Project description:High intracellular levels of unbound iron can contribute to the production of reactive oxygen species (ROS) in the Fenton reaction, while depletion of iron limits the availability of iron containing proteins, some of which have important functions in the oxidative stress defense. Vice versa increased ROS levels lead to damage of proteins with iron sulfur centers. Thus organisms have to coordinate and balance their responses to oxidative stress and iron availability. Our knowledge on the molecular mechanisms underlying the coregulation of these responses is still limited. To discriminate between a direct cellular response to iron limitation and indirect responses, which are the consequence of increased levels of ROS, we compared the response of the alpha proteobacterium Rhodobacter sphaeroides to iron limitation in presence or absence of oxygen. While some genes respond to iron limitation exclusively or much stronger in presence of oxygen, other genes show much stronger response in anaerobic conditions. Remarkably few genes show even opposite response to iron depletion in presence or absence of iron. RNA samples collected from anaerobically grown cultures in presence or absence of iron were analyzed by two-color microarrays
Project description:High intracellular levels of unbound iron can contribute to the production of reactive oxygen species (ROS) in the Fenton reaction, while depletion of iron limits the availability of iron containing proteins, some of which have important functions in the oxidative stress defense. Vice versa increased ROS levels lead to damage of proteins with iron sulfur centers. Thus organisms have to coordinate and balance their responses to oxidative stress and iron availability. Our knowledge on the molecular mechanisms underlying the coregulation of these responses is still limited. To discriminate between a direct cellular response to iron limitation and indirect responses, which are the consequence of increased levels of ROS, we compared the response of the alpha proteobacterium Rhodobacter sphaeroides to iron limitation in presence or absence of oxygen. While some genes respond to iron limitation exclusively or much stronger in presence of oxygen, other genes show much stronger response in anaerobic conditions. Remarkably few genes show even opposite response to iron depletion in presence or absence of iron. RNA samples collected from anaerobically or microaerobically grown cultures in presence or absence of iron were analyzed by RNA_sequencing
Project description:The study aimed to identify role of OxyR during growth on different electron acceptors when E. coli are growing anaerobically. Wt and OxyR null cells were grown on nitrate and fumarate medium anaerobically. Each condition was done in duplicate. RNA was extracted using Qiagen RNeasy kit after stabilization of RNA with RNA protect bacteria reagent. Hybridization and further processing was done based on Affymetrix protocols on E. coli Genome 2.0 arrays.
Project description:This SuperSeries is composed of the following subset Series: GSE21312: Gene expression in a Geobacter sulfurreducens strain adapted for faster Fe(III) oxide reduction grown with ferric citrate as an electron acceptor GSE21313: Gene expression in a Geobacter sulfurreducens strain adapted for faster Fe(III) oxide reduction grown with fumarate as an electron acceptor Refer to individual Series
Project description:Geobacter sulfurreducens PCA was put under selective pressure for rapid Fe(III) oxide reduction. The resultant strain, V1, contained five confirmed mutations and reduced Fe(III) oxide 17 times faster. One of these five mutations inactivates dcuB, a fumarate/succinate antiporter necessary for growth with fumarate as an electron acceptor. V1 dcuB+ is a V1 strain containing a wild type copy of dcuB. Whole genome DNA microarray analysis was performed in order to determine which genes are up- or down-regulated in V1 dcuB+ compared to PCA, both grown with fumarate as an electron acceptor. Three biological replicates were hybridized in duplicate. Experimental (V1) was labeled with cy5, control (wild type PCA) was labeled with cy3.
Project description:Geobacter sulfurreducens PCA was put under selective pressure for rapid Fe(III) oxide reduction. The resultant strain, V1, contained five confirmed mutations and reduced Fe(III) oxide 17 times faster. Whole genome DNA microarray analysis was performed in order to determine which genes are up- or down-regulated in V1 compared to PCA, both grown with ferric citrate as an electron acceptor. Three biological replicates were hybridized in duplicate. Experimental (V1) was labeled with cy5, control (wild type PCA) was labeled with cy3.
Project description:To gain a deeper understanding of the transcription factors that regulate photosynthesis in Rhodobacter sphaeroides global gene expression analysis was used to determine the expression profiles of the deletion mutants of 4 transcription factors (FnrL, PrrA, CrpK and RSP_2888) known or predicted to be involved in the regulation of photosynthesis. Microarray analysis conducted for deletion strains of 4 transcription factors known or predicted to be involved in the regulation of photosynthesis in Rhodobacter sphaeroides using the R. sphaeroides Affymetrix gene chip. These deletion mutant expression profiles were compared to that of wild type cells to determine differentially expressed genes regulated by these transcription factors.
Project description:S. oneidensis MR-1 was grown with different electron acceptors: an electrode at 0.4 V vs. SHE, 50 mM Fe(III)citrate, and oxygen. The gene expression pattern for each experiment was analyzed and the differences in gene expression for the different experimental conditions were compared. For two samples S. oneidensis was grown with a graphite anode electrode (at 0.4 V. vs. SHE) as the only electron acceptor - one sample was directly fed with 20 mM lactate, one sample was fed with lactate produced during fermentation of glucose by Lactococcus lactis. Four samples were grown anaerobically with 50 mM Fe(III)citrate as the only electron acceptor, and 20 mM lactate for 20 h. Three samples were grown aerobically with 20 mM lactate for 20 h. The same modified M4 medium was used for all samples. For RNA extraction, the biofilm was scraped off the frozen (-80M-BM-0C) carbon electrode with a sterile razor blade. Biofilm-carbon sludge was combined with 7 mL ice-cold phosphate buffer saline (PBS), vortexed, sonicated at 7 W for 30 s on ice (3 repetitions), and centrifuged. For the liquid cultures, 2 mL of each culture were combined with 2 mL RNA protect, vortexed, and centrifuged at 5,500g for 10 min. The pellets were resuspended in NAES buffer (50 mM sodium acetate buffer, 10 mM EDTA and 1 % SDS at pH 5). RNA was isolated with a phenol:chloroform extraction protocol.
Project description:Investigation of whole genome changes in six serotypes of Actinobacillus pleuropneumoniae in control cultures compared to bacteria grown in media containg the iron chelator 2,2'-dipyridyl. A 48 chip study using total RNA recovered from four different control cultures and four different iron depleted cultures of Actinobacillus pleuropneumoniea serotype 1 (4074), serotype 2 (4226), serotype 3 (1421), serotype 5b(L209, serotype 6 (7712640) and serotype 7 (WF87).
Project description:Desulfuromonas acetexigens is capable of extracellular electron transfer (EET) and can generate high peak current densities >9 A/m2 in a very short period (~20 h after inoculation) under potential induced growth (–0.1 V vs. Ag/AgCl) and acetate as the electron donor. Despite its high electrochemical activity in microbial electrochemical systems, the proteome and EET mechanisms of D. acetexigens are still unknown. Here, the proteome of D. acetexigens was characterized and a stimulus-induced comparative analysis was performed to elucidate its putative EET mechanism. Proteome analysis indicates that D. acetexigens is a versatile bacterium with a high diversity of accessory genes that allow it to adapt to diverse environments.