Abstract
Harvey and Taylor 1 have shown that concentrated heavy water markedly inhibits the respiration of 2 species of luminous bacteria and diminishes the luminescence of one form (Bacillus fischeri). The effect on the respiration of Bacillus fischeri was such that if the curve relating effect on respiration with concentration of heavy water is extrapolated, zero respiration is indicated in 100% heavy water. Reduction of respiration of Vibrio phosphorescens was not so great.
Experiments with yeast indicate that the effect of heavy water on respiration of this organism is also not so great. These are detailed below together with a study of the respiration in as near 100% heavy water as is experimentally feasible considering the hygroscopic properties of D2O. Pacsu 2 has reported a 9-fold reduction of yeast fermentation (CO2 production) in approximately 100% D2O and 1.6 reduction in 60% D2O).
The heavy water was provided by Professor H. S. Taylor, and had been prepared by electrolysis and burning of deuterium and oxygen in the manner described by Taylor, Eyring and Frost. 3 It had also been distilled from alkali and permanganate. High concentrations of such water is toxic for paramoecium, whereas low concentrations, (0.2%) although prepared in exactly the same manner and also distilled from alkali and permanganate in the same vessel, are not toxic, so that the diminution of respiration of cells in concentrated heavy water must be connected with the deuterium which it contains and not with impurities of any kind. Yeast in contact with 0.2% D2O for 17 hours and control yeast in contact with distilled water for 17 hours both respire at the same rate (within 5%) when nutrient is added, showing that no deleterious impurities having a cumulative effect were present.
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