Project description:The gene expression profile of E. coli K-12 MG1655 grown in minimal medium treated with 0.12 mg/L of the biocide triclosan has been analysed using whole genome oligonucleotide microarrays. "Control" RNA was isolated from three independently grown 50ml MOPS minimal media cultures of E. coli K-12 MG1655. “Test” RNA was isolated from three independently grown 50ml MOPS minimal cultures of E. coli K-12 MG1655, to which was added 0.12 mg/L of triclosan after reaching mid-logarithmic growth phase (OD600 ~ 0.7 +/- 0.02). Keywords: dose response
Project description:The gene expression profile of E. coli K-12 MG1655 grown in minimal medium treated with 0.12 mg/L of the biocide triclosan has been analysed using whole genome oligonucleotide microarrays. "Control" RNA was isolated from three independently grown 50ml MOPS minimal media cultures of E. coli K-12 MG1655. âTestâ RNA was isolated from three independently grown 50ml MOPS minimal cultures of E. coli K-12 MG1655, to which was added 0.12 mg/L of triclosan after reaching mid-logarithmic growth phase (OD600 ~ 0.7 +/- 0.02). Keywords: dose response Cy5-labelled cDNA probes were synthesised from three independent biological extractions of RNA from E. coli MG1655 unexposed to triclosan. Cy3-labelled cDNA probes were synthesised from three independent biological extractions of RNA from E. coli MG1655 exposed to 0.12 mg/L of triclosan. A dye-swap control was also included, whereupon the control cDNA probes were labelled with Cy3 and the test cDNA probes labelled with Cy5. Probes were mixed to allow comparison of the control and test expression profiles and hybridised onto an E. coli spotted oligonucleotide array.
Project description:Transcriptional profiling of NTG-treated E. coli imp fabI(G93V) cells compared to control cells (E. coli imp fabI(G93V) ) in the absence or presence of sub-lethal concentration of triclosan.
Project description:We compared the exposure of E. coli MG1655 to ten commonly used antiseptics and disinfectants for short (30min) and long (7-12h) term, looking for common and unique stress response elements.
Project description:The present work was devoted to a multi-level characterization of E. coli exposed to Ag+-mediated stress using for the first time an approach of integrative biology, based on the combination of physiological, biochemical and transcriptomic data sets. Bacterial growth and survival after Ag+ exposure were first quantified and related to the accumulation of intracellular silver, as detected by Nano Secondary Ion Mass Spectroscopy (NanoSIMS) at high lateral resolution. The whole transcriptomic response of E. coli cells under ionic silver-mediated stress was then characterized. Clear correlations were established between (i) cell physiology, (ii) variations in the biochemical characteristics of cell fatty acids and proteins, and (iii) regulation of gene expression. This challenging approach allowed determining key genetic markers of the E. coli response to ionic silver. In particular, we identified Ag+-mediated regulations of gene expression in correlation with growth (e.g. genes of transporters, transcriptional regulators, ribosomal proteins), necessary for ionic silver transport and detoxification (e.g. copA, cueO, mgtA, nhaR) and to cope with various stress (dnaK, pspA, metA,R, oxidoreductase genes). Regulation of gene expression after Ag+ exposure was also correlated to macromolecular modifications, such as acyl chain length (e.g. fadL, lpxA, arnA), protein secondary structure (e.g. dnaJ, htpX, degP) and cell morphology (e.g. ycfS, ycbB).
Project description:The earliest stages of bacterial adaptation to antibiotics are critical for survival, as the responses initiated in these moments shape the path toward tolerance and resistance. While long-term adaptations have been extensively studied, much less is known about the immediate, complex transcriptional changes that unfold in the first moments after antibiotic exposure. Here, we applied iModulon analysis to time-resolved transcriptomic data from Escherichia coli exposed to subinhibitory concentrations of two antibiotics, capturing regulatory changes within the first 30 minutes of exposure. This analysis reveals an integrated, three-phase framework of adaptation: an immediate and sustained primary response that broadly activates stress programs, a transient secondary response that restores redox balance, and a tertiary response that supports long-term survival through metabolic remodeling and antibiotic-specific defenses. This model provides new insight into how metabolic, redox, and stress responses are integrated to manage the physiological challenges of antibiotic stress, revealing a highly coordinated and dynamic regulatory strategy. By disentangling these overlapping transcriptional programs, our work offers a systems-level understanding of early bacterial adaptation and highlights new opportunities to investigate how survival mechanisms unfold during the critical moments following antibiotic exposure.
Project description:Since the molecular mechanisms behind adaptation and the bacterial stress response toward antimicrobial photodynamic therapy (aPDT) are not entirely clear yet, the aim of the present study was to investigate the transcriptomic stress response in Escherichia coli after sublethal treatment with aPDT using RNA sequencing (RNA-Seq). Planktonic cultures of stationary phase E. coli were treated with aPDT using a sublethal dose of the photosensitizer SAPYR. After treatment, RNA was extracted, and RNA-Seq was performed on the Illumina NextSeq 500. Differentially expressed genes were analyzed and validated by qRT-PCR. The analysis of the differential gene expression following pathway enrichment analysis revealed a considerable number of genes and pathways significantly up- or down-regulated in E. coli after sublethal treatment with aPDT. Expression of 1018 genes was up-regulated and of 648 genes was down-regulated after sublethal treatment with aPDT as compared to irradiated controls. Analysis of differentially expressed genes and significantly de-regulated pathways showed regulation of genes involved in oxidative stress response and bacterial membrane damage. In conclusion, the results show a transcriptomic stress response in E. coli upon exposure to aPDT using SAPYR and give an insight into potential molecular mechanisms that may result in development of adaptation
Project description:Characterization of biological and chemical responses to ionizing radiation by various organisms is essential for potential applications in bioremediation, alternative modes of detecting nuclear material, and national security. Escherichia coli DH10β is an optimal system to study the microbial response to low-dose ionizing radiation at the transcriptional level because it is a well-characterized model bacterium and its responses to other environmental stressors, including those to higher radiation doses, have been elucidated in prior studies. In this study, RNA sequencing with downstream transcriptomic analysis (RNA-seq) was employed to characterize the global transcriptional response of stationary-phase E. coli subjected to Pu-239, H-3 (tritium), and Fe-55, at an approximate absorbed dose rate of 10 mGy day-1 for 1 day and 15 days. Differential expression analysis identified significant changes in gene expression of E. coli for both short- and long-term exposures. Radionuclide source exposure induced differential expression in E. coli of genes involved in biosynthesis pathways of nuclear envelope components, amino acids, and siderophores, transport systems such as ABC transporters and type II secretion proteins, and initiation of stress response and regulatory systems of temperature stress, the RpoS regulon, and oxidative stress. These findings provide a basic understanding of the relationship between low-dose exposure and biological effect of a model bacterium that is critical for applications in alternative nuclear material detection and bioremediation. IMPORTANCE Escherichia coli strain DH10β, a well-characterized model bacterium, was subjected to short-term (1-day) and long-term (15-day) exposures to three different in situ radiation sources comprised of radionuclides relevant to nuclear activities to induce a measurable and identifiable genetic response. We found E. coli had both common and unique responses to the three exposures studied, suggesting both dose rate- and radionuclide-specific effects. This study is the first to provide insights into the transcriptional response of a microorganism in short- and long-term exposure to continuous low-dose ionizing radiation with multiple in situ radionuclide sources and the first to examine microbial transcriptional response in stationary phase. Moreover, this work provides a basis for the development of biosensors and informing more robust dose-response relationships to support ecological risk assessment.
Project description:The purpose of this study is to determine whether the presence of pathogenic Escherichia coli in colon is associated with psychiatric disorders.