水体沉积物中微生物厌氧呼吸耦合多环芳烃降解的研究进展

多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)是一种具有致癌、致畸、致突变的持久性有机污染物。本文在分析国内外主要水体沉积物中PAHs污染状况的基础上,综述了近几年有关厌氧水体沉积物中微生物以硝酸盐、Fe(III)以及硫酸盐为电子受体进行呼吸耦合PAHs降解的研究概况。此外,还总结了基于微生物的PAHs降解基因组、蛋白质组、代谢组以及菌群水平上互作网络的研究进展,以期为进一步加速PAHs污染水体沉积物原位生物修复提供科学理论参考。     

关于微生物修复有机污染土壤的探究

微生物修复是一种利用自然或人工方式培育微生物群落,通过提高其代谢能力来去除毒性污染物或将其转化为无毒物质的一种生物修复技术。有机土壤污染是较为普遍的一种土壤污染,因此应选用恰当的微生物修复方法对其进行修复。故开展微生物修复有机污染土壤的研究很有必要。     

水体及沉积物中微生物的分离、检测与鉴定

微生物在海洋环境中起着非常重要作用,对其的研究技术也在不断地发展。作综述了海洋水体及沉积物环境中微生物的分离、检测与鉴定等方面的技术方法,并评价它们在微生物工作中的有效性及效率,指出各方法的优点和不足。     

土壤与水体有机污染的生物修复及其应用研究进展

系统论述了土壤、水有机污染物的主要来源、特点、有机污染生物修复的概念、应用范围、成功实例与研究进展等,特别是对于泄漏石油污染的生物成功降解方法、效果,土壤中易爆炸物如ＴＮＴ、废水中有机污染的有效降解等,评价了生物修复所具有突出优势,对有机、无机污染物降解过程中植物、微生物筛选、基因修饰、分子克隆与转基因植物方面近年来所取得的惊人成果与突破性进展,无疑正激励着人们开拓更大的应用范围。预计不久的将来,更多具有环境净化与生物修复功能的商业性综合技术与高效性工程生物将投入应用。     

工业有机污染对小型水体沉积物真菌群落的影响分析

【背景】有机污染对水体沉积物中的微生物多样性影响极大,而目前有关污染水体沉积物中真菌多样性的研究较少。【目的】研究不同程度有机污染下水体沉积物中真菌种群的多样性特征,探究工业有机污染对真菌群落的影响。【方法】应用化学分析方法和高通量测序技术进行研究,并分析水质、沉积物成分等环境因子与沉积物真菌多样性的相关性。【结果】随着污染程度的降低,水体沉积物中真菌序列数、OTU数和Shannon多样性指数均呈上升趋势。未分类真菌、子囊菌门和担子菌门是沉积物真菌群落中的主要优势种类,主要优势属为Zopfiella、Westerdykella、Clypeosphaeria、Ilyonectria、Paracremonium、Aspergillus。真菌Shannon指数与水体溶解氧(dissolvedoxygen,DO)极显著正相关,与沉积物有机质和总磷含量显著负相关,Simpson指数与水体总氮(total nitrogen,TN)、氨氮(NH3-N)、总磷(total phosphorus,TP)显著相关。【结论】有机污染导致水体溶解氧下降和沉积物有机质增加,从而导致污染区真菌多样性显著下降。Zopfiella、Penicillium、Emericellopsis、Westerdykella、Jugulospora、Chromelosporium可能参与曝气处理区域沉积物兼氧条件下污染物的去除,Ilyonectria、Mortierella、Epicoccum可能主要参与水生生物残体分解、污染物的吸附沉降等过程。     

产电微生物Shewanella菌厌氧呼吸代谢网络研究进展

以模式菌株Shewanella oneidensis MR-1为代表的Shewanella菌属产电微生物广泛分布于自然水体环境中。作为兼性厌氧菌,Shewanella菌除了能进行有氧呼吸外,还能利用多种电子受体进行厌氧呼吸。通过多种细胞色素所组成的复杂电子传递网络,Shewanella菌不仅能利用渗入到周质空间的可溶性电子受体进行厌氧呼吸,更为特殊的是其能够借助电子的跨膜传递实现对胞外不溶性电子受体的异化还原代谢。本文概述了近年来Shewanella菌厌氧代谢途径的研究进展,探讨电子传递网络对Shewanella菌呼吸多样性及环境适应性的影响。     

金属还原菌希瓦氏菌厌氧呼吸能力及其在环境修复中的研究进展

Shewanella oneidensis MR-1是一种模式金属还原菌,它能够在厌氧条件下,将多种金属化合物和人工合成染料等作为电子受体还原代谢。因此,该菌常常被用于生态修复等研究。厌氧条件下,S.oneidensis MR-1能够将细胞质内或细胞内膜产生的电子通过定位于细胞内膜、细胞膜周质和细胞外膜上的c-血红色素蛋白或还原酶所组成的具有多样性的电子传递系统,最终传递到存在于细菌细胞外环境中的电子受体。通过对多种电子传递过程的介绍,进一步阐明其对污染物修复和纳米材料合成的机理,从而为未来对该类微生物的利用和开发提供更为充分的理论依据。     

微生物固定化技术在水体修复中的研究进展

微生物固定化技术目前已被广泛应用于环境生态修复等领域,对此,文章围绕微生物固定化技术,基于前人的研究成果和目前微生物固定化技术的相关研究进展,及其在水体修复方面的应用展开了探讨,并提出了发展展望,期望能够为微生物固定化技术的发展应用提供有益参考。     

纳米材料在污染水体和土壤修复中的应用

纳米材料由于其特有的理化性质,如强的吸附性能、高的催化效率,不仅克服了传统污染水体和污染土壤修复技术的不足,而且表现出更高的修复效率。因此,利用纳米材料对污染环境进行修复已成为当今环境领域的研究热点。本文对纳米Fe0、表面修饰的纳米材料、纳米螯合剂等纳米材料近几年在污染水体和污染土壤修复中的进展进行了归纳和总结,并且对其在环境科学与工程领域应用的研究重点进行了展望。     

静止或缓流污染地表水微生物固定化修复技术研究进展

污染地表水体修复问题是最近几年才被广泛关注的环境保护课题,由于污染地表水体的特殊性,常规修复方法难以发挥高效作用,固定化微生物可以通过提供特殊的微环境,较好地保护优势菌不受土著菌恶性竞争,在保持高效修复能力的同时,可以将优势菌屏蔽于恶劣环境之外,在一定程度上克服了传统修复工艺的不足,具有较好的应用前景.本文概述了微生物固定化技术的特点,分析了利用固定化微生物修复污染环境介质存在的问题和可行性,针对城市静止或缓流污染地表水的特征,指出了将微生物固定化技术移植到污染地表水体修复领域需要解决的的关键技术.     

酶法合成功能性低聚糖

功能性低聚糖具有无毒、无残留、稳定性强等特点,作为新型绿色添加剂被广泛应用在食品、饲料、医药行业。国际市场上10余种低聚糖产品中除大豆低聚糖、棉籽糖外,主要采用酶法制备。用于合成功能性低聚糖的酶包括糖苷酶、糖基转移酶和磷酸化酶。本文综述了功能性低聚糖种类、性质和制备方法,分析了酶法合成低聚糖的优缺点,阐述了磷酸化酶种类、催化特性和低聚糖产物。多酶法合成策略和目标酶的分子改造将是酶法合成功能性低聚糖的发展方向。     

Bacterial anaerobic respiration and electron transfer relevant to the biotransformation of pollutants

Bacterial anaerobic respiration is one of the most ancient and essential metabolism processes, possessing the characteristics of both flexibility and high diversity, and a very close relationship with the physiological function in the ecological environment. Under anaerobic conditions, bacteria and anthropogenic substances can form coupling process facilitating terminal electron transfer. Several forms of bacterial anaerobic respiration and electron transfer related to the biotransformation of pollutants, including respiration with humics, sulfonates, halogenated chemicals, azo compounds, TNTs, metallic and non-metallic elements, are reviewed in this paper. These respirations and electron transfers on diverse electron acceptors in the environment have important biotechnological implications because these biochemical reactions have their roles on the transformation/degradation of toxic substances and the cycling of organic carbon as well as many inorganic elements. Furthermore, remediation of sites contaminated with toxic pollutants based on bacterial anaerobic respirations is being recognized widely.     

Microbial diversity and community respiration in freshwater sediments influenced by artificial light at night

An increasing proportion of the Earth''s surface is illuminated at night. In aquatic ecosystems, artificial light at night (ALAN) may influence microbial communities living in the sediments. These communities are highly diverse and play an important role in the global carbon cycle. We combined field and laboratory experiments using sediments from an agricultural drainage system to examine how ALAN affects communities and alters carbon mineralization. Two identical light infrastructures were installed parallel to a drainage ditch before the start of the experiment. DNA metabarcoding indicated that both sediment communities were similar. After one was lit for five months (July–December 2012) we observed an increase in photoautotroph abundance (diatoms, Cyanobacteria) in ALAN-exposed sediments. In laboratory incubations mimicking summer and winter (six weeks each), communities in sediments that were exposed to ALAN for 1 year (July 2012–June 2013) showed less overall seasonal change compared with ALAN-naive sediments. Nocturnal community respiration was reduced in ALAN-exposed sediments. In long-term exposed summer-sediments, we observed a shift from negative to positive net ecosystem production. Our results indicate ALAN may alter sediment microbial communities over time, with implications for ecosystem-level functions. It may thus have the potential to transform inland waters to nocturnal carbon sinks.     

持久性有机污染物在水生食物网中的传递行为

食物网是持久性有机污染物(POPs)在水生生态系统中传递的重要途径,了解其传递行为与机制是POPs生态暴露风险评价的科学基础。从4个方面展开了讨论和分析:(1)食物网主要特征(营养级和食物链长度)与POPs环境行为的关系;(2)POPs在底栖及底栖-浮游耦合食物网中的环境行为;(3)微食物网对POPs环境行为的作用;(4)食物网的变化对POPs环境行为的影响。主要结论如下:(1)已有研究对水生生物中POPs生物放大作用存在较大争议。一般营养级越高,POPs生物富集性越强,但由于各种生态和生理性质的影响,也存在例外情况。食物链长度与POPs生物富集性呈正相关。(2)POPs通过底栖食物网将沉积物中的POPs向上传递,底栖-浮游食物网的耦合提高了高营养级消费者的暴露风险,目前就POPs在底栖食物网中的生物放大性是否大于浮游食物网存在争议。(3)微生物具有较大的比表面积,是吸附POPs的重要载体。另,沉积物中的微生物通过分解有机质,将POPs释放到水柱中。微生物降解也是环境中POPs脱离环境的重要途径。(4)在内、外压力下,食物网结构和功能发生变化,使物质和能量的传递方向和效率发生改变,并与环境理化性质的变化互相耦合,影响POPs的环境行为。当前研究的重点多集中在POPs在浮游食物网,尤其是高营养级浮游食物网中的环境行为,对POPs在底栖及底栖-浮游耦合食物网和微食物网中环境行为的研究相对缺乏。有关POPs在食物网中环境行为的研究多集中在食物网的某个部分,时间尺度较短,缺乏对POPs环境行为动态变化的研究,未来需深入开展多尺度和多角度的POPs在食物网中环境行为的动态变化研究。新型POPs的生产和使用量不断增加,但有关其在食物网中环境行为的相关分析还较为匮乏,需加强研究。     

Rates and controls of anaerobic microbial respiration across spatial and temporal gradients in saltmarsh sediments

This study was undertaken to determine the rates and controls ofanaerobic respiration reactions coupled to organic matter mineralization as afunction of space and time along a transect from a bioturbated creekbank to themidmarsh in Georgia saltmarsh sediments. Sulfate reduction rates (SRR) weremeasured at 3 sites during 5 sampling periods throughout the growth season. Thesites differed according to hydrologic regime and the abundance of dominantplants and macrofauna. SRR and pore water / solid phase geochemistry showedevidence of enhanced sediment oxidation at sites exposed to intensebioturbation. Iron(III) reduction rates (FeRR) were directly determined insaltmarsh sediments for the first time, and in agreement with measured SRR,higher rates were observed at the bioturbated, unvegetated creekbank (BUC) andbioturbated, vegetated levee (BVL) sites in comparison to a vegetated mid-marsh(MM) site. An unexpected result was the fact that SRR varied nearly as muchbetween sites (2–3 x) as it did with temperature or season (3–4 x).The BVL site, vegetated by the tall form of Spartinaalterniflora, always exhibited the highest SRR and carbon oxidationrates (> 4000 nmol cm^–3 d^–1) with high activity levels extending deep ( 50 cm)into the sediment, while the MM site, dominated by the short form ofSpartina, always exhibited the lowest SRR which werelocalized to the top 15 cm of sediment. SRR and FeRR at BUC wereintermediate between those measured at the BVL and MM. Acetate was the mostabundant microbial fermentation product (concentrations up to > 1mM) in marsh porewaters, and its distribution reflectedrespirationactivity. Chemical exchange, caused by bioturbation, appeared to be the primarycontrol explaining trends in rates of sulfate and Fe(III) reduction withmacrophytes and carbon source acting as secondary controls.     

有机污染土壤电动修复过程中微生物的分布特征及模型构建

外加电场下土壤微生物会发生快速繁殖和定向迁移.本研究在十四烷污染土壤中不同位置投加十四烷高效降解菌,并施加1 V·cm^-1的单向直流电场,考察目标菌群的迁移分布及降解特征.结果表明:微生物受电渗析和电泳作用分别向阴极和阳极迁移,电渗析迁移量是电泳的3.5倍.同时,施加电场还会使土壤环境在空间上存在差异进而影响微生物生长,施加电场的土壤中微生物数量平均值为1.16×10⁸ CFU·g^-1 (6 d),是不施加电场处理组的2.3倍;S₂～S₄区是微生物的高效生长区域,电动30 d后,区域平均数量是阴阳极的2.8～3.5倍,是对照处理组的2.1倍.十四烷降解率与微生物数量呈显著正相关关系(r=0.895, P<0.05),最佳降解区域在近阴极区(S₄),可达94.6%.基于试验结果模拟,建立了环境因子修正的电动区域微生物分布模型.该模型结合电动激活和电动运移作用对土壤微生物的叠加影响,实现了定点投加微生物在电动过程中数量的分布模拟.研究结果可为外源功能菌在电动-微生物修复有机污染土壤中的高效引入提供理论依据.     

上覆水性质对沉积物吸附有机污染物能力的影响

采用正交实验法研究了温度、pH、离子强度和溶解性有机质(DOC)对沉积物吸附菲和五氯酚(PCP)能力的影响.结果表明,上覆水温度和pH对个别沉积物的吸附能力有显著影响,其他因素及交互作用对菲和PCP的吸附无显著影响.沉积物对菲的吸附能力随温度升高而降低,对PCP在中温(20℃)时最小.pH对菲的吸附无显著影响,PCP的吸附量随pH升高而降低.DOC升高微弱地降低了菲和PCP的吸附,离子强度升高使PCP的吸附有微弱升高.沉积物对有机污染物的吸附能力主要由沉积物和有机污染物性质决定,受上覆水性质影响较小.     

The availability of organic matter in dried and undried soil,estimated by an anaerobic respiration technique

Summary A study was made of the availability of the organic matter in gamma irradiated and non-irradiated soil, both dried and undried. It was concluded that the release of available soil organic matter during air-drying was the major contributor to the air-drying effect. It was also concluded that the change in microbial populations, which occurred during air-drying, did not contribute significantly to the air-drying effect. In addition it was observed that gamma irradiation affected the availability of soil organic matter in both dried and undried soil, the effect being most marked in the undried soil. It was considered that the anaerobic denitrifying technique which was used in this investigation had definite advantages over aerobic techniques which have been used to study the activity of micro-organisms in soil.