Studies

Effect of benzoate treatment (high concentrations) on ATP levels and Pdr12 expression after pretreatment of cells with low concentrations of benzoic acid.

Cell survival was determined under different benzoic acid concentrations

Mathematical modelling of the dynamic shift experiments and the effect of pH upon gene regulation.

B. subtilis was grown in minimal media in a chemostat at different growth rates (µ= max, µ=0.1, µ=0.4) and in the presence of 1.2M NaCl (µ=0.1) with or without glycinebetaine. Transcriptome, proteome and metabolome were investigated.

Here we develop a set of new tools for S. pneumoniae and as a case study we show that S. pneumoniaea SMC is recruited to oriC by ParB and promotes chromosome segregation.

Goals:

1. Understanding the regulatory principles of Escherichia coli’s electron transport chain (ETC) for varying oxygen conditions in glucose-limited continuous cultures (especially regulatory loops via the transcription factors FNR and ArcA).
2. Explaining the observed phenomena in the measurement data.
3. Predicting unmeasured variables especially of the gene expression regulatory loops.

Means:

1. Experiments (chemostat experiments within the aerobiosis scale).
2. Kinetic modelling (especially ...

Selected strains from the collection of GFP-tagged S. cerevisiae strains are cultivated at different extracellular caion concentrations and the localization of the GFP-tagged protein will be studied by confocal microscopy. The effect of deletion of the BMH1 gene, encoding the major 14-3-3 isoform, will be analyzed.

3 chemostat experiments:

each in 4 biological replicates incl. 1 fed with labelled glucose T = 37°C pH = 7.1 V_R = 300 mL (dasgip parallel bioreactor system) V_G = 9 sL/h (0.5 vvm) M9 Minimal medium + 3,4-dihydroxybenzoate (chelating agent) + 1g/L Glucose n = 1000 rpm

3 conditions:

"reference" without additional sodium chloride as control "stress" supplemented with 1.2M sodium chloride "osmoprotection" supplemented with 1.2M sodium chloride and 1mM glycine betaine (osmoprotectant)

Provided with genomic data over different pH values we have the opportunity to study the similarity of gene expression profiles and cluster groups of very simlar gene expression profiles. Via PCA we can furthermore study dynamic similarity and compe genes that are possible co-regulators or anti-regulators in the clostridial metabolism.

The main aim of this experiment is to actively grow B.subtilis in presense of glucose until high optical density in an aerobic fermentor and then, at a definite point of the growth, the glucose supply is shut down which leads to complete glucose exhaustion in the media. Simultaneusly samples for transcriptomics, intra and extracellular metabolomics, intra and extracellular proteomics are harvested through out the experiment.

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Experiments using shake flask cultures to measure dynamics associated with sigB response.

To model the ENA1 transcriptional regulation a model has to be established. First this will be just a graphical representation, it shall then be extended to a boolean model and shall at one point be converted to a kinetic model.

Mutant strains which carry deletions of important metabolic enzymes, as well as mutant strains with altered regulation, need to adapt by changing fluxes or gene expression to compensate with the absence/differed concentration of these key enzymes. This may give new insights in the regulation of these pathways/enzymes.

The pilot experiment has been set up in order to develop uniform SOPs for the Sulfosys consortium. It comprises proteomics, transcriptomics, metabolomics as well as enzymatic essays. Cells for all the members of the consortium have been obtained from the same batch fermentations according to fermentation SOP of Sulfosys. The pilot resulted in creating a procedures for all the techniques used in consortium.

Cells are starved. Potassium and subsequently glucose are added to the medium. Proton and potassium fluxes across the plasma membrane are recorded before and after these events for WT and mutants lacking specific transporter proteins.

In this kind of studies sigmaB stress response is induced by the addition of artificial inducers of sigmaB. For example simgaB is downstream of a Pspac promoter and induced by the addition of IPTG. A ctc::lacZ reporter gene is used to monitor sigmaB activity.

The steady state anaerobic culture (D = 0.1 h-1) was pertrubed by sudden increase of the extracellular glucose up to 1 g/L and both extra- and intracellular transient metabolite concentrations were measured

The aim of the study is to test the interplay of the effects of different transcriptional regulators on gene expression during different environmental responses in B. subtilis. For a selected set of transcriptional regulators native proteins are fusion-labelled. The intensity of expression of each reporter protein is measured in the absence of several transcriptional regulators that compete for the RNA polymerase.

Steady state fluxes in yeast Saccharomyces cerevisiae in anaerobic chemostat at D=0.1 h-1

Steady state concentrations of metabolites in yeast Saccharomyces cerevisiae in anaerobic chemostat at D=0.1 h-1

The main aim of this experiment is to actively grow B.subtilis in presense of glucose until high optical density in an aerobic fermentor and then, at a definite point of the growth, the glucose supply is shut down which leads to complete glucose exhaustion in the media. Simultaneusly samples for transcriptomics, intra and extracellular metabolomics, intra and extracellular proteomics are harvested through out the experiment.

Growth of B.subtilis in shakeflask at 57°C; 16°C, 37°C(Control) and 1,2M NaCl in SMM.

BMM EtOH, 16, 57 SMM NaCl