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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]

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]

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]

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.