The Nature and Relevance of Solvent Stress in Microbes and Mechanisms of Tolerance

ABSTRACT In Ralstonia pickettii PKO1, a denitrifying toluene oxidizer that carries a toluene-3-monooxygenase (T3MO) pathway, the biodegradation of toluene and trichloroethylene (TCE) by the organism is induced by TCE at high concentrations. In this study, the effect of TCE preexposure was studied in the context of bacterial protective response to TCE-mediated toxicity in this organism. The results of TCE degradation experiments showed that cells induced by TCE at 110 mg/liter were more tolerant to TCE-mediated stress than were those induced by TCE at lower concentrations, indicating an ability of PKO1 to adapt to TCE-mediated stress. To characterize the bacterial protective response to TCE-mediated stress, the effect of TCE itself (solvent stress) was isolated from TCE degradation-dependent stress (toxic intermediate stress) in the subsequent chlorinated ethylene toxicity assays with both nondegradable tetrachloroethylene and degradable TCE. The results of the toxicity assays showed that TCE preexposure led to an increase in tolerance to TCE degradation-dependent stress rather than to solvent stress. The possibility that such tolerance was selected by TCE degradation-dependent stress during TCE preexposure was ruled out because a similar extent of tolerance was observed in cells that were induced by toluene, whose metabolism does not produce any toxic products. These findings suggest that the adaptation of TCE-induced cells to TCE degradation-dependent stress was caused by the combined effects of solvent stress response and T3MO pathway expression.

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The thermal properties and solvent stress cracking resistance of some new polyethers

Thermochimica Acta ◽

10.1016/0040-6031(80)80038-4 ◽

1980 ◽

Vol 37 (2) ◽

pp. 173-178 ◽

Cited By ~ 2

Author(s):

Georgius A. Adam ◽

N.A. Husein ◽

Mohmood M. Barbooti

Keyword(s):

Thermal Properties ◽

Cracking Resistance ◽

Stress Cracking ◽

Solvent Stress

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Aromatic Acid Metabolites of Escherichia coli K-12 Can Induce the marRAB Operon

Journal of Bacteriology ◽

10.1128/jb.00371-10 ◽

2010 ◽

Vol 192 (18) ◽

pp. 4786-4789 ◽

Cited By ~ 29

Author(s):

Lon M. Chubiz ◽

Christopher V. Rao

Keyword(s):

Escherichia Coli ◽

Antibiotic Resistance ◽

Stress Tolerance ◽

Aromatic Acid ◽

Tryptophan Biosynthesis ◽

Metabolic Intermediates ◽

Acid Metabolites ◽

K 12 ◽

Solvent Stress

ABSTRACT MarR is a key regulator of the marRAB operon involved in antibiotic resistance and solvent stress tolerance in Escherichia coli. We show that two metabolic intermediates, 2,3-dihydroxybenzoate and anthranilate, involved in enterobactin and tryptophan biosynthesis, respectively, can activate marRAB transcription. We also found that a third intermediate involved in ubiquinone biosynthesis, 4-hydroxybenzoate, activates marRAB transcription in the absence of TolC. Of the three, however, only 2,3-dihydroxybenzoate directly binds MarR and affects its activity.

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