Project description:Biofilm formation and type III secretion have been shown to be reciprocally regulated in P. aeruginosa, and it has been suggested that factors related to acute infection may be incompatible with biofilm formation. We investigated how growth conditions influence the production of virulence factors by studying the inter-relationships between colonies, biofilms and planktonic cells. We found that biofilms in our growth conditions express the type III secretion and these lifestyles are therefore not mutually exclusive in P. aeruginosa. Keywords: Comparison of different growth modes and growth phases of Pseudomonas aeruginosa
Project description:To investigate the gene expression profile of pellicle cells of Pseudomonas aeruginosa, microarray analysis was performed. Transcriptome profiles of pellicle cells and planktonic cells grown in LB medium were determined by Affymetrix GeneChip. Gene expression pattern that is specific to pellicle cells was evaluated by comparing the data set with that of planktonic cells. Pseudomonas aeruginosa wild type (PAO1ut) strain was cultivated aerobically in LB in Erlenmeyer flasks under static or shaking conditions, and total RNAs were extracted at 24 hours (static culture) and early stationary phase (OD600 = 1.4, shaking culture). The experiment was performed in duplicate independent cultures.
Project description:The goal of this study was to determine the impact of metal deprivation (such as the metal deprivation induced by calprotectin treatment) on the physiology of Pseudomonas aeruginosa under multiple growth conditions. The RNA-seq analysis was designed to reveal the impact of calprotectin treatment on P. aeruginosa physiology during planktonic growth.
Project description:Pseudomonas aeruginosa is a highly versatile bacterium capable of surviving and often thriving in stressful environmental conditions. Here we studied the effect of two environmental conditions, temperature and growth phase, on the P. aeruginosa PAO1 transcriptome. As P. aeruginosa is well-known for its growth-phase dependent phenotypes and gene regulation, our goal was to determine how temperature altered global gene expression at exponential versus stationary phase and to characterize how growth phase affects thermoregulation. To do this, we grew PAO1 in parallel at 25°C and 37°C and sampled the same populations first at exponential phase and then again at stationary phase and assessed gene expression by RNA-sequencing. We also grew PAO1 and an isogenic DlasR mutant at 25°C and 37°C and sampled populations at stationary phase to define LasR-regulated genes at each temperature by RNA-sequencing. This work provides a comprehensive thermoregulon for PAO1 at two distinct growth phases, as well as growth phase transcriptomics at two temperatures, and expands our understanding of quorum sensing regulation under different environmental conditions that P. aeruginosa encounters.
Project description:Pseudomonas aeruginosa is a highly versatile bacterium capable of surviving and often thriving in stressful environmental conditions. Here we studied the effect of two environmental conditions, temperature and growth phase, on the P. aeruginosa PAO1 transcriptome. As P. aeruginosa is well-known for its growth-phase dependent phenotypes and gene regulation, our goal was to determine how temperature altered global gene expression at exponential versus stationary phase and to characterize how growth phase affects thermoregulation. To do this, we grew PAO1 in parallel at 25°C and 37°C and sampled the same populations first at exponential phase and then again at stationary phase and assessed gene expression by RNA-sequencing. We also grew PAO1 and an isogenic DlasR mutant at 25°C and 37°C and sampled populations at stationary phase to define LasR-regulated genes at each temperature by RNA-sequencing. This work provides a comprehensive thermoregulon for PAO1 at two distinct growth phases, as well as growth phase transcriptomics at two temperatures, and expands our understanding of quorum sensing regulation under different environmental conditions that P. aeruginosa encounters.
Project description:We studied adaptation of the metabolically versatile bacterium Pseudomonas aeruginosa to standard laboratory conditions by propagating mismatch repair-deficient P. aeruginosa in exponential phase for 24 days in rich medium. In the selective environment of this large-bottleneck mutation accumulation experiment, the bacteria developed shorter lag phases, higher growth rates and higher maximum cell densities. Transcriptional profiling and phenotyping for growth in different media revealed that higher fitness under laboratory conditions evolved via different pathways. Although common adaptive mutations or mutations that define trade-offs were not identified, there was a convergent evolution of transcriptional profiles associated with a shift from biofilm-associated to planktonic lifestyles. Our results indicate that under constant planktonic conditions P. aeruginosa uses several genetic pathways in order to fine-tune adaptation towards faster growth. The selected mutations in the different genetic pathways show a great variety of biofilm, virulence and motility phenotypic trade-offs, thus implying that on the population level, the adaptation of P. aeruginosa to constant conditions does not compromise its versatility. Methods: mRNA profiles were generated for Pseudomonas aeruginosa samples derived from LB-cultures grown to an OD600 =0.4-0.6. The removal of ribosomal RNA was performed using the Ribo-Zero Bacteria Kit (Illumina) and cDNA libraries were generated with the ScriptSeq v2 Kit (Illumina). The samples were sequenced in single end mode on an Illumina HiSeq 2500 device and mRNA reads were trimmed and mapped to the NC_008463.1 (PA14) reference genome from NCBI using Stampy pipeline with default settings.
Project description:Comparison of Pseudomonas aeruginosa planktonic cultures and bacterial biofilms grown under variations in growth media to demonstrate carbon catabolite repression phenomena using bottom-up proteomics
Project description:Biofilm formation and type III secretion have been shown to be reciprocally regulated in P. aeruginosa, and it has been suggested that factors related to acute infection may be incompatible; with biofilm formation. We investigated how growth conditions influence the production of virulence factors by studying the inter-relationships between colonies, biofilms and planktonic cells. We found that biofilms in our growth conditions express the type III secretion and these lifestyles are therefore not mutually exclusive in P. aeruginosa. Experiment Overall Design: Pseudomonas aeruginosa cells grown in five different conditions were analysed with three biological replicates for each sample. The five different conditions were planktonic cells in exponential phase, planktonic cells in stationary phase, colonies on agar plates incubated for 15 or 40 hours and biofilms in a continuous flow system after three days of growth.
Project description:Virulent bacteriophages (or phages) are viruses that specifically infect and lyse a bacterial host. When multiple phages co-infect a bacterial host, the extent of lysis, dynamics of bacteria-phage and phage-phage interactions are expected to vary. The objective of this study is to identify the factors influencing the interaction of two virulent phages with different Pseudomonas aeruginosa growth states (planktonic, an infected epithelial cell line, and biofilm) by measuring the bacterial time-kill and individual phage replication kinetics. A single administration of phages effectively reduced P. aeruginosa viability in planktonic conditions and infected human lung cell cultures, but phage-resistant variants subsequently emerged. In static biofilms, the phage combination displayed initial inhibition of biofilm dispersal, but sustained control was achieved only by combining phages and meropenem antibiotic. In contrast, adherent biofilms showed tolerance to phage and/or meropenem, suggesting a spatiotemporal variation in the phage-bacterial interaction. The kinetics of adsorption of each phage to P. aeruginosa during single- or co-administration were comparable. However, the phage with the shorter lysis time depleted bacterial resources early and selected a specific nucleotide polymorphism that conferred a competitive disadvantage and cross-resistance to the second phage. The extent and strength of this phage-phage competition and genetic loci conferring phage resistance, are, however, P. aeruginosa genotype dependent. Nevertheless, adding phages sequentially resulted in their unimpeded replication with no significant increase in bacterial host lysis. These results highlight the interrelatedness of phage-phage competition, phage resistance and specific bacterial growth state (planktonic/biofilm) in shaping the interplay among P. aeruginosa and virulent phages.
Project description:. The transition of the opportunistic pathogen Pseudomonas aeruginosa from free-living bacteria into surface-associated biofilm communities represents a viable target for the prevention and treatment of chronic infectious disease. We have established a proteomics platform that identified 2443 and 1142 high-confidence proteins in P. aeruginosa whole cells and outer membrane vesicles (OMVs), respectively, at three time points during biofilm development. Analysis of cellular systems, specifically the phenazine biosynthetic pathway, demonstrates that whole cell protein abundance correlates to end product (i.e., pyocyanin) concentrations in biofilm but not planktonic cultures. Furthermore, increased cellular protein abundance in this pathway results in quantifiable pyocyanin in early biofilm OMVs, and OMVs from both growth modes isolated at later time points. Overall, our data indicate that the OMVs being released from the surface of the biofilm whole cells have unique proteomes in comparison to their planktonic counterparts. The relative abundance of OMV proteins from various subcellular sources showed considerable differences between the two growth modes over time, supporting the existence and preferential activation of multiple OMV biogenesis mechanisms under different conditions. The consistent detection of cytoplasmic proteins in the OMV subproteome suggests that these proteins may contribute a small but functionally relevant component to biofilm OMVs. Direct comparisons of outer membrane protein abundance levels between OMVs and whole cells shows ratios that vary greatly from 1:1, and supports previous studies that advocate specific inclusion, or “packaging”, of proteins into OMVs. The detailed analysis of packaged protein groups indicates biogenesis mechanisms that involve untethered, rather than absent, peptidoglycan-binding proteins. Collectively, individual protein and biological system analyses of biofilm OMVs show that drug-binding cytoplasmic proteins and porins are shuttled from the whole cell into the OMVs, potentially contributing to the antibiotic resistance of P. aeruginosa whole cells within biofilms.