Project description:In the present study, the susceptibility of the purple pigmented photosynthetic alphaproteobacterium Rhodospirillum rubrum S1H to gamma irradiation was investigated and its molecular response was characterised by means of gene expression analysis. R. rubrum S1H appears to be about 4 times more sensitive than the model strain Escherichia coli MG1655 to cobalt-60 gamma irradiation. Whole genome response of R. rubrum to 25 Gy revealed the common expression of SOS response related genes in both rich and minimal media. Quantitative expression of the lexA gene was followed after various recovery time following gamma irradiation and showed differential gene expression pattern between minimal and rich medium. This work paves the way for forthcoming molecular studies on the effect of ionizing radiation on R. rubrum S1H and the other MELiSSA strains. Keywords: Rhodospirillum rubrum; ionizing radiation tolerance; microarray; quantitative PCR.
Project description:In the present study, the susceptibility of the purple pigmented photosynthetic alphaproteobacterium Rhodospirillum rubrum S1H to gamma irradiation was investigated and its molecular response was characterised by means of gene expression analysis. R. rubrum S1H appears to be about 4 times more sensitive than the model strain Escherichia coli MG1655 to cobalt-60 gamma irradiation. Whole genome response of R. rubrum to 25 Gy revealed the common expression of SOS response related genes in both rich and minimal media. Quantitative expression of the lexA gene was followed after various recovery time following gamma irradiation and showed differential gene expression pattern between minimal and rich medium. This work paves the way for forthcoming molecular studies on the effect of ionizing radiation on R. rubrum S1H and the other MELiSSA strains. Keywords: Rhodospirillum rubrum; ionizing radiation tolerance; microarray; quantitative PCR. Two-condition experiments. Comparing samples after exposure to gamma (Co-60) irradiation with a non-irradiated sample. At least biological duplicates. Each array contains 3 technical replicates.
Project description:This SuperSeries is composed of the following subset Series: GSE14239: MESSAGE 2 space experiment with Rhodospirillum rubrum S1H GSE14241: BASE-A space experiment with Rhodospirillum rubrum S1H Refer to individual Series
Project description:The present study explores the potential of compound-specific gene-upregulation profiles in the ubiquitous purple nonsulfur bacterium Rhodospirillum rubrum S1H as biomarkers for exposure to surface water contaminants, i.e. high production-volume pharmaceuticals. Even though the pharmaceuticals [i.e., acetylsalicylic acid (ASA), diclofenac (DCF), and 17α-ethinylestradiol (EE2)] did not affect the bacterial growth kinetics at environmentally-relevant concentrations (86nM), whole-genome microarray analyses revealed the upregulation of 128, 49, and 47 genes upon exposure to DCF, ASA, and EE2, respectively. A strong overlap (27-48%) was observed between transcriptional responses, but a total of 93 genes were found to be upregulated in a compound-specific manner. Hence, we were able to identify 74 and 15 potential biomarker genes for DCF and ASA, respectively. DCF specifically induced genes involved mainly in stress response, signal transduction, response regulation, the electron transport chain, and transcription, while ASA specifically induced genes predominantly involved in signal transduction, response regulation, and trans-membrane translocation. Moreover, our findings validated triclosan-specific biomarker genes that were identified previously. As only 4 genes were specifically-upregulated for EE2, no representative biomarker profile was identified. This study illustrates that a pollutant-specific molecular response can be generated in R. rubrum S1H, which could become a relevant model-microorganism to screen for the ecological impact of surface water contaminants in situ. KEYWORDS: environmental impact studies, risk assessment, biosensor, wastewater, micropollutant, aspirin
Project description:Aiming at the development of a micropollutant biosensor in the frame of the Micro-Ecological Life Support System Alternative (MELiSSA), a pilot study was initiated to identify triclosan (TCS)-responsive biomarker genes in the MELiSSA carbon-mineralizing microorganism, Rhodospirillum rubrum S1H. TCS is a biocide, commonly found in human excrements and is considered an emerging pollutant in wastewater and the environment. Chronic exposure to MELiSSA-relevant concentrations (≥25 µg L-1) TCS caused a significant extension of the lag phase without affecting the growth rate. Analytical determination gave no indication of TCS biodegradation during the growth experiment and flow cytometric viability analyses revealed that TCS is only slightly toxic to R. rubrum. Through microarray analyses, the genetic mechanisms supporting the reversibility of TCS-induced inhibition were scrutinized. Hence, an extremely TCS-responsive cluster of four small adjacent genes was revealed, with up to 34-fold induction at 25 µg L-1. These four genes, for which the name micropollutant-upregulated factor (muf) was proposed; appear to be unique to R. rubrum and are shown for the first time to be involved in the response to stress. Moreover, numerous other systems that are associated with the proton-motive force were shown to be responsive to TCS, but never as highly upregulated as the muf genes. Hence, R. rubrum induced the phage shock protein operon (pspABC), numerous major facilitator efflux systems, cell envelope consolidation mechanisms, oxidative stress response, beta-oxidation, and carbonic anhydrase; while downregulating bacterial conjugation- and carboxysome synthesis genes. The muf genes and three efflux-related genes showed most potential as low-dose biomarkers. The two microarray experiments (10 and 25 µg l-1 Triclosan) were all performed in biological triplicate and containing three (in-slide) technical repeats. For all conditions, the Triclosan exposed sample (Cy5) was compared with the non-exposed solvent control (Cy3) to identify those genes that were differentially expressed upon Triclosan exposure.
Project description:The present study explores the potential of compound-specific gene-upregulation profiles in the ubiquitous purple nonsulfur bacterium Rhodospirillum rubrum S1H as biomarkers for exposure to surface water contaminants, i.e. high production-volume pharmaceuticals. Even though the pharmaceuticals [i.e., acetylsalicylic acid (ASA), diclofenac (DCF), and 17M-NM-1-ethinylestradiol (EE2)] did not affect the bacterial growth kinetics at environmentally-relevant concentrations (86nM), whole-genome microarray analyses revealed the upregulation of 128, 49, and 47 genes upon exposure to DCF, ASA, and EE2, respectively. A strong overlap (27-48%) was observed between transcriptional responses, but a total of 93 genes were found to be upregulated in a compound-specific manner. Hence, we were able to identify 74 and 15 potential biomarker genes for DCF and ASA, respectively. DCF specifically induced genes involved mainly in stress response, signal transduction, response regulation, the electron transport chain, and transcription, while ASA specifically induced genes predominantly involved in signal transduction, response regulation, and trans-membrane translocation. Moreover, our findings validated triclosan-specific biomarker genes that were identified previously. As only 4 genes were specifically-upregulated for EE2, no representative biomarker profile was identified. This study illustrates that a pollutant-specific molecular response can be generated in R. rubrum S1H, which could become a relevant model-microorganism to screen for the ecological impact of surface water contaminants in situ. KEYWORDS: environmental impact studies, risk assessment, biosensor, wastewater, micropollutant, aspirin Two-condition experiments. Comparing samples after induction of three pharmaceuticals each with a non-induced samples. Biological triplicate. Each array contains 3 technical replicates.
Project description:Aiming at the development of a micropollutant biosensor in the frame of the Micro-Ecological Life Support System Alternative (MELiSSA), a pilot study was initiated to identify triclosan (TCS)-responsive biomarker genes in the MELiSSA carbon-mineralizing microorganism, Rhodospirillum rubrum S1H. TCS is a biocide, commonly found in human excrements and is considered an emerging pollutant in wastewater and the environment. Chronic exposure to MELiSSA-relevant concentrations (≥25 µg L-1) TCS caused a significant extension of the lag phase without affecting the growth rate. Analytical determination gave no indication of TCS biodegradation during the growth experiment and flow cytometric viability analyses revealed that TCS is only slightly toxic to R. rubrum. Through microarray analyses, the genetic mechanisms supporting the reversibility of TCS-induced inhibition were scrutinized. Hence, an extremely TCS-responsive cluster of four small adjacent genes was revealed, with up to 34-fold induction at 25 µg L-1. These four genes, for which the name micropollutant-upregulated factor (muf) was proposed; appear to be unique to R. rubrum and are shown for the first time to be involved in the response to stress. Moreover, numerous other systems that are associated with the proton-motive force were shown to be responsive to TCS, but never as highly upregulated as the muf genes. Hence, R. rubrum induced the phage shock protein operon (pspABC), numerous major facilitator efflux systems, cell envelope consolidation mechanisms, oxidative stress response, beta-oxidation, and carbonic anhydrase; while downregulating bacterial conjugation- and carboxysome synthesis genes. The muf genes and three efflux-related genes showed most potential as low-dose biomarkers.