Solvent stress response of the denitrifying bacterium "Aromatoleum aromaticum" strain EbN1.
The denitrifying betaproteobacterium "Aromatoleum aromaticum" strain EbN1 degrades several aromatic compounds, including ethylbenzene, toluene, p-cresol, and phenol, under anoxic conditions. The hydrophobicity of these aromatic solvents determines their toxic properties. Here, we investigated the response of strain EbN1 to aromatic substrates at semi-inhibitory (about 50% growth inhibition) concentrations under two different conditions: first, during anaerobic growth with ethylbenzene (0.32 mM) or toluene (0.74 mM); and second, when anaerobic succinate-utilizing cultures were shocked with ethylbenzene (0.5 mM), toluene (1.2 mM), p-cresol (3.0 mM), and phenol (6.5 mM) as single stressors or as a mixture (total solvent concentration, 2.7 mM). Under all tested conditions impaired growth was paralleled by decelerated nitrate-nitrite consumption. Additionally, alkylbenzene-utilizing cultures accumulated poly(3-hydroxybutyrate) (PHB) up to 10% of the cell dry weight. These physiological responses were also reflected on the proteomic level (as determined by two-dimensional difference gel electrophoresis), e.g., up-regulation of PHB granule-associated phasins, cytochrome cd(1) nitrite reductase of denitrification, and several proteins involved in oxidative (e.g., SodB) and general (e.g., ClpB) stress responses.
Trautwein
Kathleen
K
Institute of Chemistry and Biology of the Marine Environment (ICBM), University of Oldenburg, Carl-von-Ossietzky Str. 9-11, D-26111 Oldenburg, Germany. rabus@icbm.de
Kühner
Simon
S
Wöhlbrand
Lars
L
Halder
Thomas
T
Kuchta
Kenny
K
Steinbüchel
Alexander
A
Rabus
Ralf
R
D000693:Anaerobiosis; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000096:biosynthesis; D020562:Betaproteobacteria / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development / Q000502:physiology*; D015180:Electrophoresis, Gel, Two-Dimensional; D015964:Gene Expression Regulation, Bacterial; D006841:Hydrocarbons, Aromatic / Q000494:pharmacology*; D006885:Hydroxybutyrates / Q000378:metabolism; D013058:Mass Spectrometry; D009566:Nitrates / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D011091:Polyesters / Q000378:metabolism; D020543:Proteome / Q000032:analysis; D012997:Solvents / Q000494:pharmacology*; D000094122:Polyhydroxybutyrates
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D006841:Hydrocarbons, Aromatic; D006885:Hydroxybutyrates; D009566:Nitrates; D009573:Nitrites; D011091:Polyesters; D020543:Proteome; D012997:Solvents; C003182:poly-beta-hydroxybutyrate; D000094122:Polyhydroxybutyrates