PR10 protein
possesses ribonuclease (RNase) activity, interacts with phytohormones, involved
in hormone-mediated signalling, afforded protection against various phytopathogenic fungi, bacteria, and viruses particularly in response to biotic and abiotic
stresses. The resistance mechanism of PR10 protein may include activation of
defense signalling pathways through possible interacting proteins involved in
mediating responses to pathogens, degradation of RNA of the invading pathogens. Moreover, several morphological changes have been shown to accompany
the enhanced abiotic stress tolerance. In this review, the possible mechanism of
action of PR10 protein against biotic and abiotic stress has been discussed.
Furthermore, our findings also confirmed that the in vivo Nitric oxide (NO) is
essential for most of environmental abiotic stresses and disease resistance against
pathogen infection. The proper level of NO may be necessary and beneficial, not
only in plant response to the environmental abiotic stress, but also to biotic stress.
The updated information on this interesting group of proteins will be useful in
future research to develop multiple stress tolerance in plants. 相似文献