Project description:This study examined the response of A. baumannii to cspC disruption via transposon mutagenesis. The goal was to gain insight into how a cold shock protein highly expressed within A. baumannii biofilms, CspC, functioned and identify pathways in which it may be involved.
Project description:In this study the transcriptomic changes occurring in A. baumannii ATCC 17978 in response to shock treament using the biocide chlorhexdine were determined. A. baumannii ATCC 17978 cells were grown at 37°C with shaking (200rpm) in 35mL cultures in MH broth to OD600=0.75, at which time they were split into 15mL cultures. One 15mL sample was treated with 4µg/mL chlorhexidine (0.5x MIC), whereas the other was not treated and used as a reference. Cultures were allowed to grow for a further 30 mins (to an average final OD600= ~1.35 for untreated cells and 1.25 for chlorhexidine treated samples), when cells were harvested by centrifugation and immediately suspended in Trizol reagent (Invitrogen). Total RNA was extracted using the PureLinkTM Micro-to-Midi Total RNA Purification kit (Invitrogen), incorporating an on-column DNAseI (Invitrogen) digestion. The experiment included using four grids of a custom Agilent 8 x 15000 spot microarray. Three biological replicates and one flip dye experiment.
Project description:In this study the transcriptomic changes occurring in A. baumannii ATCC 17978 in response to shock treament using the biocide chlorhexdine were determined. A. baumannii ATCC 17978 cells were grown at 37°C with shaking (200rpm) in 35mL cultures in MH broth to OD600=0.75, at which time they were split into 15mL cultures. One 15mL sample was treated with 4µg/mL chlorhexidine (0.5x MIC), whereas the other was not treated and used as a reference. Cultures were allowed to grow for a further 30 mins (to an average final OD600= ~1.35 for untreated cells and 1.25 for chlorhexidine treated samples), when cells were harvested by centrifugation and immediately suspended in Trizol reagent (Invitrogen). Total RNA was extracted using the PureLinkTM Micro-to-Midi Total RNA Purification kit (Invitrogen), incorporating an on-column DNAseI (Invitrogen) digestion.
Project description:Desiccation tolerance has been implicated as an important characteristic that potentiates the spread of the bacterial pathogen Acinetobacter baumannii through hospitals on dry surfaces. Despite the potential importance of this stress response, scarce information is available describing the underlying mechanisms of A. baumannii desiccation tolerance. Here we characterize the factors influencing desiccation survival of A. baumannii. At the macroscale level, we find that desiccation tolerance is influenced by cell density, growth phase, and desiccation medium. Our transcriptome analysis indicates that desiccation represents a unique state for A. baumannii compared to commonly studied growth conditions and strongly influences pathways responsible for proteostasis. Remarkably, we find that an increase in total cellular protein aggregates, which is often considered deleterious, correlates positively with the ability of A. baumannii to survive desiccation. We show that artificially inducing protein aggregate formation increases desiccation survival, and more importantly, that proteins incorporated into cellular aggregates can retain activity. Our results suggest that protein aggregates may promote desiccation tolerance in A. baumannii through preserving and protecting proteins from damage during desiccation until rehydration occurs.
Project description:The trancriptomic changes in Acinetobacter baumannii after Sono-Fenton inactivation was reported. A total of 148 genes were significantly expressed after the treatment. The genes involved in stress related response were up-regulated while the genes responsible for vital cell functioning were down-regulated.
Project description:A. baumannii has the propensity to colonize abiotic surfaces and this is thought to mediate its transmission to susceptible patients. We found that disruption of A. baumannii ribonuclease T2 family protein (ATCC 17978 locus A1S_3026) severely diminishes the organism's ability to colonize abiotic surfaces. We used Affymetrix A. baumannii GeneChips (part number PMDACBA1) to compare the gene expression properties of wild type and isogenic ribonuclease T2 family protein mutant cells.
Project description:In A. baumannii, adequate zinc acquisition is required for the bacterium to express its full virulence potential. In excess, zinc can also induce significant cellular toxicity. The impact of zinc toxicity on biological systems has primarily been linked to its ability to bind non-zinc metalloproteins. The consequences of zinc intoxication include enhanced oxidative stress susceptibility and alteration of carbon source utilisation.
Project description:The long-term resistance to desiccation on abiotic surfaces is a key determinant of the adaptive success of Acinetobacter baumannii as a healthcare-associated bacterial pathogen. Here, the cellular and molecular mechanisms enabling A. baumannii to resist desiccation and persist on abiotic surfaces were investigated. Experiments were set up to mimic the A. baumannii response to air-drying that would occur when bacterial cells contaminate fomites in hospitals. Resistance to desiccation and transition to the “viable but nonculturable” (VBNC) state were determined in the laboratory-adapted strain ATCC 19606T and the epidemic strain ACICU. Culturability, membrane integrity, metabolic activity, virulence, and gene expression profile were compared between the two strains at different stages of desiccation. Upon desiccation, ATCC 19606T and ACICU cells lose culturability and membrane integrity, lower their metabolism, and enter the VBNC state. However, desiccated A. baumannii cells fully recover culturability and virulence in an insect infection model following rehydration in physiological buffers or human biological fluids. Transcriptome and chemical analyses of A. baumannii cells during desiccation unveiled the production of protective metabolites (L-cysteine and L-glutamate) and decreased energetic metabolism consequent to activation of the glyoxylate shunt (GS) pathway, as confirmed by reduced resuscitation efficiency of aceA mutants, lacking the key enzyme of the GS pathway. VBNC cell formation and extensive metabolic reprogramming provide a biological basis for the response of A. baumannii to desiccation, with implications on environmental control measures aimed at preventing the transmission of A. baumannii infection in hospitals.