脱卤单胞菌属在厌氧降解有机氯化物及污染场地修复应用中的研究进展

脱卤单胞菌 Dehalogenimonas 是绿弯菌门 (Chloroflexi) 脱卤球菌纲 (Dehalococcoidia) 的一个属。脱卤单胞菌属目前包含 Dehalogenimonas lykanthroporepellens、Dehalogenimonas alkenigignens 和 Dehalogenimonas formicexedens 这 3 个已正式命名的物种,其成员均为严格厌氧的专性有机卤呼吸细菌,利用氢气和甲酸作为电子供体,以氯代烷烃 (例如 1,2,3-三氯丙烷、1,2-二氯丙烷和 1,2-二氯乙烷) 作为电子受体,通过介导还原性脱氯反应获得能量进行生长。我国污染场地地下水中氯代烷烃等有机氯污染较为突出,脱卤单胞菌的产能方式使其在污染场地原位修复中具有重要的应用价值。新近发现的 WBC-2 菌株和"Candidatus Dehalogenimonas etheniformans" GP 菌株可以脱氯降解某些氯代烯烃,其中 GP 菌株能够将一氯乙烯完全脱氯至乙烯,拓展了有限的一氯乙烯脱氯菌种资源,丰富了脱卤单胞菌的生态学功能。文中围绕脱卤单胞菌属的生理生化特性、生态功能及基因组信息进行综述,旨在为污染场地有机氯污染物的清理及工程实施提供理论指导。     

一种新型微生物卤醇脱卤酶的研究进展

卤醇脱卤酶是细菌降解环境中重要污染物有机卤化物的关键酶之一,具有与其他已知脱卤酶不同的脱卤机制。它是一类通过分子内亲核取代机制催化邻卤醇转化为环氧化物的脱卤酶,可以高效催化有机邻卤醇进行脱卤反应,在治理环境污染方面具有十分重要作用。此外,在催化环氧化物和邻卤醇之间的转化反应中,卤醇脱卤酶具有很高的立体选择性,因而在手性药物合成方面也有广阔的应用前景。我们着重从卤化物生物降解途径、脱卤机制及应用等方面介绍了卤醇脱卤酶的最新研究进展,同时对卤醇脱卤酶改造的新方法进行了阐述与展望。     

微生物卤代烷烃脱卤酶研究进展

卤代烷烃脱卤酶是降解卤代脂肪族化合物的关键酶类,在各种地理环境中的不同微生物中广泛存在,在生物降解和工业生产等方面具有重要的应用价值。目前已经生化鉴定了20个卤代烷烃脱卤酶。近些年来对这些酶的酶学特征、蛋白质结构和系统进化进行了详细的研究。同时,为满足应用实践的需求还对卤代烷烃脱卤酶进行了蛋白质工程改造研究。本文将对卤代烷烃脱卤酶研究的一些新的进展进行综述。     

一株脱卤单胞菌属有机卤呼吸细菌的分离纯化与基础特征

[目的]分离鉴定新型有机卤呼吸细菌,拓展有机氯污染物降解菌种资源.[方法]在限制性培养基中,基于特定脱卤微生物的能量代谢特点以及对抗生素的抗性特征,应用绝迹稀释法从脱氯富集培养物中分离纯化新型有机卤呼吸细菌.通过添加酵母提取物和聚合酶链反应-限制性片段长度多态性等方法鉴定菌株纯度.通过考察细胞形态、16SrRNA系统发...     

环境因子对细菌形成芽孢的影响

环境因子对细菌形成芽孢的影响范玉贞（河北省衡水师范专科学校生物学系００３３００）由于芽抱对不良环境和物理、化学杀菌因于有极强的抵抗力，故一般认为芽抱是细菌在不良条件下形成的适应逆境的产物。但实际情况并非完全如此。细菌形成芽抱的根本原因在于细胞内部含有...     

有机卤呼吸微生物菌群营养交互的作用机制

有机卤呼吸细菌(organohalide-respiringbacteria,OHRB)是污染场地土壤与地下水中厌氧降解及生物修复有机卤代污染物的主力军。微生物种群间的资源竞争、生长抑制、代谢交叉喂养(crossfeeding,即营养的动态交换,包括碳源、氮源、氨基酸、维生素、核苷酸、电子供体、电子受体和其他生长因子等)、水平基因转移及其他交互作用机制是群落结构稳定平衡的基础,有利于促进有机卤代污染物消减效率的最大化。本文围绕OHRB种群及与其他微生物种群间的互作机制(如交叉喂养机制、竞争机制及抑制机制等)进行了概述,并对未来互作机制的研究进行了探讨与展望,旨在为有机卤代物污染场地生物修复效率的提高提供科学理论和技术参考依据。     

环境因子和生物因子对黄河三角洲滨海湿地土壤呼吸的影响

采用Li-8150多通道土壤呼吸自动测量系统对黄河三角洲滨海湿地土壤呼吸进行全年连续测定,同步测量了温度、土壤含水量、地上生物量以及叶面积指数等环境因子和生物因子.结果表明: 土壤呼吸日动态在全年尺度上多呈单峰型,但在受到土壤封冻和地表积水干扰时,土壤呼吸日动态呈多峰型.土壤呼吸具有明显的季节动态特征,总体呈单峰型,年平均土壤呼吸速率为0.85 μmol CO₂·m^-2·s^-1,生长季平均土壤呼吸速率为1.22 μmol CO₂·m^-2·s^-1.在全年尺度上,土壤温度是滨海湿地土壤呼吸的主要控制因子,可解释全年土壤呼吸87.5%的变化.在生长季尺度上,土壤含水量和叶面积指数对土壤呼吸的协同影响达到85%.     

基于宏基因组学的卤醇脱卤酶筛选

环境中的多数有机卤化物具有高毒性和低可降解性,卤醇脱卤酶可以催化邻卤醇进行分子内亲和取代生成相应的环氧化物,在消除有机卤化物的污染方面具有十分重要的作用.此外,在催化环氧化物和邻卤醇之间的转化反应中卤醇脱卤酶具有很高的立体选择性,因而在手性药物合成方面也有广阔的应用前景.宏基因组是生境中全部微小生物遗传物质的总和,极大地扩展了微生物资源的利用空间.本文介绍了卤醇脱卤酶的特性及利用宏基因组方法筛选新的卤醇脱卤酶的两种方法及各自的优缺点.     

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。     

地下水脱卤过程中的微生物种间代谢互作：提高原位氯代烯烃厌氧脱氯效能的有效途径

有机卤呼吸细菌(organohalide-respiring bacteria, OHRB)在氯代烯烃污染地下水的原位生物修复中扮演着关键性的角色,提高其丰度及活性对氯代烯烃的完全去除具有重要意义。在实际环境中,有机卤呼吸细菌往往与多种微生物共存,微生物种间代谢互作现象十分普遍,有机污染物的完全无害化往往需要通过微生物菌群的协同代谢作用来实现。因此,本文围绕微生物种间代谢互作进行综述,对目前获得的脱氯微生物菌种资源及脱氯机理进行了回顾,重点阐述了专性OHRB、非专性OHRB和非OHRB的种间代谢互作行为及机制,并提出以种间代谢互作为指导进行合成微生物群落的构建来有效提高氯代烯烃厌氧生物降解效率,为实现环境氯代烯烃类有机污染物的快速、彻底无害化提供理论指导。     

Benzoate-driven dehalogenation of chlorinated ethenes in microbial cultures from a contaminated aquifer

Microbial dehalogenation of tetrachloroethene (PCE) and cis-dichloroethene (cis-DCE) was studied in cultures from a continuous stirred tank reactor initially inoculated with aquifer material from a PCE-contaminated site. Cultures amended with hydrogen and acetate readily dechlorinated PCE and cis-DCE; however, this transformation was incomplete and resulted in the accumulation of chlorinated intermediates and only small amounts of ethene within 60 days of incubation. Conversely, microbial PCE and cis-DCE dechlorination in cultures with benzoate and acetate resulted in the complete transformation to ethene within 30 days. Community fingerprinting by denaturing gradient gel electrophoresis (DGGE) revealed the predominance of phylotypes closely affiliated with Desulfitobacterium, Dehalococcoides, and Syntrophus species. The Dehalococcoides culture VZ, obtained from small whitish colonies in cis-DCE dechlorinating agarose cultures, revealed an irregular cell diameter between 200 and 500 nm, and a spherical or biconcave disk-shaped morphology. These organisms were identified as responsible for the dechlorination of cis-DCE to ethene in the PCE-dechlorinating consortia, operating together with the Desulfitobacterium as PCE-to-cis-DCE dehalogenating bacterium and with a Syntrophus species as potential hydrogen-producing partner in cultures with benzoate. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

配糟对清香型白酒发酵中环境因子及微生物群落的影响

【背景】环境因子是影响微生物生长代谢的重要因素,解析半开放条件下酿造过程中环境因子对微生物群落演替的作用对于清香型白酒生产调控具有重要意义。配糟在白酒发酵过程中起着调节发酵速度的作用,其对微生物群落组成变化的影响尚不明确。【目的】揭示使用不同发酵周期配糟对清香型白酒发酵过程中环境因子及微生物群落演替的影响。【方法】采用PacBio测序平台和多元统计分析比较使用2种配糟酒醅中微生物群落结构组成,结合蒙特卡洛置换检验明确环境因子对微生物群落的影响。【结果】与使用正常发酵周期配糟酒醅相比,使用延长发酵周期配糟酒醅水分较低,而酸度、氨基酸态氮、总游离氨基酸、还原糖和残余淀粉较高;微生物多样性和丰富度分析发现,使用延长发酵周期配糟酒醅中细菌α多样性极显著高于使用正常发酵周期配糟酒醅(P<0.001),而真菌α多样性显著/极显著低于使用正常发酵周期配糟酒醅(P<0.05, P<0.001);通过组间差异性分析发现,细菌群落共产生28个差异指示种,而真菌群落共产生15个差异指示种;水分、酸度、氨基酸态氮、还原糖、残余淀粉和总游离氨基酸对微生物群落结构的影响显著(P<0.05)...     

Quality and environmental factors affecting Trichogramma brassicae efficiency under field conditions

Field parasitism of the egg parasitoid Trichogramma brassicae Bezdenko (Hymenoptera, Trichogrammatidae) (synonymous to T. maidis Pint. et Voegele) on Ostrinia nubilalis Hübner was compared to four single quality parameters (walking speed, fecundity on the factitious host Ephestia keuhniella Zeller, fecundity on the natural host O. nubilalis, and life span) previously measured in the laboratory and, a quality index calculated from three of the measured parameters. A single quality parameter (fecundity on E. keuhniella) and the calculated quality index showed a correlation to T. brassicae field parasitism, for different T. brassicae populations. The number of female Trichogramma released clearly influenced parasitism but not in the same proportion for all populations tested, reflecting that numbers released can only to some extent compensate for low quality in Trichogramma. Variation indegree hours above 18°C also influenced field parasitism. When incorporating degree hours to the quality index a significant correlation R²=0.56 (P=0.01) is obtained. In this work fecundity of T. brassicae on E. keuhniella can be as good an indicator for the potential field performance of T. brassicae, as the quality index which takes into account three quality parameters. Since environmental factors can obscure the potential performance of a population, i.e., one which under optimal laboratory conditions performs well, the quality index gives only a partial indication of how the released strains will perform in the field.     

不同环境因子及破壳处理对锥栗种子萌发特性的影响

锥栗(Castanea henryi)是我国南方重要的木本粮食树种和特色果树资源,具有很高的食用及药用价值。为探明最适宜锥栗种子萌发的条件,该研究以当年采收的锥栗种子为材料,探讨了温度、光照、基质、基质含水量以及破壳处理等对锥栗种子萌发的影响,为锥栗种苗繁育提供理论基础。结果表明:(1)锥栗种子萌发的最适温度是25℃,其最终萌发率为92.67%,在其他温度条件下,锥栗种子的萌发率有所下降,但与25℃条件下的萌发率无显著差异。(2)黑暗条件可缩短锥栗种子发芽时间,明显提高种子的萌发率和发芽势,但黑暗条件下的种子胚根长度显著小于周期性光照条件下的胚根长度。(3)锥栗种子在泥炭土中的萌发率和发芽势均高于在河沙中的萌发率和发芽势,且泥炭土中种子胚根长度显著长于河沙中的种子胚根长度。(4)基质含水量对锥栗种子萌发率和发芽势无显著性影响。(5)种皮的机械阻碍是限制锥栗种子萌发的因素之一,破壳处理后,锥栗种子的发芽势和胚根长度与未破壳相比差异显著,实际生产中剪破种壳能加快种子的萌发进程。     

环境因子对东海原甲藻生长及脲酶活性的影响

以我国东南沿海大规模赤潮原因种东海原甲藻为实验材料,研究了环境因子对其生长及脲酶活性的调控作用。结果表明,东海原甲藻的适宜生长温度为20—25℃,而25℃下脲酶活性最高。在光强2μmol m-2s-1条件下细胞密度显著下降(P0.05),但仍能维持较高的脲酶活性(9.405 fmol h-1个-1)。在盐度20—40范围内,东海原甲藻能够维持快速生长和较高的脲酶活性。氮源组成对东海原甲藻生长无显著影响,但对脲酶活性影响较大。具体而言,东海原甲藻脲酶活性与尿素浓度呈显著正相关关系,而无机氮源NH+4和NO-3对其脲酶活性具有显著的抑制作用,在氮缺乏条件下脲酶活性明显增强。东海原甲藻脲酶活性对环境温度、光照、盐度和营养的响应特征可能是在长期进化中形成的生态适应策略,使其在无机氮源不足时得以转而利用有机氮源,从而在资源竞争中占据有利地位。     

Molecular characterization of microbial populations at two sites with differing reductive dechlorination abilities

This study compares three molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP), RFLP analysis with clone sequencing, and quantitative PCR (Q-PCR) for surveying differences in microbial communities at two contaminated field sites that exhibit dissimilar chlorinated solvent degradation activities. At the Idaho National Engineering and Environmental Laboratory (INEEL), trichloroethene (TCE) was completely converted to ethene during biostimulation with lactate. At Seal Beach, California, perchloroethene (PCE) was degraded only to cis-dichloroethene (cDCE) during biostimulation but was degraded to ethene after bioaugmentation with a dechlorinating culture containing Dehalococcoides strains. T-RFLP analysis showed that microbial community composition differed significantly between the two sites, but was similar within each site among wells that had low or no electron donor exposure. Analysis of INEEL clone libraries by RFLP with clone sequencing revealed a complex microbial population but did not identify any Dehalococcoides strains. Q-PCR targeting the 16S rRNA gene of Dehalococcoides strains – known for their unique capability to dechlorinate solvents completely to ethene – revealed a significant population at INEEL, but no detectable population at Seal Beach prior to bioaugmentation. Detection of Dehalococcoides by Q-PCR correlated with observed dechlorination activity and ethene production at both sites. Q-PCR showed that Dehalococcoides was present in even the pristine well at INEEL, suggesting that the difference in dechlorination ability at the two sites was due to the initial absence of this genus at Seal Beach. Of the techniques tested, Q-PCR quantification of specific dechlorinating species provided the most effective and direct prediction of community dechlorinating potential.     

Role of sulfate in microbial transformations of environmental contaminants: Chlorinated aromatic compounds

Despite recent progress made in describing microbial transformations that occur under anaerobic conditions, our understanding of the role sulfate‐reducing bacteria may play in the remediation of environmental contaminants is still very limited. The objective of this mini‐review is to summarize what is currently known of the metabolism of chlorinated aromatic compounds in the presence of sulfate. Sulfidogenic processes are discussed with respect to the thermodynamics of haloaromatic oxidation and to their potential use in the in situ bioremediation of hazardous organic wastes. A comprehensive listing is made of anaerobic transformations that involve both halogenated and nonhalogenated monoaromatic substrates by denitrifiers, dissimilatory iron‐reducing bacteria, and methanogenic consortia. In contrast to other anaerobic processes, studies involving sulfate‐mediated metabolism of hazardous organic compounds have been neglected; however, the recent success in defining methanogenic transformations, in particular, has enhanced expectations of defining an analogous role for sulfate‐reducing microbial communities in low redox environments that have become contaminated with hazardous substances.     

Effects of nitrate treatment on a mixed species, oil field microbial biofilm

Biofilms of bacteria, indigenous to oil field produced water, were grown in square section, glass capillary flow cells at 45 °C. Initially, in situ image analysis microscopy revealed predominantly coccoid bacteria (length-to-width ratio measurements (l _c:w _c) of bacterial cells gave a mean value of 1.1), while chemical measurements confirmed sulphate reduction and sulphide production. After nitrate ion addition at 100 and 80 mg/l, in the two repeat experiments respectively, the dominance of rod-shaped bacteria (mean l _c:w _c = 2.8) was observed. This coincided with the occurrence of nitrate reduction in the treated flow cells. Beneficially, no significant increase in biofilm cover was observed after the addition of nitrate. The dominant culturable nitrate-reducing bacterium was Marinobacter aquaeolei. The l _c:w _c ratio measured here concurs with previously reported cell dimensions for this organism. Several Marinobacter strains were also isolated from different oil fields in the North Sea where nitrate treatment has been applied to successfully treat reservoir souring, implying that this genus may play an important role in nitrate treatment.     

土壤微生物多样性及其环境影响因子研究进展

土壤中存在丰富的微生物资源,不同土壤系统具有不同的微生物群落,微生物多样性既依赖于生态系统又服务于生态系统。本文从物种多样性、遗传多样性、生态类型多样性、功能多样性四个方面对土壤微生物多样性进行了新的诠释,总结论述了土壤微生物多样性与环境因子如土壤、植物群落和气候条件之间的关系,并对目前存在的问题和今后面临的挑战提出几点看法。