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Microbial growth modification by compressed gases and hydrostatic pressure.
1Department of Microbiology, University of Rochester, Rochester, New York 14642.
Applied and Environmental Microbiology
|April 1, 1984
Summary
Two classes of gases affect microbial growth. Class 1 gases (helium, nitrogen, argon) do not inhibit growth, while Class 2 gases (krypton, xenon, nitrous oxide) are potent inhibitors, with effects modulated by pressure and temperature.
Area of Science:
- Microbiology
- Biophysics
Background:
- Hyperbaric environments can influence microbial physiology.
- Gases at elevated pressures can exhibit various biological effects, including growth inhibition and modification.
Purpose of the Study:
- To investigate the differential effects of various gases (helium, nitrogen, argon, krypton, xenon, nitrous oxide) on the growth of Escherichia coli, Saccharomyces cerevisiae, and Tetrahymena thermophila under hydrostatic pressure.
- To classify gases based on their growth-modifying actions and elucidate the mechanisms behind these effects.
Main Methods:
- Exposure of microbial cultures (E. coli, S. cerevisiae, T. thermophila) to different hyperbaric gases (He, N2, Ar, Kr, Xe, N2O) at varying pressures and temperatures.
- Quantification of growth inhibition and assessment of gas interactions with hydrostatic pressure and oxygen toxicity.
Main Results:
- Gases were categorized into Class 1 (He, N2, Ar – non-inhibitory, can reverse pressure inhibition) and Class 2 (Kr, Xe, N2O – potent inhibitors).
- Nitrous oxide (N2O) demonstrated significant growth inhibition, with specific pressure thresholds for different microbes (e.g., 0.5 MPa for T. thermophila at 24°C).
- Class 1 gases potentiated growth inhibition by Class 2 gases and oxygen, suggesting a gas-specific effect rather than a pressure effect.
Conclusions:
- Microbial growth modification by hyperbaric gases is not solely attributable to narcosis but involves distinct physiological actions.
- The findings differentiate gas effects, highlighting Class 1 gases' ability to counteract inhibition and Class 2 gases' potent inhibitory roles, influenced by temperature and pressure.