Article Abstract:
The membrane cells of Pseudomonas putida S12 react to various environmental stress differently, showing varying trans/cis ratios of unsaturated fatty acids. An increase in the ratio of trans to cis characterizes the cell's reaction to the addition of heavy metals. Exposure at 30 degrees C results in optimal growth of cells, while gradual reduction in temperature decreases the saturation rate of fatty acids. Toxic concentrations of sodium chloride or sucrose increases the trans/cis ratio. Exposure to pH between 4.0 and 5.0 shows optimum cis/trans isomerase activity with a loss of viability.
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Article Abstract:
Expression of the TOL plasmid may render Pseudomonas putida incapable of growth on benzoate or m-toluate plates, despite having grown in continuous culture on benzoate or m-toluate. After growth in carbon-limited continuous culture, bacteria may have to adapt to the carbon source in solid media and to the increases in potentially inhibitory substrates and intermediates. TOL plasmids may hinder this adaptation. This phenomenon may result in underestimation of viable cell numbers using plate counts.
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Article Abstract:
A study was conducted to investigate the cell envelope dynamics of solvent-tolerant organisms. The phospholipid content, lipopolysaccharide structure and permeability of Pseudomonas putida Idaho and Pseudomonas putida MW1200 after exposure to o-Xylene were compared. Results showed that solvent tolerance occurs in the absence of metabolism of the organic solvent. Trans-unsaturated fatty acids were not found to confer solvent tolerance.
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