BACKGROUND & AIMS: :A strain of Pseudomonas aeruginosa isolated from a site contaminated with refined oil products exhibited demulsification capabilities against Tween 80-Span 80 stabilized oil-in-water (O/W), Tween 80-stabilized water-in-oil (W/O) model emulsions (kerosene-water), and an industrial emulsion (Daido Dairoll PA-5A). GC-MS analysis confirmed the presence of fatty acids and carbohydrates in the extracellular biodemulsifier. The demulsifying activity of cells and culture supernatants was favored by growth in media containing 1% diesel oil. There was a correlation between culture age, de-emulsification and cellular hydrophobicity, and highest activities were observed for cells and supernatants from 96-h cultures. Activity increased with addition of up to 60 mg cells or 300 μL supernatant to emulsions. The activity was relatively stable at 20-40 °C and to freezing, but was reduced by 69% by washing the cells with chloroform-methanol-water. This demulsifier has potential for application in biotreatment of emulsified oily wastewaters to promote recovery and/or degradation of oil.

背景与目标： : 从被成品油污染的地点分离出的铜绿假单胞菌菌株对Tween 80-Span 80稳定水包油 (O/W)，Tween 80稳定油包水 (W/O) 模型乳液 (煤油-水) 具有破乳能力，和一种工业乳液 (Daido Dairoll PA-5A)。Gc-ms分析证实了细胞外生物破乳剂中脂肪酸和碳水化合物的存在。在含有1% 柴油的培养基中生长有利于细胞和培养上清液的破乳活性。培养年龄，去乳化和细胞疏水性之间存在相关性，并且观察到96小时培养物中细胞和上清液的最高活性。随着向乳液中添加高达60 mg细胞或300 μ l上清液，活性增加。该活性在20-40 °C下相对稳定至冷冻，但通过用氯仿-甲醇-水洗涤细胞而69% 降低。该破乳剂具有在乳化含油废水的生物处理中应用的潜力，以促进油的回收和/或降解。

BACKGROUND & AIMS: :The development of antibiotic resistance in the opportunistic pathogen Pseudomonas aeruginosa is a major cause of the pathogen's morbidity and is strongly correlated with the biofilm formation. Motility and adherence capacity in long-term stressed cells have not been extensively analyzed even though P. aeruginosa considered a model organism for the study of biofilm formation. In this investigation, P. aeruginosa ATCC 27853 strain has been stored for 12 months in LB broth with 0.5 M NaCl. Several experiments demonstrated that the strain recovery from the salty microcosm had the ability to increase the biofilm formation and to reduce motility comparing with that of the original strain. To identify genes involved in the regulation of biofilm and/or in stress response by the recovered P. aeruginosa, differential display "DDRT-PCR" technique was used. The genes speD and ccoN2, coding, respectively, for an S-adenosylmethionine decarboxylase and Cbb3-type cytochrome oxidase, were identified in recovered strain of P. aeruginosa ATCC 27853 as two differentially expressed gene fragments. A comparison of the biofilm produced by the wild-type strain PA14 and the transposon insertion mutant for speD gene suggested that spermidine has a potential role in the adaptive response in P. aeruginosa incubated in long-term stress conditions.

背景与目标： : 机会性病原体铜绿假单胞菌中抗生素耐药性的发展是病原体发病的主要原因，并且与生物膜的形成密切相关。尽管铜绿假单胞菌被认为是研究生物膜形成的模式生物，但长期应激细胞的运动和粘附能力尚未得到广泛分析。在这项研究中，铜绿假单胞菌ATCC 27853菌株已在含有0.5 M NaCl的LB肉汤中储存12个月。几项实验表明，与原始菌株相比，从咸微观世界中恢复的菌株具有增加生物膜形成并降低运动性的能力。为了鉴定与回收的铜绿假单胞菌调节生物膜和/或应激反应有关的基因，使用了差异显示 “ddrt-pcr” 技术。在回收的铜绿假单胞菌ATCC 27853菌株中鉴定了分别编码S-腺苷甲硫氨酸脱羧酶和Cbb3-type细胞色素氧化酶的基因speD和ccoN2，作为两个差异表达的基因片段。对野生型菌株PA14和speD基因转座子插入突变体产生的生物膜的比较表明，亚精胺在长期胁迫条件下培养的铜绿假单胞菌的适应性反应中具有潜在作用。

BACKGROUND & AIMS: :A strain of Pseudomonas stutzeri was isolated form an enrichment of perchlorate reducing bacteria from the formation water collected from an Indian coalbed which solubilized coal and produced copious amount of biosurfactant when coal was added to the medium. It produced maximum biosurfactant with lignite coal followed by olive oil and soybean oil which was able to emulsify several aromatic hydrocarbons including kerosene oil, diesel oil, hexane, toluene etc. Haemolytic test, growth inhibition of Bacillus subtilis and FTIR analysis showed rhamnolipid nature of the biosurfactant. The stability of the coal induced biosurfactant in pH range of 4-8 and up to 25% NaCl concentration and 100 °C temperature suggests that due to its ability to produce biosurfactant and solubilize coal P. stutzeri may be useful in the coalbed for in situ biotransformation of coal into methane and in the bioremediation of PAHs from oil contaminated sites including marine environments.

背景与目标： : 从印度煤层收集的地层水中分离出一株stutzeri假单胞菌，富集高氯酸盐还原细菌，当将煤添加到培养基中时，该地层水溶解了煤并产生了大量的生物表面活性剂。它用褐煤和橄榄油和大豆油产生最大的生物表面活性剂，能够乳化几种芳香烃，包括煤油，柴油，己烷，甲苯等。溶血试验，枯草芽孢杆菌的生长抑制和FTIR分析显示了生物表面活性剂的鼠李糖脂性质。煤诱导的生物表面活性剂在4-8的pH范围内以及高达25% 的NaCl浓度和100 °C的温度下的稳定性表明，由于其能够产生生物表面活性剂和溶解煤P. stutzeri可能在煤层中用于将煤原位生物转化为甲烷以及在PAHs的生物修复中石油污染场地，包括海洋环境。

BACKGROUND & AIMS: :Culturomics is a new postgenomics field that explores the microbial diversity of the human gut coupled with taxono-genomic strategy. Culturomics, and the microbiome science more generally, are anticipated to transform global health diagnostics and inform the ways in which gut microbial diversity contributes to human health and disease, and by extension, to personalized medicine. Using culturomics, we report in this study the description of strain CB1T ( = CSUR P1334 = DSM 29075), a new species isolated from a stool specimen from a 37-year-old Brazilian woman. This description includes phenotypic characteristics and complete genome sequence and annotation. Strain CB1T is a gram-negative aerobic and motile bacillus, exhibits neither catalase nor oxidase activities, and presents a 98.3% 16S rRNA sequence similarity with Pseudomonas putida. The 4,723,534 bp long genome contains 4239 protein-coding genes and 74 RNA genes, including 15 rRNA genes (5 16S rRNA, 4 23S rRNA, and 6 5S rRNA) and 59 tRNA genes. Strain CB1T was named Pseudomonas massiliensis sp. nov. and classified into the family Pseudomonadaceae. This study demonstrates the usefulness of microbial culturomics in exploration of human microbiota in diverse geographies and offers new promise for incorporating new omics technologies for innovation in diagnostic medicine and global health.

背景与目标： : Culturomics是一个新的后基因组学领域，探索人类肠道的微生物多样性以及taxono基因组策略。预计文化学和更广泛的微生物组科学将改变全球健康诊断，并告知肠道微生物多样性对人类健康和疾病的贡献方式，并进而扩展到个性化医学。使用文化学，我们在这项研究中报告了菌株CB1T (  =  CSUR P1334   =  DSM 29075) 的描述，该菌株是从一名37岁巴西妇女的粪便标本中分离出来的新物种。此描述包括表型特征和完整的基因组序列和注释。菌株CB1T是革兰氏阴性需氧和活动芽孢杆菌，既不显示过氧化氢酶也不显示氧化酶活性，并且与恶臭假单胞菌呈现98.3% 的16S rRNA序列相似性。4,723,534  bp长基因组包含4239个蛋白质编码基因和74个RNA基因，包括15个rRNA基因 (5个16S rRNA，4个23S rRNA和6个5S rRNA) 和59个tRNA基因。菌株CB1T被命名为马11月假单胞菌而被归类于假单胞菌科。这项研究证明了微生物文化在探索不同地理区域的人类微生物区系中的有用性，并为结合新的组学技术在诊断医学和全球健康领域的创新提供了新的希望。

BACKGROUND & AIMS: :Surface-associated microbial communities in many cases display dynamic developmental patterns. Model biofilms formed by Pseudomonas aeruginosa and Pseudomonas putida in laboratory flow-chamber setups represent examples of such behaviour. Dependent on the experimental conditions the bacteria in these model biofilms develop characteristic multicellular structures through a series of distinct steps where cellular migration plays an important role. Despite the appearance of these characteristic developmental patterns in the model biofilms the available evidence suggest that the biofilm forming organisms do not possess comprehensive genetic programs for biofilm development. Instead the bacteria appear to have evolved a number of different mechanisms to optimize surface colonization, of which they express a subset in response to the prevailing environmental conditions. These mechanisms include the ability to regulate cellular adhesiveness and migration in response to micro-environmental signals including those secreted by the bacteria themselves.

背景与目标： : 表面相关微生物群落在许多情况下显示出动态的发育模式。在实验室流动室设置中，铜绿假单胞菌和恶臭假单胞菌形成的模型生物膜代表了这种行为的例子。根据实验条件，这些模型生物膜中的细菌通过一系列不同的步骤发展出特征性的多细胞结构，其中细胞迁移起着重要作用。尽管在模型生物膜中出现了这些特征性的发育模式，但现有证据表明，形成生物膜的生物不具备用于生物膜发育的综合遗传程序。相反，细菌似乎已经进化出许多不同的机制来优化表面定植，它们表达了对当前环境条件的响应。这些机制包括响应微环境信号 (包括细菌本身分泌的信号) 调节细胞粘附性和迁移的能力。

BACKGROUND & AIMS: :Pseudomonas aeruginosa PACL strain, isolated from oil-contaminated soil taken from a lagoon, was used to investigate the efficiency and magnitude of biosurfactant production, using different waste frying soybean oils, by submerged fermentation in stirred tank reactors of 6 and 10 l capacities. A complete factorial experimental design was used, with the goal of optimizing the aeration rate (0.5, 1.0, and 1.5 vvm) and agitation speed (300, 550, and 800 rpm). Aeration was identified as the primary variable affecting the process, with a maximum rhamnose concentration occurring at an aeration rate of 0.5 vvm. At optimum levels, a maximum rhamnose concentration of 3.3 g/l, an emulsification index of 100%, and a minimum surface tension of 26.0 dynes/cm were achieved. Under these conditions, the biosurfactant production derived from using a mixture of waste frying soybean oil (WFSO) as a carbon source was compared to production when non-used soybean oil (NUSO), or waste soybean oils used to fry specific foods, were used. NUSO produced the highest level of rhamnolipids, although the waste soybean oils also resulted in biosurfactant production of 75-90% of the maximum value. Under ideal conditions, the kinetic behavior and the modeling of the rhamnose production, nutrient consumption, and cellular growth were established. The resulting model predicted data points that corresponded well to the empirical information.

背景与目标： : 铜绿假单胞菌PACL菌株是从泻湖中提取的受油污染的土壤中分离出来的，用于研究使用不同的废油炸大豆油在6和10 l的搅拌釜反应器中进行深层发酵的生物表面活性剂生产的效率和规模容量。使用了完整的析因实验设计，目的是优化曝气速率 (0.5，1.0和1.5 vvm) 和搅拌速度 (300，550和800 rpm)。曝气被确定为影响该过程的主要变量，最大鼠李糖浓度发生在0.5 vvm的曝气速率下。在最佳水平下，最大鼠李糖浓度为3.3g/l，乳化指数为100%，最小表面张力为26.0 dynes/cm。在这些条件下，将使用废油炸大豆油 (WFSO) 混合物作为碳源的生物表面活性剂生产与使用非用大豆油 (NUSO) 或用于油炸特定食品的废大豆油的生产进行了比较。NUSO产生了最高水平的鼠李糖脂，尽管废大豆油也导致生物表面活性剂产生了最大值的75-90%。在理想条件下，建立了鼠李糖生产，养分消耗和细胞生长的动力学行为和模型。生成的模型预测了与经验信息非常对应的数据点。

BACKGROUND & AIMS: :Pseudomonas aeruginosa is a gram-negative opportunistic pathogen that is cytotoxic towards a variety of eukaryotic cells. To investigate the effect of this bacterium on monocyte, we infected human U937 cells with the P. aeruginosa strain in vitro. To explore the expression of Bcl-2 and Bax as well as caspase-3/9 activation in the apoptosis of human U937 cells induced by P. aeruginosa, Hoechst 33258 staining and Giemsa staining as well as Flow cytometry analysis were used to determine the rate of apoptosis, and the expressions of Bcl-2 and Bax were assayed by RT-PCR and Western blotting respectively. Bax protein conformation change was assayed by immunoprecipitation. Cytochrome c release was measured by Western blotting. Moreover, exposure of U937 cells to P. aeruginosa measured caspase-3/9 activity. It was found that the apoptosis of human U937 cells could be induced by Pseudomonas aeruginosa in a dose- and time-dependent manner. Also, there were a tendency of alterations with an increased expression level of Bax and a reduced expression level of Bcl-2, increased levels of cytochrome c release, and also with an increased activation of caspase-3/9 and Bax protein conformation change. For the evaluation of the role of caspases, caspase-3/9 inhibitors Z-DEVD-FMK and Z-LEHD-FMK respectively were used. The results were further confirmed by the observation that the caspase inhibitors Z-DEVD-FMK and Z-LEHD-FMK blocked P. aeruginosa-induced U937 apoptosis. It is concluded that P. aeruginosa can induce apoptosis with an up-regulated expression of Bax and a down-regulated expression of Bcl-2, which resulted in increased levels of cytochrome c release and increased caspase-3 and -9 in human U937 cells.

背景与目标： 铜绿假单胞菌是一种革兰氏阴性机会性病原体，对多种真核细胞具有细胞毒性。为了研究这种细菌对单核细胞的影响，我们在体外用铜绿假单胞菌菌株感染了人U937细胞。为探讨铜绿假单胞菌诱导人U937细胞凋亡中Bcl-2和Bax的表达以及caspase-3/9的激活，采用Hoechst 33258染色和Giemsa染色以及流式细胞仪分析测定凋亡率。用rt-pcr和Western blotting分别检测Bcl-2和Bax的表达。通过免疫沉淀测定Bax蛋白构象变化。通过蛋白质印迹法测量细胞色素c的释放。此外，暴露于铜绿假单胞菌的U937细胞可测量caspase-3/9活性。发现铜绿假单胞菌可以剂量和时间依赖性地诱导人U937细胞的凋亡。此外，随着Bax表达水平的增加和Bcl-2表达水平的降低，细胞色素c释放水平的增加以及caspase-3/9和Bax蛋白构象变化的增加，存在改变的趋势。为了评估半胱天冬酶的作用，分别使用caspase-3/9抑制剂Z-DEVD-FMK和Z-LEHD-FMK。观察结果进一步证实，caspase抑制剂Z-DEVD-FMK和Z-LEHD-FMK阻断了铜绿假单胞菌诱导的U937凋亡。结论铜绿假单胞菌可诱导凋亡，Bax表达上调，Bcl-2表达下调，导致人U937细胞细胞色素c释放水平升高，caspase-3和-9增加。

BACKGROUND & AIMS: :In this study, oxygen and nitrate regulation of transcription and subsequent protein expression of the unique narK1K2GHJI respiratory operon of Pseudomonas aeruginosa were investigated. Under the control of PLAC, P. aeruginosa was able to transcribe nar and subsequently express methyl viologen-linked nitrate reductase activity under aerobic conditions without nitrate. Modulation of PLAC through the LacI repressor enabled us to assess both transcriptional and posttranslational regulation by oxygen during physiological whole-cell nitrate reduction.

背景与目标： : 在这项研究中，研究了铜绿假单胞菌独特的narK1K2GHJI呼吸操纵子的氧和硝酸盐对转录的调节以及随后的蛋白表达。在PLAC的控制下，铜绿假单胞菌能够转录nar，随后在有氧条件下无硝酸盐的情况下表达甲基紫精连接的硝酸还原酶活性。通过LacI阻遏物对PLAC的调节使我们能够评估生理全细胞硝酸盐还原过程中氧气的转录和翻译后调节。

BACKGROUND & AIMS: :Basic Violet 3 and Acid Blue 93 are the most important group of synthetic colourants extensively used in textile industries for dyeing cotton, wool, silk and nylon. Release of these dye pollutants in to the environment adversely affects the human health and aquatic organisms. The present study we used Pseudomonas putida MTCC 4910 for the adsorptive removal of Basic Violet 3 and Acid Blue 93 from the aqueous solutions. The pH (4-9) and NaCl concentrations (1mM-1M) did not influence the adsorption process. The equilibrium adsorption process fitted well to Freundlich model than Langmuir model. The kinetics of adsorption fitted well by pseudo-second-order. Thus in the present study an attempt has been made to exploit the dye removal capability of P. putida MTCC 4910, and it was found to be an efficient microbe that could be used for bio removal of dyes from textile effluents.

背景与目标： : 碱性紫罗兰3和酸性蓝93是最重要的合成着色剂组，广泛用于纺织工业中，用于棉，羊毛，丝绸和尼龙的染色。将这些染料污染物释放到环境中会对人类健康和水生生物产生不利影响。本研究使用恶臭假单胞菌MTCC 4910从水溶液中吸附去除碱性紫3和酸性蓝93。pH (4-9) 和NaCl浓度 (1mm-1m) 不影响吸附过程。平衡吸附过程比Langmuir模型更适合Freundlich模型。伪二阶吸附动力学拟合良好。因此，在本研究中，已经尝试利用P. putida MTCC 4910的染料去除能力，并且发现它是一种有效的微生物，可用于从纺织品流出物中生物去除染料。

BACKGROUND & AIMS: :Pseudomonas aeruginosa is a highly resistant opportunistic pathogen and an important etiological agent of various types of infections. During the last decade, P. aeruginosa phages have been extensively examined as alternative antimicrobial agents. The aim of the study was to determine antimicrobial effectiveness of combining subinhibitory concentrations of gentamicin, ceftriaxone, ciprofloxacin or polymyxin B with P. aeruginosa-specific bacteriophages belonging to families Podoviridae and Siphoviridae. The time-kill curve method showed that a combination of bacteriophages and subinhibitory concentrations of ceftriaxone generally reduced bacterial growth, and synergism was proven for a Siphoviridae phage σ-1 after 300 min of incubation. The detected alteration in morphology after ceftriaxone application, resulting in cell elongation, along with its specific mode of action, seemed to be a necessary but was not a sufficient reason for phage-antibiotic synergism. The phenomenon offers an opportunity for future development of treatment strategies for potentially lethal infections caused by P. aeruginosa.

背景与目标： : 铜绿假单胞菌是一种高度耐药的机会致病菌，是各种类型感染的重要病原体。在过去的十年中，铜绿假单胞菌噬菌体已被广泛研究为替代抗菌剂。该研究的目的是确定将亚抑制浓度的庆大霉素，头孢曲松，环丙沙星或多粘菌素b与属于Podoviridae和Siphoviridae家族的铜绿假单胞菌特异性噬菌体相结合的抗菌效果。时间杀伤曲线方法表明，噬菌体和亚抑菌浓度的头孢曲松的组合通常会降低细菌的生长，并且在孵育300分钟后证明了Siphoviridae噬菌体 σ-1的协同作用。头孢曲松应用后检测到的形态变化，导致细胞伸长及其特定的作用方式，似乎是必要的，但不是噬菌体-抗生素协同作用的充分理由。该现象为未来发展由铜绿假单胞菌引起的潜在致命感染的治疗策略提供了机会。

BACKGROUND & AIMS: :Plant pathogenic Pseudomonas syringae produce the hydroxy-β-lactam antimetabolite tabtoxinine-β-lactam (TβL) as a time-dependent inactivating glutamine analogue of plant glutamine synthetases. The producing pseudomonads use multiple modes of self-protection, two of which are characterized in this study. The first is the dipeptide ligase TblF which converts tabtoxinine-β-lactam to the TβL-Thr dipeptide known as tabtoxin. The dipeptide is not recognized by glutamine synthetase. This represents a Trojan Horse strategy: the dipeptide is secreted, taken up by dipeptide permeases in neighboring cells, and TβL is released by peptidase action. The second self-protection mode is elaboration by the acetyltransferase Ttr, which acetylates the α-amino group of the proximal inactivator TβL, but not the tabtoxin dipeptide.

背景与目标： : 植物致病性丁香假单胞菌产生羟基-β-内酰胺抗代谢物tabtoxinine-β-内酰胺 (t β l)，作为植物谷氨酰胺合成酶的时间依赖性失活谷氨酰胺类似物。产生的假单胞菌使用多种自我保护模式，本研究对其中两种模式进行了表征。第一种是二肽连接酶TblF，它将tabtoxinine-β-内酰胺转化为称为tabtoxin的TβL-Thr二肽。二肽不能被谷氨酰胺合成酶识别。这代表了特洛伊木马策略: 二肽被分泌，被邻近细胞中的二肽permeases所占据，而t β l通过肽酶作用被释放。第二种自我保护模式是通过乙酰基转移酶Ttr进行细化，该乙酰基转移酶使近端灭活因子t β l的 α-氨基乙酰化，但不使毒素二肽乙酰化。

BACKGROUND & AIMS: Growth of Pseudomonas aeruginosa ATCC 15692 was promoted when the strain was cultured in an iron-depleted succinate medium, supplemented with transferrin at 30%, 60% and 100% and lactoferrin at 60% and 100% iron-saturation. No significant differences between cell growth and pyoverdin production were observed when transferrin iron saturation was increased from 30% to 100%; however, cell growth and pyoverdin production were strongly dependent on lactoferrin iron saturation. Lower lactoferrin iron saturation (< 30%) resulted in more pyoverdin production and reduced cell growth. Incubation of pyoverdin (1.0 microM) with 10.0 microM transferrin (30%, 60% and 100% iron-saturated) or lactoferrin (60% and 100% iron-saturated) led to quenching of pyoverdin fluorescence. Also, 24 h incubation of pyoverdin (20.0 microM) with these two proteins (20.0 microM, 30%, 60% and 100% iron-saturated transferrin and 60% and 100% iron-saturated lactoferrin) at 25 degrees C resulted in increased absorbance at 460 nm. Both the fluorescence quenching and absorbance increases were iron-saturation-dependent. Taken together, these results support the conclusion that at physiological pH, P. aeruginosa pyoverdin can acquire from partially iron-saturated transferrin or lactoferrin.

背景与目标： 当菌株在贫铁琥珀酸培养基中培养时，促进铜绿假单胞菌ATCC 15692的生长，该培养基补充有30%，60% 和100% 的转铁蛋白和60% 和100% 的铁饱和度的乳铁蛋白。当转铁蛋白铁饱和度从30% 增加到100% 时，未观察到细胞生长和pyoverdin产生之间的显着差异; 然而，细胞生长和pyoverdin产生强烈依赖于乳铁蛋白铁饱和度。较低的乳铁蛋白铁饱和度 (< 30%) 导致更多的pyoverdin产生和降低的细胞生长。pyoverdin (1.0微米) 与10.0微米转铁蛋白 (30% 、60% 和100% 铁饱和) 或乳铁蛋白 (60% 和100% 铁饱和) 的孵育导致pyoverdin荧光的猝灭。此外，pyoverdin (20.0 microM) 与这两种蛋白质 (20.0 microM、30% 、60% 和100% 铁饱和转铁蛋白以及60% 和100% 铁饱和乳铁蛋白) 在25 ℃ 下孵育24小时导致在460 nm处的吸光度增加。荧光猝灭和吸光度的增加都是铁饱和度依赖性的。综上所述，这些结果支持以下结论: 在生理pH下，铜绿假单胞菌pyoverdin可以从部分铁饱和的转铁蛋白或乳铁蛋白中获得。

BACKGROUND & AIMS: :Cyclic diguanylate (c-di-GMP) is a broadly conserved bacterial signalling molecule that modulates diverse cellular processes, such as biofilm formation, colony morphology and swimming motility. The intracellular level of c-di-GMP is controlled by diguanylate cyclases (DGCs) with GGDEF domain and phosphodiesterases (PDEs) with either EAL or HD-GYP domain. Pseudomonas putida KT2440 has a large group of genes on its genome encoding proteins with GGDEF/EAL/HD-GYP domains. However, phenotypic-genotypic correlation and c-di-GMP metabolism of these genes were largely unknown. Herein, by systematically constructing deletion mutants/overexpression strains of the 42 predicted c-di-GMP metabolism-related genes and analysing the phenotypes, we preliminarily revealed the role of each gene in biofilm formation, colony morphology and swimming motility. Subsequent results from protein sequence alignments and cellular c-di-GMP assessment indicated that 25 out of the 42 genes were likely to encode DGCs, nine genes were predicted to encode PDEs, four genes encoded bifunctional enzymes and the other four genes encoded enzymatically inactive proteins. This study offers a basic understanding of the roles of these 42 genes and can serve as a toolkit for investigators to further elucidate the functions of these GGDEF and EAL/HD-GYP domain-containing proteins.

背景与目标： : 环二鸟苷酸 (c-di-GMP) 是一种广泛保守的细菌信号分子，可调节多种细胞过程，例如生物膜形成，菌落形态和游泳运动。c-di-GMP的细胞内水平由具有GGDEF结构域的双鸟苷酸环化酶 (dgc) 和具有EAL或HD-GYP结构域的磷酸二酯酶 (pde) 控制。恶臭假单胞菌KT2440在其基因组上有大量基因，编码具有GGDEF/EAL/hd-gyp结构域的蛋白质。然而，这些基因的表型-基因型相关性和c-di-GMP代谢在很大程度上是未知的。在此，通过系统构建42个预测的c-di-GMP代谢相关基因的缺失突变体/过表达菌株并分析表型，我们初步揭示了每个基因在生物膜形成，菌落形态和游泳运动中的作用。蛋白质序列比对和细胞c-di-GMP评估的后续结果表明，42个基因中有25个可能编码DGCs，预计有9个基因编码pde，4个基因编码双功能酶，其他4个基因编码酶无活性蛋白。这项研究提供了对这42个基因作用的基本理解，并可以作为研究人员进一步阐明这些GGDEF和EAL/hd-gyp结构域蛋白功能的工具包。

BACKGROUND & AIMS: BACKGROUND:Up to 90% of children develop Pseudomonas aeruginosa (Pa)-positive respiratory cultures after tracheotomy. OBJECTIVE:To identify the factors associated with chronic Pa-positive respiratory cultures in the first 2 years after tracheotomy. METHODS:We conducted a retrospective cohort study of 210 children ≤ 18 years old who underwent tracheotomy at a single freestanding children's hospital that had two or more years of respiratory cultures post-tracheotomy available for analysis. We conducted multivariable logistic regression to test the association between demographic and clinical factors to our primary outcome of chronic Pa infection, defined as > 75% of respiratory cultures positive for Pa in the first 2 years after tracheotomy. RESULTS:Of the primarily male (61%), Hispanic (68%), and publicly insured (88%) cohort, 18% (n = 37) developed chronic Pa-positive respiratory cultures in the first 2 years. On multivariable logistic regression, pre-tracheotomy Pa-positive respiratory culture (aOR 11.3; 95% CI 4-1.5) and discharge on beta agonist (aOR 6.3; 95% CI 1.1-36.8) were independently associated with chronic Pa-positive respiratory cultures, while discharge on chronic mechanical ventilation was associated with decreased odds (aOR 0.3; 95% CI 0.1-0.7). On sensitivity analysis examining those without a pre-tracheotomy Pa-positive respiratory culture, discharge on MV continued to be associated with decreased odds of chronic Pa (aOR 0.1; 95% CI 0.02-0.4) and three other variables (male gender, chronic lung disease, and discharge on inhaled corticosteroids) were associated with increased odds of chronic Pa. CONCLUSION:Because pre-tracheotomy Pa growth on respiratory culture is associated with post-tracheotomy chronic Pa-positive respiratory cultures, future research should examine pre-tracheotomy Pa eradication or suppression protocols.

背景与目标：

BACKGROUND & AIMS: :Denitrification and arginine fermentation are major parts of the anaerobic metabolism of Pseudomonas aeruginosa, which is important for biofilm formation and infection. The two-component regulatory system NarX-NarL is part of the underlying network and is required for denitrifying growth. All target promoters identified so far are activated by NarL. In this study the effect of NarL on arginine fermentation was investigated using proteome, Northern blot and lacZ reporter gene analyses. NarL-dependent repression of the arcDABC operon was observed and the corresponding NarL-binding site in the arcD promoter region was functionally localized at -60 bp upstream of the transcriptional start site using site-directed promoter mutagenesis and reporter gene fusion experiments. The results clearly show that in the presence of nitrate NarL represses the arginine-dependent activation of the arcDABC operon mediated by ArgR. It does not influence the oxygen-tension-dependent activation via Anr. Thus, the anaerobic energy metabolism of P. aeruginosa is coordinated via NarX-NarL activity. In the presence of nitrate the highly efficient denitrification is preferred over the less attractive arginine fermentation.

背景与目标： : 反硝化和精氨酸发酵是铜绿假单胞菌厌氧代谢的主要组成部分，对生物膜的形成和感染具有重要意义。两部分监管系统narx-narl是基础网络的一部分，是反硝化增长所必需的。到目前为止，所有鉴定的靶启动子都被NarL激活。在这项研究中，使用蛋白质组，Northern印迹和lacZ报告基因分析研究了NarL对精氨酸发酵的影响。使用定点启动子诱变和报告基因融合实验，观察到arcDABC操纵子的NarL依赖性抑制，并且arcD启动子区域中相应的NarL结合位点功能定位在转录起始位点上游-60 bp。结果清楚地表明，在存在硝酸盐的情况下，NarL抑制arcDABC操纵子的精氨酸依赖性激活。它不会通过Anr影响氧张力依赖性激活。因此，铜绿假单胞菌的厌氧能量代谢是通过NarX-NarL活性协调的。在硝酸盐存在下，与吸引力较小的精氨酸发酵相比，高效的反硝化作用是优选的。