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Survival and growth in the presence of elevated copper: transcriptional profiling of copper-stressed Pseudomonas aeruginosa.

ABSTRACT: Transcriptional profiles of Pseudomonas aeruginosa exposed to two separate copper stress conditions were determined. Actively growing bacteria subjected to a pulse of elevated copper for a short period of time was defined as a "copper-shocked" culture. Conversely, copper-adapted populations were defined as cells actively growing in the presence of elevated copper. Expression of 405 genes changed in the copper-shocked culture, compared to 331 genes for the copper-adapted cultures. Not surprisingly, there were genes identified in common to both conditions. For example, both stress conditions resulted in up-regulation of genes encoding several active transport functions. However, there were some interesting differences between the two types of stress. Only copper-adapted cells significantly altered expression of passive transport functions, down-regulating expression of several porins belonging to the OprD family. Copper shock produced expression profiles suggestive of an oxidative stress response, probably due to the participation of copper in Fenton-like chemistry. Copper-adapted populations did not show such a response. Transcriptional profiles also indicated that iron acquisition is fine-tuned in the presence of copper. Several genes induced under iron-limiting conditions, such as the siderophore pyoverdine, were up-regulated in copper-adapted populations. Interesting exceptions were the genes involved in the production of the siderophore pyochelin, which were down-regulated. Analysis of the copper sensitivity of select mutant strains confirmed the array data. These studies suggest that two resistance nodulation division efflux systems, a P-type ATPase, and a two-component regulator were particularly important for copper tolerance in P. aeruginosa.

SUBMITTER: Teitzel GM

PROVIDER: S-EPMC1636237 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature

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Survival and growth in the presence of elevated copper: transcriptional profiling of copper-stressed Pseudomonas aeruginosa.

Teitzel Gail M GM Geddie Ashley A De Long Susan K SK Kirisits Mary Jo MJ Whiteley Marvin M Parsek Matthew R MR

Journal of bacteriology 20061001 20

Transcriptional profiles of Pseudomonas aeruginosa exposed to two separate copper stress conditions were determined. Actively growing bacteria subjected to a pulse of elevated copper for a short period of time was defined as a "copper-shocked" culture. Conversely, copper-adapted populations were defined as cells actively growing in the presence of elevated copper. Expression of 405 genes changed in the copper-shocked culture, compared to 331 genes for the copper-adapted cultures. Not surprisingl ...[more]

PMID: 17015663

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Project description:Purpose: The intensive use of metal-based nanoparticles results in their continuous release into the environment and the subsequent destroying microbial biodiversity and causing occurrence of antibiotic resistant determinants. Although previous studies have indicated that nanoparticles may be toxic to microorganisms, there is a scarcity of data available to assess the underlying molecular mechanisms of inhibitory and biocidal effects of nanoparticles on microorganisms, which is a critical gap in our comprehensive understanding of the impacts of nanoparticles on microbial ecosystems. Methods: By combining the global activated/suppressed gene profiles and detected physiological responses, we detected the microbial response to CuO NPs exposure and revealed potential mechanisms of CuO NPs on this prevalent opportunistic pathogen and environmentally relevant denitrifier. Results:Our results indicate that nanoparticles could react directly with the biological membrane, but also change gene expressions. Transmission electron microscopy (TEM) results indicate that CuO nanoparticles not only damaged the structure of the bacterial membrane but also entered the cells. Planktonic cells of P. aeruginosa are energetically compromised after exposure to a sublethal level (1 and 10 mg/L) of CuO nanoparticles. Respiration was likely inhibited as denitrification activity was severely depleted in terms of decreased transcript levels of most denitrification genes. In addition, and of high concern, bacteriophage genes were activated and it is speculated that phage mediated cell lysis. Meanwhile, CuO NP exposure induced significantly up-regulated expressions of metal resistance gene, resistance-nodulation-division, P-type ATPase efflux and cation diffusion facilitator transporters, which can form an integrated network controlling metals concentrations in the cytoplasm and periplasm P. aeruginosa. Conclusion: Based on our results, it is evident that the response of bacteria under the exposure of nanoparticles is very complex, though a clear and comprehensive understanding of the true mechanisms of inhibition or toxicity is still lacking. Our findings will provide insights on whole picture regarding the fundamental mechanisms of microbial susceptibility, tolerance and resistance to exposure of CuO NPs, as well highlight to re-estimate potential risks of CuO NP to public health and environment.

Dataset Information

Survival and growth in the presence of elevated copper: transcriptional profiling of copper-stressed Pseudomonas aeruginosa.

Publications

Survival and growth in the presence of elevated copper: transcriptional profiling of copper-stressed Pseudomonas aeruginosa.

Similar Datasets

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