微生物降解有机污染物的研究进展

从降解菌的筛选及检测技术、新的降解菌种及其作用酶和代谢途径、污染物对降解菌的作用以及环境因素对降解菌的影响等方面介绍了微生物降有毒有机污染物的最新研究进展,预期该领域具有十分广阔的应用前景。     

降解强致癌性有机污染物的微生物

多氯联苯(PCB)是强致癌有机污染物之一,是潜在的致癌因子,这类化合物有209种之多,其中某些化合物具有类似二噁英(dioxin)的毒性如六氯联苯等。有些微生物对PCB有降解作用,如G^ 细菌(指革氏阳性菌)中有园红球菌(Rhodococcus globerulus)也称球状红球菌,还有红串红球菌(Rh．erythropolis)、芽孢杆菌(Bacillus sp．)野生株以及该两属其他未定名菌株均表现对PCB等的降解活力,     

微生物降解持久性有机污染物的研究进展与展望

持久性有机污染物（POPs）是伴随着人类工业化发展而产生的合成类污染物,具有高毒性、持久性、长迁移性和高生物富集性等特点,POPs污染物的微生物降解一直是环境科学与技术应用领域的研究热点。微生物降解技术修复POPs污染环境具有无二次污染、成本低、快速简便等优点,拥有广泛的应用前景。本文论述了各种POPs微生物分解代谢的最新研究进展,包括降解性微生物资源以及降解机制。此外,还讨论了计算生物学、合成生物学、基因组学等技术在POPs微生物降解中的潜力和应用,以期为环境中持久性有机污染物的修复提供参考。     

微生物菌剂在难降解有机污染治理的研究进展

大量的难降解有机污染物被排放到环境中,因其蓄积性、持久性和生物毒性,对人类健康和生态环境造成严重危害。近年来,利用微生物菌剂治理难降解有机污染物的研究已取得较好的进展。综述微生物菌剂在国内外的发展历程,介绍微生物菌剂制备中常用的固定化技术及载体材料,并分析总结微生物菌剂在酚类物质、多环芳烃和多氯联苯等有机污染物治理中的研究进展。在此基础上,提出治理难降解有机污染物的微生物菌剂研发所存在的主要问题及其展望。     

植物-微生物联合对环境有机污染物降解的研究进展

环境中有机污染物的过量积累对生态系统及人类健康造成严重威胁。近年来,许多学者研究发现植物-微生物联合作用对环境中有机污染物的去除及生态系统的修复具有非常显著的效果。本文主要从植物-内生菌、植物-菌根菌以及植物-根际微生物这三个层面详细阐述植物-微生物联合降解有机污染物的研究现状,分析植物-微生物在联合降解中的作用,揭示植物-微生物联合降解的机理。但就目前而言,植物-微生物联合降解有机污染物仍存在许多问题,植物-微生物联合降解有机污染物的机理及生态学效应仍不清楚。因此,还需要进一步探讨其潜在作用机制并加强应用实践,这将有助于污染生态系统的治理,促进环境可持续发展。     

丛毛单胞菌在环境污染物降解方面的研究进展

环境污染物的微生物降解是环保领域研究的一个热点。研究发现,丛毛单胞菌对多种污染物有很好的降解效果。综述目前已分离的一些丛毛单胞菌对不同污染物的降解特性、代谢途径,并分析了影响其降解效果的各种因素,介绍应用现状并对前景进行展望。     

两相系统在疏水性有机污染物高效降解菌富集培养中的应用研究进展

环境中疏水性有机污染物(Hydrophobic organic pollutants,HOPs)的浓度日益增加,获取HOPs高效降解功能微生物能有效提高HOPs污染治理效率。近年来,利用两相系统促进HOPs微生物降解转化的研究已取得一定进展。本文重点从两相系统的结构特点及其富集HOPs降解功能微生物的原理、主要影响因素和应用情况等方面进行综述,并在此基础上对两相系统在毒害性HOPs微生物加速降解脱毒中所存在的主要问题及其应用前景进行讨论和展望。     

微生物治理有机污染物

这些年来,微生物科学工作对利用微生物治理环境中有害、有毒有机污染物的研究取得重要进展。利用微生物对各类不同的有机污染物进行降解和转化有着巨大潜力,这同微生物所具备的几方面的特点密切相关：(1)个体微小,比表面积大．代谢速度快;(2)种类繁多(含未培养的微生物),分布广(含地球以外的生命体),代谢类型多样;(3)繁殖快、易变异、适应性强(含各类嗜极微生物);     

真菌异化硝酸盐还原机理的研究进展

真菌异化硝酸盐还原途径的发现打破了反硝化仅存在于原核细胞这一传统观念。真菌异化硝酸盐还原途径是在环境中氧供给受限的情况下发生的, 包括反硝化和氨的发酵。硝酸盐能诱导产生反硝化作用的酶, 其中, 硝酸盐还原酶与亚硝酸还原酶位于线粒体中, 它们所催化的酶促反应能偶联呼吸链ATP合成酶合成ATP, 同时产生NO。与参与反硝化作用前两个酶不同, 真菌NO还原酶能以NADH为直接电子供体将NO还原为N2O, 在NAD+的再生和自由基NO的脱毒中起着重要作用。氨发酵则将硝酸盐还原成NH4+, 同时偶联乙酸的生成和底物水平磷酸化。此文从参与该过程的关键酶、关键酶的表达调节、真菌与细菌异化硝酸盐还原的比较等角度综述了真菌异化硝酸盐还原的最新研究进展。     

微生物对环境中难降解有机污染物共代谢作用

对微生物共代谢途径的概念、机理、类型进行了综述,详细介绍了微生物共代谢作用在去除难降解有机污染物过程中所起到的重要作用,并对微生物共代谢作用降解有机污染物的关键因素及其应用价值做出分析。     

Spatial sequencing of microbial reduction of chromate and nitrate in membrane bioreactor

Sequential reduction of chromate and nitrate, two competitive electron acceptors, has been demonstrated for strains of Pseudomonas genus for both planktonic cells and cells immobilised in agar layers on the surface of synthetic membrane. Denitrification occurs practically after chromate depletion. This order of reduction process is consistent with redox potentials of the respective reactions. In a membrane bioreactor, competitive inhibition results in nitrate transfer through the membrane without transformation. Thus the receiving phase is contaminated with nitrate. To address this problem, a membrane has been used for spatial sequencing of chromate and nitrate reduction. Bacterial cells were immobilised in two layers with each layer placed on opposing sides of the membrane. By this means, chromate reduction is localised into the layer contacting the feed phase while nitrate reduction occurs in the layer facing the receiving phase. As a result, only traces of the pollutants are detected in the receiving phase.     

有机物及重金属植物修复研究进展

植物修复技术是近年来发展起来的一种非常有前途的生物治理技术 ,也是当前学术界研究的热点领域 .本文对植物修复的类型 ,植物修复土壤、水体有机污染物、重金属和某些放射性核素的过程、机理及可能影响因子作了概括和详尽讨论 ,并就国内外近年来植物修复技术在污染环境中的应用和研究成果进行了综述     

Microbes involved in dissimilatory nitrate reduction in the human large intestine

Nitrate-limited batch cultures, incorporating 20 different fermentation substrates and inoculated with human faeces, mainly selected for the growth of enterobacteria. The microbial diversity involved was determined by a combination of phenotypic and genotypic procedures. Continuous culture with lactate as the sole electron donor selected for similar micro-organisms, but when antibiotics were incorporated to inhibit Escherichia coli and lactate was replaced with choline, there was a wider microbial diversity recovered. Clostridium ramosum and Bacteroides vulgatus were then isolated as well as enterobacteriaceae.     

Dissimilatory nitrate and dimethylsulphoxide reduction in Rhodopseudomonas capsulata

Abstract The electron flow to the dissimilatory nitrate reductase (NRII), and dimethylsulphoxide (DMSO) oxidoreductase in Rhodopseudomonas capsulata strains was studied. Our results support the view that DMSO reduction, like dissimilatory nitrate reduction was linked to the electron transfer chain and probably coupled to energy conservation.     

Cells of Pseudomonas putida and Enterobacter sp. adapt to toxic organic compounds by increasing their size

The phenol-degrading solvent-tolerant bacterium Pseudomonas putida P8 changed its cell shape when grown in the presence of aromatic compounds such as phenol and 4-chlorophenol. The sizes of cells that had been growing after addition of different concentrations of the toxic compounds were measured using a coulter counter that calculates the sizes of the rod-shaped bacteria to diameters of virtual spheres. The cells showed an increase in the diameter depending on the toxic effects of the applied concentrations of both solvents. The same effect was measured for an alkanol degrading bacterium, Enterobacter sp. VKGH12, in the presence of n-butanol. The reaction of the cells to different concentrations of n-butanol was examined by scanning electron microscopy. With this technique it could be shown that the size of the bacteria increased with increasing concentrations of n-butanol. These changes in cell size were dependent on the cellular activity and occurred only after addition of non-lethal concentrations. In the presence of lethal concentrations that completely inhibited cell growth, the cell sizes were similar to those of cells without intoxication. Taking into account the mathematical formula for spherical and cylindrical diameter and surface, respectively, the cells reacted to the presence of organic solvents by decreasing the ratio between surface and volume of the cells and therefore reducing their relative surfaces. As the cell surface and especially the cytoplasmic membrane are the major targets for the toxic effects of membrane-active compounds, this reduction of the relative surface represents an adaptive response to the presence of such compounds.     

Effect of temperature and benzalkonium chloride on nitrate reduction

The effect of temperature and benzalkonium chloride (BAC) on nitrate reduction was investigated in batch assays using a mixed nitrate reducing culture. Nitrate was transformed completely, mainly through denitrification, to dinitrogen at 5, 10, 15 and 22 °C. In the absence of BAC, reduction of individual nitrogen oxides had different susceptibility to temperature and transient nitrite accumulation was observed at low temperatures. When the effect of BAC was tested up to 100 mg/L from 5 to 22 °C, denitrification was inhibited at and above 50 mg BAC/L with transient nitrite accumulation at all temperatures. The effect of BAC was described by a competitive inhibition model. Nitrite reduction was the denitrification step most susceptible to BAC, especially at low temperatures. BAC was not degraded during the batch incubation and was mostly biomass-adsorbed. Overall, this study shows that low temperatures exacerbate the BAC inhibitory effect, which in turn is controlled by adsorption to biomass.     

Sorption of hydrophobic organic contaminants and trace metals on phytoplankton and implications for toxicity assessment

The partitioning of trace metals and hydrophobic organic contaminants to phytoplankton determines their toxicity as well as their fate and transport in aquatic ecosystems. Accurate impact assessments, therefore, depend on a good understanding of the factors regulating the sorption of these compounds to biotic particles. The accumulation of chlorinated organic compounds in phytoplankton is generally considered as being due solely to physical sorption, described by reversible equilibrium models based on Langmuir or Freundlich isotherms. On the other hand, the uptake of trace metals is a two phase process: a fast sorption component viewed as an ionexchange or a covalent bonding process with cell surface ligands, followed by an intracellular transport phase that is dependent on cellular metabolic activity. The uptake of inorganic and hydrophobic organic pollutants and their bioaccumulation are influenced in a complex manner by duration of exposure and cell density, by environmental factors such as pH, the concentration of cations and of dissolved and colloidal organic matter, as well as by phytoplankton physiological condition. High concentrations of H⁺, Ca²⁺, and Mg²⁺ ions will reduce trace metal sorption by directly competing for uptake sites on the cell's surface, whereas the presence of dissolved organic carbon such as natural and synthetic chelators and phytoplankton exudates will reduce the bioavailability of both trace metals and hydrophobic organic contaminants. Thus, the impact of toxic contaminants on phytoplankton may be determined as much by the factors influencing uptake and partitioning as by the potency of the toxicants and interspecies differences in sensitivity. Recommendations for improving toxicity assessments are presented.     

有机污染环境的植物修复研究进展

分析了近年来国内外的文献资料,对有机污染物污染环境的植物修复研究进展作了综述。植物能通过根系从环境中吸收和积累PCBs、PAHs等有机污染物,并将吸收的TNT、TCE及有机农药降解为高极性产物、水和CO2;另一方面植物根际可促进有机污染物的根际生物吸收与,使植物对有机污染环境的修复效果更明显。文中探讨了有机污染环境的植物修复技术的优势、问题与未来的研究。