https://nova.newcastle.edu.au/vital/access/ /manager/Index ${session.getAttribute("locale")} 5 https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:51223 Wed 28 Feb 2024 15:37:01 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49443 Wed 28 Feb 2024 14:45:02 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50035 Wed 24 Jan 2024 15:36:26 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:39776 Wed 22 Jun 2022 12:26:08 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50275 Wed 12 Jul 2023 15:07:08 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:14962 Wed 11 Apr 2018 11:33:35 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:39628 Pseudomonas fluorescens group and Brachypodium distachyon, a model for economically important food, feed, forage, and biomass crops of the grass family. We collected and analyzed root exudates of B. distachyon and demonstrated the presence of multiple carbohydrates, amino acids, organic acids, and phenolic compounds. The subsequent screening of bacteria by Biolog Phenotype MicroArrays revealed that many of these metabolites provide carbon and energy for the Pseudomonas strains. RNA-seq profiling of bacterial cultures amended with root exudates revealed changes in the expression of genes encoding numerous catabolic and anabolic enzymes, transporters, transcriptional regulators, stress response, and conserved hypothetical proteins. Almost half of the differentially expressed genes mapped to the variable part of the strains' pangenome, reflecting the importance of the variable gene content in the adaptation of P. fluorescens to the rhizosphere lifestyle. Our results collectively reveal the diversity of cellular pathways and physiological responses underlying the establishment of mutualistic interactions between these beneficial rhizobacteria and their plant hosts.]]> Wed 10 Aug 2022 11:58:55 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:54519 Tue 27 Feb 2024 15:46:23 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:38597 Pseudomonas aeruginosa We show that no single component of honey can account for its total antimicrobial action, and that honey affects the expression of genes in the SOS response, oxidative damage, and quorum sensing. Manuka honey uniquely affects genes involved in the explosive cell lysis process and in maintaining the electron transport chain, causing protons to leak across membranes and collapsing the proton motive force, and it induces membrane depolarization and permeabilization in P. aeruginosa. These data indicate that the activity of manuka honey comes from multiple mechanisms of action that do not engender bacterial resistance. Importance: The threat of antimicrobial resistance to human health has prompted interest in complex, natural products with antimicrobial activity. Honey has been an effective topical wound treatment throughout history, predominantly due to its broad-spectrum antimicrobial activity. Unlike traditional antibiotics, honey-resistant bacteria have not been reported; however, honey remains underutilized in the clinic in part due to a lack of understanding of its mechanism of action. Here, we demonstrate that honey affects multiple processes in bacteria, and this is not explained by its major antibacterial components. Honey also uniquely affects bacterial membranes, and this can be exploited for combination therapy with antibiotics that are otherwise ineffective on their own. We argue that honey should be included as part of the current array of wound treatments due to its effective antibacterial activity that does not promote resistance in bacteria.]]> Tue 16 Nov 2021 15:46:30 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50476 Tue 14 Nov 2023 15:04:31 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:54509 Tue 12 Mar 2024 17:50:03 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:44763 Pseudomonas is a large and diverse genus of Gammaproteobacteria. To provide a framework for discovery of evolutionary and taxonomic relationships of these bacteria, we compared the genomes of type strains of 163 species and 3 additional subspecies of Pseudomonas, including 118 genomes sequenced herein. A maximum likelihood phylogeny of the 166 type strains based on protein sequences of 100 single-copy orthologous genes revealed thirteen groups of Pseudomonas, composed of two to sixty three species each. Pairwise average nucleotide identities and alignment fractions were calculated for the data set of the 166 type strains and 1224 genomes of Pseudomonas available in public databases. Results revealed that 394 of the 1224 genomes were distinct from any type strain, suggesting that the type strains represent only a fraction of the genomic diversity of the genus. The core genome of Pseudomonas was determined to contain 794 genes conferring primarily housekeeping functions. The results of this study provide a phylogenetic framework for future studies aiming to resolve the classification and phylogenetic relationships, identify new gene functions and phenotypes, and explore the ecological and metabolic potential of the Pseudomonas spp.]]> Tue 08 Nov 2022 11:16:28 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:43839 Tue 04 Oct 2022 11:46:39 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:35003 Tue 03 Sep 2019 17:52:20 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50529 Thu 27 Jul 2023 16:05:46 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:37182 Acinetobacter baumannii has rapidly emerged as a major cause of gram-negative hospital infections worldwide. A. baumannii encodes for the transport protein AceI, which confers resistance to chlorhexidine, a widely used antiseptic. AceI is also the prototype for the recently discovered proteobacterial antimicrobial compound efflux (PACE) family of transport proteins that confer resistance to a range of antibiotics and antiseptics in many gram-negative bacteria, including pathogens. The gene encoding AceI is conserved in the core genome of A. baumannii, suggesting that it has an important primordial function. This is incongruous with the sole characterized substrate of AceI, chlorhexidine, an entirely synthetic biocide produced only during the last century. Here we investigated a potential primordial function of AceI and other members of the PACE family in the transport of naturally occurring polyamines. Polyamines are abundant in living cells, where they have physiologically important functions and play multifaceted roles in bacterial infection. Gene expression studies revealed that the aceI gene is induced in A. baumannii by the short-chain diamines cadaverine and putrescine. Membrane transport experiments conducted in whole cells of A. baumannii and Escherichia coli and also in proteoliposomes showed that AceI mediates the efflux of these short-chain diamines when energized by an electrochemical gradient. Assays conducted using 8 additional diverse PACE family proteins identified 3 that also catalyze cadaverine transport. Taken together, these results demonstrate that short-chain diamines are common substrates for the PACE family of transport proteins, adding to their broad significance as a novel family of efflux pumps.]]> Thu 27 Aug 2020 12:47:49 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49090 Thu 04 May 2023 14:03:55 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:40641 Mon 30 Oct 2023 09:40:36 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:40912 Mon 25 Jul 2022 12:09:49 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:44159 Acinetobacter baumannii is a ubiquitous Gram-negative bacterium, that is associated with significant disease in immunocompromised individuals. The success of A. baumannii is partly attributable to its high level of antibiotic resistance. Further, A. baumannii expresses a broad arsenal of putative zinc efflux systems that are likely to aid environmental persistence and host colonization, but detailed insights into how the bacterium deals with toxic concentrations of zinc are lacking. In this study we present the transcriptomic responses of A. baumannii to toxic zinc concentrations. Subsequent mutant analyses revealed a primary role for the resistance-nodulation-cell division heavy metal efflux system CzcCBA, and the cation diffusion facilitator transporter CzcD in zinc resistance. To examine the role of zinc at the host-pathogen interface we utilized a murine model of zinc deficiency and challenge with wild-type and czcA mutant strains, which identified highly site-specific roles for zinc during A. baumannii infection. Overall, we provide novel insight into the key zinc resistance mechanisms of A. baumannii and outline the role these systems play in enabling the bacterium to survive in diverse environments.]]> Mon 10 Oct 2022 09:45:29 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:47900 Mon 06 Feb 2023 14:13:54 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:37942 Acinetobacter baumannii. Our analyses reveal that AA and DHA incorporate into the A. baumannii bacterial membrane and impact bacterial fitness and membrane integrity, with DHA having a more pronounced effect. Through transcriptional profiling and mutant analyses, we show that the A. baumannii β-oxidation pathway plays a protective role against AA and DHA, by limiting their incorporation into the phospholipids of the bacterial membrane. Furthermore, our study identified a second bacterial membrane protection system mediated by the AdeIJK efflux system, which modulates the lipid content of the membrane via direct efflux of lipids other than AA and DHA, thereby providing a novel function for this major efflux system in A. baumannii This is the first study to examine the antimicrobial effects of host fatty acids on A. baumannii and highlights the potential of AA and DHA to protect against A. baumannii infections.Importance: A shift in the Western diet since the industrial revolution has resulted in a dramatic increase in the consumption of omega-6 fatty acids, with a concurrent decrease in the consumption of omega-3 fatty acids. This decrease in omega-3 fatty acid consumption has been associated with significant disease burden, including increased susceptibility to infectious diseases. Here we provide evidence that DHA, an omega-3 fatty acid, has superior antimicrobial effects upon the highly drug-resistant pathogen Acinetobacter baumannii, thereby providing insights into one of the potential health benefits of omega-3 fatty acids. The identification and characterization of two novel bacterial membrane protective mechanisms against host fatty acids provide important insights into A. baumannii adaptation during disease. Furthermore, we describe a novel role for the major multidrug efflux system AdeIJK in A. baumannii membrane maintenance and lipid transport. This core function, beyond drug efflux, increases the appeal of AdeIJK as a therapeutic target.]]> Mon 05 Jul 2021 16:17:04 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:53066 Fri 17 Nov 2023 11:52:33 AEDT ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49376 Fri 12 May 2023 14:13:07 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:49356 Fri 12 May 2023 12:28:00 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:50201 Fri 07 Jul 2023 09:49:40 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:42774 Fri 02 Sep 2022 11:00:23 AEST ]]> https://nova.newcastle.edu.au/vital/access/ /manager/Repository/uon:34759 Acinetobacter baumannii has emerged as one of the leading causative agents of nosocomial infections. Due to its high level of intrinsic and adapted antibiotic resistance, treatment failure rates are high, which allows this opportunistic pathogen to thrive during infection in immune-compromised patients. A. baumannii can cause infections within a broad range of host niches, with pneumonia and bacteraemia being associated with the greatest levels of morbidity and mortality. Although its resistance to antibiotics is widely studied, our understanding of the mechanisms required for dealing with environmental stresses related to virulence and hospital persistence, such as copper toxicity, is limited. Here, we performed an in silico analysis of the A. baumannii copper resistome, examining its regulation under copper stress. Using comparative analyses of bacterial P-type ATPases, we propose that A. baumannii encodes a member of a novel subgroup of P1B-1 ATPases. Analyses of three putative inner membrane copper efflux systems identified the P1B-1 ATPase CopA as the primary mediator of cytoplasmic copper resistance in A. baumannii. Using a murine model of A. baumannii pneumonia, we reveal that CopA contributes to the virulence of A. baumannii. Collectively, this study advances our understanding of how A. baumannii deals with environmental copper toxicity, and it provides novel insights into how A. baumannii combats adversities encountered as part of the host immune defence.]]> Fri 01 Apr 2022 09:29:40 AEDT ]]>