Project description:Gluconacetobacter diazotrophicus has been the focus of several studies aiming to understand the mechanisms behind this endophytic diazotrophic bacterium. The present study is the first global analysis of the early transcriptional response of exponentially growing G. diazotrophicus to iron, an essential cofactor for many enzymes involved in various metabolic pathways. RNA-seq, targeted gene mutagenesis and computational motif discovery tools were used to define the G. diazotrophicus Fur regulon. The data analysis showed that genes encoding functions related to iron homeostasis, were significantly upregulated in response to iron limitation. Certain genes involved in the secondary metabolism were overexpressed under iron-limited conditions. In contrast, it was observed that the expression of genes involved in Fe-S cluster biosynthesis, flagellar biosynthesis and type IV secretion systems were downregulated in an iron-depleted culture medium. Our results support a model that control transcription in G. diazotrophicus by Fur function. The G. diazotrophicus Fur protein was able to complement an E. coli fur mutant. These results provide new insights into the effects of iron on the metabolism of G. diazotrophicus, as well as demonstrating the essentiality of this micronutrient for the main characteristic of plant growth promotion by G. diazotrophicus.
Project description:The sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough possesses four periplasmic hydrogenases to facilitate the oxidation of molecular hydrogen. These include an [Fe], a [NiFeSe] and two [NiFe] hydrogenases encoded by the hyd, hys, hyn1 and hyn2 genes, respectively. In order to understand their cellular functions the expression levels of these hydrogenases, along with the growth rate analysis of mutant strains, was determined during growth on defined media under 3 different conditions. These conditions incuded lactate or hydrogen at either 5% or 50% (vol/vol) used as the sole electron donor for sulfate reduction. Keywords: Electron donor change
Project description:The sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough possesses four periplasmic hydrogenases to facilitate the oxidation of molecular hydrogen. These include an [Fe], a [NiFeSe] and two [NiFe] hydrogenases encoded by the hyd, hys, hyn1 and hyn2 genes, respectively. In order to understand their cellular functions the expression levels of these hydrogenases, along with the growth rate analysis of mutant strains, was determined during growth on defined media under 3 different conditions. These conditions incuded lactate or hydrogen at either 5% or 50% (vol/vol) used as the sole electron donor for sulfate reduction. Keywords: Electron donor change For each condition 2 unique biological samples were hybridized to 4 arrays that each contained duplicate spots. Genomic DNA was used as universal reference. After total intensity normalization the SAM (significance analysis of microarrays) was used to find differentially expressed genes.
Project description:Sulfur metabolism in the deep-sea cold seep has been mentioned to have an important contribution to the biogeochemical cycle of sulfur in previous studies. And sulfate reducing bacteria have also been considered to be a dominant microbial population in the deep-sea cold seep and play a crucial role in this process. However, most of sulfate reducing bacteria from cold seep still cannot be purely cultured under laboratory conditions, therefore the actual sulfur metabolism pathways in sulfate reducing bacteria from the deep-sea cold seep have remained unclear. Here, we isolate and pure culture a typical sulfate reducing bacterium Desulfovibrio marinus CS1 from the sediment sample of the deep-sea cold seep in the South China Sea, which provides a probability to understand the sulfur metabolism in the cold seep.
Project description:Sulphur is an essential macronutrient for plant growth and development. Reaching a thorough understanding of the molecular basis for changes in plant metabolism depending on the sulphur-nutritional status at the systems level will advance our basic knowledge and help target future crop improvement. Although the transcriptional responses induced by sulphate starvation have been studied in the past, knowledge of the regulation of sulphur metabolism is still fragmentary. This work focuses on the discovery of candidates for regulatory genes such as transcription factors (TFs) using M-bM-^@M-^Xomics technologies. For this purpose a short term sulphate-starvation / re-supply approach was used. ATH1 microarray studies and metabolite determinations yielded 21 TFs which responded more than 2-fold at the transcriptional level to sulphate starvation. Categorization by response behaviors under sulphate-starvation / re-supply and other nutrient starvations such as nitrate and phosphate allowed determination of whether the TF genes are specific for or common between distinct mineral nutrient depletions. Extending this co-behavior analysis to the whole transcriptome data set enabled prediction of putative downstream genes. Additionally, combinations of transcriptome and metabolome data allowed identification of relationships between TFs and downstream responses, namely, expression changes in biosynthetic genes and subsequent metabolic responses. Effect chains on glucosinolate and polyamine biosynthesis are discussed in detail. The knowledge gained from this study provides a blueprint for an integrated analysis of transcriptomics and metabolomics and application for the identification of uncharacterized genes. Arabidopsis seedlings were grown in 30 mL of sterile liquid full nutrition (FN) medium (3 mM sulphate) or 150 M-NM-<M sulphate medium. Transferring pre-grown 7-days old seedlings to a sulphate depleted medium (0 M-NM-<M sulphate) assured immediate and continued sulphate starvation during the next two days of plant cultivation. On day 9 subsets of the sulphate depleted cultures were supplied with sulphate (500 M-NM-<M) and samples taken 30 min and 3 hours after re-supply. Four time points (full nutrition (FN), plants starved for 48 h (-S), plants re-supplied with sulphate for 30 minutes (30M-bM-^@M-^Y S) and plants re-supplied with sulphate for 3 hours (3 h S)) were subjected to the microarray analysis. Two biological repetitions of each sample were analyzed.