发光细菌在水环境生物毒性检测中应用的研究进展

发光细菌是一类自身含发光基因且能够发出可见光的细菌,其分布非常广泛。由于具备了日常毒性检测所要求的快速灵敏以及再现性好的特点,发光细菌法愈来愈受到关注,且因其快速和低成本的特点常被用作早期预警系统。基因操作技术的介入更使得发光细菌试验具有了分辨各种毒性的功能。本文综述了发光细菌在环境毒性检测中的进展,重点介绍了基于发光细菌的毒性试验方法,以及在水质检测中的应用。     

植物内生细菌对植物健康的作用

植物内生菌是一个多样性十分丰富的微生物类群,存在于没有外在感染症状的健康植物组织内,并与宿主植物协同进化.随着研究领域的不断拓宽和研究方法的不断更新,植物内生菌与植物健康的关系以及应用逐渐成为研究热点.本文主要综述了内生细菌的多样性、进入植物组织内的机制以及内生细菌的主要功能及应用,提出了现阶段内生菌研究存在的问题,并展望了内生菌研究的前景.     

植物促生菌提高植物重金属耐受性研究进展

近年来植物修复技术因其独特的优势而被广泛关注。许多植物被认为是有价值的利用资源, 然而, 最有实际使用价值的植物对重金属的耐受性有限, 实际应用中变得越来越困难。植物促生菌资源对环境无污染, 具有独特的多样性和巨大的潜力。随着资源的开发和技术的发展, 微生物调控将会使植物修复技术变得更加可行和更有价值。回顾近年来新兴的微生物调控技术, 主要是植物促生菌的筛选、鉴定和应用价值。     

植物内生细菌的侵染定殖规律研究进展

详细综述了植物内生细菌的侵染定殖过程,即吸附、侵入、定殖三个阶段。着重阐述了对植物内生细菌的定殖检测方法,包括抗生素标记法、免疫学方法、基因标记法及特异性寡核苷酸片段标记法等。另外,对植物内生细菌的来源及定殖影响因子也进行了系统讨论,并对未来植物内生细菌定殖研究前景作了展望。     

A novel method for sampling bacteria on plant root and soil surfaces at the microhabitat scale

This study reports the first method for sampling bacteria at a spatial scale approximating a microhabitat. At the core of this method is the use of tungsten rods with laser-cut tips of known surface area (0.013 mm(2)). Exposed plant root or soil surfaces were viewed with a dissecting microscope and micro-sampling rods were guided to sample sites using a micro-manipulator. Bacteria that adhered to the sampling tips were then recovered for microbiological analyses. The efficiency of this method for removing bacteria from root surfaces was similar to that with which bacteria are recovered from dissected root segments using the conventional technique of washing. However, as the surface area of the micro-sampling tips was known, the new method has the advantage of eliminating inaccuracy in estimates of bacterial densities due to inaccurate estimation of the root or soil surface sampled. When used to investigate spatial distributions of rhizoplane bacteria, the new technique revealed trends that were consistent with those reported with existing methods, while providing access to additional information about community structure at a much smaller spatial scale. The spatial scale of this new method is ca. 1000-times smaller than other sampling methods involving swabbing. This novel technique represents an important methodological step facilitating microbial ecological investigations at a microhabitat scale.     

Microbiology of petroleum reservoirs

Although the importance of bacterial activities in oil reservoirs was recognized a long time ago, our knowledge of the nature and diversity of bacteria growing in these ecosystems is still poor, and their metabolic activities in situ largely ignored. This paper reviews our current knowledge about these bacteria and emphasises the importance of the petrochemical and geochemical characteristics in understanding their presence in such environments.     

细菌的信号转导系统及其在耐药中的作用

耐药菌的日益增多给临床治疗带来巨大的困难,揭示耐药机制成为遏制耐药菌的基本环节.细菌的信号系统是菌体之间信息交流的主要渠道,在调控细菌耐药性方面发挥重要的作用.本文梳理了细菌双组分系统、群体感应系统、第二信使、吲哚等细菌信号系统(分子)与细菌耐药性的关系,总结了各信号系统调控细菌耐药性的机制和途径,包括调控生物膜的形成...     

异养硝化细菌脱氮特性及研究进展

异养硝化细菌能够在利用有机碳源生长的同时将含氮化合物硝化生成羟胺、亚硝酸盐、硝酸盐等产物, 多数还能同时进行好氧反硝化作用, 直接将硝化产物转化为含氮气体。因此, 这类细菌已成为废水处理中生物脱氮新工艺的重要研究对象。本文综述了目前所分离出的一些异养硝化菌的脱氮特性, 分析了各种环境条件如温度、pH、溶解氧、碳源类型、C/N以及抑制剂等对异养硝化菌的影响, 并介绍了异养硝化菌的应用现状及前景。     

综述与专论：细菌的信号转导系统及其在耐药中的作用

耐药菌的日益增多给临床治疗带来巨大的困难,揭示耐药机制成为遏制耐药菌的基本环节。细菌的信号系统是菌体之间信息交流的主要渠道,在调控细菌耐药性方面发挥重要的作用。本文梳理了细菌双组分系统、群体感应系统、第二信使、吲哚等细菌信号系统(分子)与细菌耐药性的关系,总结了各信号系统调控细菌耐药性的机制和途径,包括调控生物膜的形成、调节药物外排泵的活性、激活抗生素灭活酶、提高耐药基因表达水平、促进耐药基因转移、修饰细胞壁结构等,涉及到细菌耐药的多个环节。各信号系统不仅可以独立调控耐药,还可以互相作用,形成调控网络,从多个层面调节细菌耐药性。因此,靶向细菌信号系统,阻断菌体之间的信号联络,有望成为遏制细菌耐药性日益严重的新策略。     

细菌分解代谢转座子研究

近年来 ,随着人工合成化学物质大量进入环境 ,现已在环境中发现了新的适应性的细菌对有机污染物的代谢机制。许多分解代谢基因与插入元件或转座子相连 ,因此 ,分解代谢基因可以在细菌间快速传播。这种快速传播有利于新的降解途径的产生。因此 ,这种代谢全能性可以被开发并在生物修复污染环境中起到关键作用     

Epiphytic microorganisms on strawberry plants (Fragaria ananassa cv. Elsanta): identification of bacterial isolates and analysis of their interaction with leaf surfaces

Epiphytic bacteria were isolated from strawberry plants cultivated in the field or in the greenhouse in order to investigate their interaction with leaf-surface transport properties. Colonization of lower leaf sides was higher on field-grown plants, whereas upper leaf sides were more densely colonized on plants cultivated in the greenhouse. Fungal isolates significantly contributed to total microbial biomass on leaf surfaces of greenhouse-grown strawberry plants, whereas these organisms were rarely abundant on field-grown plants. Microscopic investigations of bacteria in the phyllosphere revealed that the highest densities of bacteria were observed on living trichomes, which obviously provide a source of nutrients. Isolated strains were characterized by colony morphology, microscopy and histochemistry. About 324 isolated bacterial strains were grouped into 38 morphotypes. Of the morphotypes, 12 were identified by 16S rRNA gene sequencing. Dominating bacteria belonged to the genus Pseudomonas, Stenotrophomonas, Bacillus and Arthrobacter. Cuticular water permeability of isolated cuticular membranes and intact leaf disks was measured before and after treatment with one of the most prominent epiphytic bacteria, Pseudomonas rhizosphaerae. Results showed that cuticular transpiration was significantly increased by P. rhizosphaerae. This shows that leaf-surface properties, such as cuticular water permeability, can be influenced by bacteria, leading to improved habitable conditions in the phyllosphere.     

乳酸菌治疗乳糖不耐受症的研究进展

乳糖不耐受与人体健康尤其是婴儿期的营养密切相关,该病症主要影响人体对乳糖的消化吸收。乳酸菌作为有效的微生态制剂,已被广泛应用于医药卫生、营养保健、食品工业等领域。近年研究发现,含乳酸菌的微生态制剂在治疗乳糖不耐受症方面具有明显疗效。本文综述了乳糖不耐受症的发病机制及分型、乳酸菌治疗乳糖不耐受症的研究进展。     

aac（6＇）-Ib-cr介导的喹喏酮类新耐药机制研究进展

AAC（6＇）-Ib是重要的氨基糖苷乙酰基团转移酶,其变异基因aac（6＇）-Ib-cr可同时作用于氨基糖苷类和氟喹诺酮类两类结构不同的抗生素,是引起细菌耐药性的一种重要作用机制。该文主要对aac（6＇）-Ib-cr介导的喹诺酮类新耐药机制相关研究进行综述。     

植物相关细菌中Ⅵ型分泌系统的功能研究进展北大核心

型分泌系统(typeⅥsecretion system,T6SS)是一种强大的细菌分子武器,它通过将效应蛋白注入原核或真核细胞而介导细菌间竞争并影响宿主的生命活动。T6SS广泛分布于革兰氏阴性菌中,主要存在于变形菌门(Proteobacteria)。尽管T6SS的研究大多集中在动物相关细菌上,但它在植物相关细菌中的作用不能被忽视。本文对植物相关细菌的T6SS进行了较为详细的介绍,主要从T6SS的发现、T6SS在植物相关细菌间竞争中的作用、在细菌与植物互作中的作用以及在植物生物防治中的作用等4个方面综述了最新的研究成果,旨在为今后更好地研究植物相关细菌T6SS的生物学功能及其应用提供指导。     

Promotion of Plant Growth by Bacterial ACC Deaminase

To date, there has been only limited commercial use of plant growth-promoting bacteria in agriculture, horticulture, and silviculture. However, with recent progress toward understanding the mechanisms that these organisms utilize to facilitate plant growth, the use of plant growth-promoting bacteria is expected to continue to increase worldwide. One of the key mechanisms employed by plant growth-promoting bacteria to facilitate plant growth is the lowering of plant ethylene levels by the enzyme 1-aminocyclopropane-1-carboxylate (ACC) deaminase. This article reviews the published work on this enzyme, with an emphasis on its biochemistry, protein structure, genes, and regulation. In addition, this article provides some initial insights into the changes in both plants and ACC deaminase-containing plant growth-promoting bacteria as a consequence of plant-microbe interactions. Finally, a brief discussion of how bacterial ACC deaminase and indoleacetic acid (IAA) together modulate plant growth and development is included.     

Allelopathic Bacteria and Their Impact on Higher Plants

The impact of allelopathic, nonpathogenic bacteria on plant growth in natural and agricultural ecosystems is discussed. In some natural ecosystems, evidence supports the view that in the vicinity of some allelopathically active perennials (e.g., Adenostoma fasciculatum, California), in addition to allelochemicals leached from the shrub's canopy, accumulation of phytotoxic bacteria or other allelopathic microorganisms amplify retardation of annuals. In agricultural ecosystems allelopathic bacteria may evolve in areas where a single crop is grown successively, and the resulting yield decline cannot be restored by application of minerals. Transfer of soils from areas where crop suppression had been recorded into an unaffected area induced crop retardation without readily apparent symptoms of plant disease. Susceptibility of higher plants to deleterious rhizobacteria is often manifested in sandy or so-called skeletal soils. Evaluation of phytotoxic activity under controlled conditions, as well as ways to apply allelopathic bacteria in the field, is approached. The allelopathic effect may occur directly through the release of allelochemicals by a bacterium that affects susceptible plant(s) or indirectly through the suppression of an essential symbiont. The process is affected by nutritional and other environmental conditions, some may control bacterial density and the rate of production of allelochemicals. Allelopathic nonpathogenic bacteria include a wide range of genera and secrete a diverse group of plant growth-mediating allelochemicals. Although a limited number of plant growth-promoting bacterial allelochemicals have been identified, a considerable number of highly diversified growth-inhibiting allelochemicals have been isolated and characterized. Some species may produce more than one allelochemical; for example, three different phyotoxins, geldanamycin, nigericin, and hydanthocidin, were isolated from Streptomyces hygroscopicus. Efforts to introduce naturally produced allelochemicals as plant growth-regulating agents in agriculture have yielded two commercial herbicides, phosphinothricin, a product of Streptomyces viridochromogenes, and bialaphos from S. hygroscopicus. Many species of allelopathic bacteria that affect growth of higher plants are not plant specific, but some do exhibit specificity; for example, dicotyledonous plants were more susceptible to Pseudomonas putida than were monocotyledons. Differential susceptibility of higher plants to allelopathic bacteria was noted also in much lower taxonomical categories, at the subspecies level, in different cultivars of wheat, or of lettuce. Therefore, when test plants are employed to evaluate bacterial allelopathy, final evaluation must include those species that are assumed to be suppressed in nature. The release of allelochemicals from plant residues in plots of ‘continuous crop cultivation’ or from allelopathic living plants may induce the development of specific allelopathic bacteria. Both the rate by which a bacterium gains from its allelopathic activity through utilizing plant excretions, and the reasons for the developing of allelopathic bacteria in such habitats, are important goals for further research.     

细菌群体感应的蛋白质组学研究进展

细菌群体感应是指细菌能合成、释放和感应一些类激素小分子信号,从而调控群体行为并对其作出应答反应。介导细菌群体感应的信号分子有多种,它们参与调节细菌许多重要生物学功能。目前对此研究的主要手段是基因组学和转录组学。然而近年来,基因组测序技术的不断发展为另一种新兴方法——以比较和功能性为基础的蛋白质组学法奠定了基础。所不同的是,传统方法只能局限性研究某些基因或蛋白,而蛋白质组学法能检测出生物体基因表达的全部蛋白,它也因此逐渐受到人们的广泛关注。主要从研究较多的三类信号分子方面描述如何利用蛋白盾组举法解析细菌交流的“语言”。     

趋磁细菌的磁小体

趋磁细菌是一类对磁场有趋向性反应的细菌,其菌体能吸收外界环境中铁元素并在体内合成包裹有膜的纳米磁性颗粒Fe₃O₄或Fe₃O_{3S4晶体即磁小体。综述了趋磁细菌的磁小体生物矿化的条件,以及趋磁细菌的铁离子吸收、磁小体囊泡的形成、铁离子的转运到磁小体囊泡及囊泡中受控的Fe3O4生物矿化的分子生物学和生物化学等方面的研究进展,重点介绍了趋磁细菌磁小体合成机制的研究进展及未来研究磁小体的发展方向。}     

醋酸菌多相分类研究进展

醋酸菌是一大群革兰氏染色阴性、绝对好氧的细菌的总称, 能将乙醇或糖类不完全氧化为有机酸。醋酸菌的分类在近30年经历了很大变化, 早期的分类系统主要以表型和生化特征为基础。如今, 大多采用结合表型、化学分类法和基因型数据的多相分类法对醋酸菌进行分类。本文综述了醋酸菌的多相分类研究进展, 主要介绍了醋酸菌的现行分类情况及表型分类、化学分类和基因分型等方法在醋酸菌分类中的应用。     

红螺菌(Rhodospirillum sp.)的生长及其饥饿存活的研究

红螺菌（Ｒｈｏｄｏｐｉｒｉｌｌｕｍ ｓｐ．）是在多种不同生境中广泛存在的光合细菌中的一类,它在水产养殖上也得到了广泛应用。报道了不同生长阶段红螺菌在饥饿环境中的存添能力。红螺菌在饥饿环境中的存活能力提高。分批培养过程中,同时测定红螺菌数和可培养活菌数的变化表明,静止期生长期后的红螺菌难以在固体培养基上形成菌落,进入非可培养状态,进入非可培养状态的红螺菌经复苏培养后仍可恢复在固体培养基上形成菌落的能