Project description:In the frame of the European MELiSSA project, which aims to develop a closed biological life support system for forthcoming long term space exploration missions, the study of the alpha-proteobacterium Rhodospirillum rubrum S1H cultivated in space related environmental conditions has started. In the present work, the bacterium was grown using two different microgravity simulators, namely the Rotating Wall Vessel (RWV) and the Random Positioning Machine (RPM) and its response was evaluated at both the transcriptomic and proteomic levels using respectively a dedicated whole-genome microarray and high-througput proteomics. At the transcriptomic level, 13 genes were found significantly induced in the RWV samples and all 13 were included in the more pronounced response of 235 induced genes of R. rubrum S1H to the RPM cultivation. On the other hand, at the proteomic level, a few common proteins were found to be differentially expressed in RWV and RPM while the RWV appeared to induce a higher number of significantly regulated proteins. However, the transcriptomic and the proteomic approaches appeared to be complementary pointing out the likely interrelation between quorum sensing, cell pigmentation and cell aggregation in R. rubrum S1H. Future studies will aim to characterize this unknown quorum sensing regulon.
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: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.