The Physiological Bases for Microbial Barotolerance.
Technical rept. no. 6 (Annual), 1 Apr 77-31 Mar 78,
ROCHESTER UNIV N Y DEPT OF MICROBIOLOGY
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Attempts to relate growth inhibitory actions of anesthetic gases to their narcotic potencies revealed that the two are not well correlated. Instead, it was apparent that bacterial growth inhibition by the gases is a unique class of actions that can be distinguished from general anesthetic or narcotic actions. Experiments with a series of bacteria indicated that there is a range of sensitivity to nitrous oxide and that nitrous oxide sensitivity is correlated with oxygen sensitivity. Staphylococcus aureus was more sensitive to the gases than was E. coli, and both were considerably more sensitive than was Streptococcus faecalis. For the streptococcus, which has only minimal capacity to metabolize oxygen and has protective peroxidase and superoxide dismutase enzymes, oxygen seemed to act mainly only as an anesthetic gas with a potency about equal to that of nitrous oxide. The uniqueness of the growth inhibitory action was evident also in the effects of gas combinations on E. coli growth. Helium and anesthetic gases, including argon and nitrogen, were found to potentiate oxygen toxicity. Preliminary experiments were conducted with the protozoan Tetrahymena pyriformis.