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Investigates the bacterial cell surface motility during the migration of populations of the Serratia liquefaciens MG1. Bacterial surface translocation; Forms; Description of swimming and swarming motility; Regulatory systems; Includes flagellar master and quorum-sensing system control.

Presents a study of a gene which is homologous to the rpoS gene of Escherichia Coli which was cloned from Pseudomonas putida KT2440. Information on the cloning, sequencing and phenotypic characterization of the rpoS gene; Efforts to correlate the increased resistance of Pseudomonas putida to general stress; Questions whether the transcription factors is responsible for the protein synthesis program displayed as cella stop growing.

Reports that changes in rRNA levels during stress invalidates results from mRNA blotting. Investigation of mRNA synthesis rates; Estimation by fluorescence in situ hybridization of 16S and 23S rRNA levels in single cells during heat shock; Limitations of RNA blotting techniques.

Pseudomonas putida strains are generally recognized as solvent tolerant, exhibiting varied sensitivity to organic solvents. Pan-genome analysis has revealed that 30% of genes belong to the core-genome of Pseudomonas. Accessory and unique genes confer high degree of adaptability and capabilities for the degradation and synthesis of a wide range of chemicals. For the use of these microbes in bioremediation and biocatalysis, it is critical to understand the mechanisms underlying these phenotypic differences. In this study, RNA-seq analysis compared the short- and long-term responses of the toluene-sensitive KT2440 strain and the highly tolerant DOT-T1E strain. The sensitive strain activates a larger number of genes in a higher magnitude than DOT-T1E. This is expected because KT2440 bears one toluene tolerant pump, while DOT-T1E encodes three of these pumps. Both strains activate membrane modifications to reduce toluene membrane permeability. The KT2440 strain activates the TCA cycle to generate energy, while avoiding energy-intensive processes such as flagellar biosynthesis. This suggests that KT2440 responds to toluene by focusing on survival mechanisms. The DOT-T1E strain activates toluene degradation pathways, using toluene as source of energy. Among the unique genes encoded by DOT-T1E is a 70 kb island composed of genes of unknown function induced in response to toluene. [ABSTRACT FROM AUTHOR]

The article describes a high-throughput assay to identify substances that reduce the frequency of conjugation in Gram-negative bacteria. An automated conjugation assay was developed that used plasmid R388 and a laboratory strain of Escherichia coli as a model system, and bioluminescence as a reporter for conjugation activity. Two separate compounds were identified from the factions, linoleic acid and dehydrocrepenynic acid. Downstream analysis showed that the chemical class of unsaturated fatty acids act as true inhibitors of conjugation.

Traditional treatment of infectious diseases is based on compounds that kill or inhibit growth of bacteria. A major concern with this approach is the frequent development of resistance to antibiotics. The discovery of communication systems (quorum sensing systems) regulating bacterial virulence has afforded a novel opportunity to control infectious bacteria without interfering with growth. Compounds that can override communication signals have been found in the marine environment. Using Pseudomonas aeruginosa PAO1 as an example of an opportunistic human pathogen, we show that a synthetic derivate of natural furanone compounds can act as a potent antagonist of bacterial quorum sensing. We employed GeneChip® microarray technology to identify furanone target genes and to map the quorum sensing regulon. The transcriptome analysis showed that the furanone drug specifically targeted quorum sensing systems and inhibited virulence factor expression. Application of the drug to P.aeruginosa biofilms increased bacterial susceptibility to tobramycin and SDS. In a mouse pulmonary infection model, the drug inhibited quorum sensing of the infecting bacteria and promoted their clearance by the mouse immune response. [ABSTRACT FROM AUTHOR]

A presumed antimicrobial enzyme system, the Curvularia haloperoxidase system, was examined with the aim of evaluating its potential as a sanitizing agent. In the presence of hydrogen peroxide, Curvularia haloperoxidase facilitates the oxidation of halides, such as chloride, bromide, and iodide, to antimicrobial compounds. The Curvularia haloperoxidase system caused several-log-unit reductions in counts of bacteria (Pseudomonas spp., Escherichia coli, Serratia marcescens, Aeromonas salmonicida, Shewanella putrefaciens, Staphylococcus epidermidis, and Listeria monocytogenes), yeasts (Candida sp. and Rhodotorula sp.), and filamentous fungi (Aspergillus niger, Aspergillus tubigensis, Aspergillus versicolor, Fusarium oxysporum, Penicillium chrysogenum, and Penicillium paxilli) cultured in suspension. Also, bacteria adhering to the surfaces of contact lenses were killed. The numbers of S. marcescens and S. epidermidis cells adhering to contact lenses were reduced from 4.0 and 4.9 log CFU to 1.2 and 2.7 log CFU, respectively, after treatment with the Curvularia haloperoxidase system. The killing effect of the Curvularia haloperoxidase system was rapid, and 10[sup 6] CFU of E. coli cells/ml were eliminated within 10 min of treatment. Furthermore, the antimicrobial effect was short lived, causing no antibacterial effect against E. coli 10 min after the system was mixed. Bovine serum albumin (1%) and alginate (1%) inhibited the antimicrobial activity of the Curvularia haioperoxidase system, whereas glucose and Tween 20 did not affect its activity. In conclusion, the Curvularia haloperoxidase system is an effective sanitizing system and has the potential for a vast range of applications, for instance, for disinfection of contact lenses or medical devices. [ABSTRACT FROM AUTHOR]

Discusses the cloning and molecular characterization of an N-acylhomoserine lactone-dependent quorum-sensing system in Pseudomonas putida strain IsoF. Dependence of the expression of ppuI on positive feedback regulation; Results of the sequence analysis of the DNA regions flanking ppuI and ppuR.

Investigates the inhibition of quorum sensing in Pseudomonas aeruginosa biofilm bacteria. Specification of tools for in situ detection of N-acyl homoserine lactone (AHL)-mediated quorum sensing; Role of synthetic halogenated furanone compound in the expression of PlasB-gfp reporter fusion; Effect of the compound on biofilm architecture.

Examines the pseudomonas aeruginosa and burkholderia cepacia in the lungs of cystic fibrosis patients. Employment of N-acylhomoserine lactone signal (AHL) in the expression of virulence factors; Construction and characterization of the in situ detection of AHL; Unidirectional signalling between the two strains.

Investigates the effect of alginate overproduction to the Pseudomonas aeruginosa biofilm structure and function. Conversion of P. aeruginosa to a mucoid phenotype cystic fibrosis infections; Description of P. aeruginosa infections; Importance of biofilm formation and the conversion to mucoidy in the aspects of CF pathogenesis.

Reports that the cep quorom-sensing system of the pathogenic bacterium Burkholderia cepacia H111 controls biofilm formation an swarming motility. Construction and characterization of defined Burkholderia cepacia H111 cep mutants; Involvement of swarming motility in the process of biofilm formation by burkholderia cepacia; Existence of Burkholderia cepacia in the lungs of patients suffering from cystic fibrosis.

Assesses the Green Fluorescent Protein (GFP) fluorescence in cells of Streptococcus gordoni. Demonstration of the homogeneous expressions of the gfpmut3; Determination of oxygen concentration for GFP fluorophore maturation.

Polyphosphate- and polyhydroxyalkanoate (PHA)- accumulating traits of predominant microorganisms in an efficient enhanced biological phosphorus removal (EBPR) process were investigated system- atically using a suite of non-culture-dependent methods. Results of 16S rDNA clone library and fluorescence in situ hybridization (FISH) with rRNA- targeted, group-specific oligonucleotide probes indi- cated that the microbial community consisted mostly of the α- (9.5% of total cells), β- (41.3%) and γ- (6.8%) subclasses of the class Proteobacteria, Flexibacter ± Cytophaga (4.5%) and the Gram-positive high G1C (HGC) group (17.9%). With individual phylogenetic groups or subgroups, members of Candidatus Accu- mulibacter phosphatis in the b-2 subclass, a novel HGC group closely related to Tetrasphaera spp., and a novel g-proteobacterial group were the predomi- nant populations. Furthermore, electron microscopy with energy-dispersive X-ray analysis was used to validate the staining specificity of 4,6-diamino-2- phenylindole (DAPI) for intracellular polyphosphate and revealed the composition of polyphosphate granules accumulated in predominant bacteria as mostly P, Ca and Na. As a result, DAPI and PHA staining procedures could be combined with FISH to identify directly the polyphosphate- and PHA- accumulating traits of different phylogenetic groups. Members of Accumulibacter phosphatis and the... [ABSTRACT FROM AUTHOR]

Presents a study which employed genetic approaches combined with an analysis of the pattern of protein synthesis to test hypothesis. Analysis if gene expression; Conclusions reached.

Examines the expression of a lactose operon in Salmonella typhimurium single cells using lactose messenger RNA targeting in situ reverse transcription-polymerase chain reaction. Transcription of lactose operon; Beta-galactosidase activity of the cells; Role of lactose permease in generating non-heterogeneity in sub-optimally induced cultures of Lac[sub +] cells.

Summary Chronic Pseudomonas aeruginosa infections evade antibiotic therapy and are associated with mortality in cystic fibrosis (CF) patients. We find that in vitro resistance evolution of P. aeruginosa toward clinically relevant antibiotics leads to phenotypic convergence toward distinct states. These states are associated with collateral sensitivity toward several antibiotic classes and encoded by mutations in antibiotic resistance genes, including transcriptional regulator nfxB . Longitudinal analysis of isolates from CF patients reveals similar and defined phenotypic states, which are associated with extinction of specific sub-lineages in patients. In-depth investigation of chronic P. aeruginosa populations in a CF patient during antibiotic therapy revealed dramatic genotypic and phenotypic convergence. Notably, fluoroquinolone-resistant subpopulations harboring nfxB mutations were eradicated by antibiotic therapy as predicted by our in vitro data. This study supports the hypothesis that antibiotic treatment of chronic infections can be optimized by targeting phenotypic states associated with specific mutations to improve treatment success in chronic infections. [ABSTRACT FROM AUTHOR]

Summary Chronic Pseudomonas aeruginosa infections evade antibiotic therapy and are associated with mortality in cystic fibrosis (CF) patients. We find that in vitro resistance evolution of P. aeruginosa toward clinically relevant antibiotics leads to phenotypic convergence toward distinct states. These states are associated with collateral sensitivity toward several antibiotic classes and encoded by mutations in antibiotic resistance genes, including transcriptional regulator nfxB . Longitudinal analysis of isolates from CF patients reveals similar and defined phenotypic states, which are associated with extinction of specific sub-lineages in patients. In-depth investigation of chronic P. aeruginosa populations in a CF patient during antibiotic therapy revealed dramatic genotypic and phenotypic convergence. Notably, fluoroquinolone-resistant subpopulations harboring nfxB mutations were eradicated by antibiotic therapy as predicted by our in vitro data. This study supports the hypothesis that antibiotic treatment of chronic infections can be optimized by targeting phenotypic states associated with specific mutations to improve treatment success in chronic infections. [ABSTRACT FROM AUTHOR]