Towards the Response Threshold for -Hydroxyacetophenone in the Denitrifying Bacterium "Aromatoleum aromaticum" EbN1.

The denitrifying betaproteobacterium "" EbN1 regulates the capacity to anaerobically degrade -ethylphenol (via -hydroxyacetophenone) with high substrate specificity. This process is mediated by the σ-dependent transcriptional regulator EtpR, which apparently recognizes both aromatic compounds, yielding congruent expression profiles. The responsiveness of this regulatory system was studied with -hydroxyacetophenone, which is more easily administered to cultures and traced analytically.

Non-Redfield, nutrient synergy and flexible internal elemental stoichiometry in a marine bacterium.

The stoichiometric constraints of algal growth are well understood, whereas there is less knowledge for heterotrophic bacterioplankton. Growth of the marine bacterium Phaeobacter inhibens DSM 17395, belonging to the globally distributed Roseobacter group, was studied across a wide concentration range of NH4+ and PO43-. The unique dataset covers 415 different concentration pairs, corresponding to 207 different molar N:P ratios (from 10-2 to 105).

The predicted σ(54)-dependent regulator EtpR is essential for expression of genes for anaerobic p-ethylphenol and p-hydroxyacetophenone degradation in "Aromatoleum aromaticum" EbN1.

Background: The denitrifying betaproteobacterium "Aromatoleum aromaticum" EbN1 anaerobically utilizes a multitude of aromatic compounds via specific peripheral degradation routes. Compound-specific formation of these catabolic modules is assumed to be mediated by specific transcriptional activators. In case of the recently elucidated p-ethylphenol/p-hydroxyacetophenone pathway, the highly substrate-specific regulation was implicated to involve the predicted σ(54)-dependent, NtrC-type regulator EbA324.