Effect of High Pressures of Pure Oxygen on Tissues

Journal/Book: Reprinted from Nature Vol. 201 No. 4918 pp. 514-515 February 1 1964. 1964;

Abstract: Department of Botany University of Exeter. IN the course of some investigations carried out in the Botany School Cambridge between 1927 and 1930 it was found that pressures of the order of 5 atmospheres and more of pure oxygen had an unexpected effect on the production of carbon dioxide from the tissues of higher plants. I postulated that the effect of the pressures was to inhibit completely the activity of the respiratory enzyme systems since carbon dioxide production ceased. This theory was elaborated by me in 19311. At a much later date these findings were further developed2. This inhibitory effect of high pressures of pure oxygen was confirmed by subsequent workers and later work showed that the respiratory enzyme systems were inhibited3 4. Other workers showed that similar effects were found in experiments with animal tissues5 6. Experiments with fungi. More recently7 I directed attention to the effect of similar pressures of pure oxygen on the metabolism of some fungi. In the earlier experiments already noted it had been observed that the high oxygen pressures had an inhibitory effect on the metabolism of bacteria and fungi and this was commented on in ref. 1. Subsequent experiments on fungi have confirmed this observation. In fungi unlike higher plants recovery appears to be possible in all the species so far examined in this laboratory if the exposure to 10 atmospheres or so of pure oxygen is of a relatively short duration for example 3 days. Some fungi were found to recover after much longer exposures while Aspergillus niger was found to recover and to recommence growth after 18 days but not after 28 days exposure to that pressure of oxygen. Clearing fungal cultures of mites. It was thought that this ability of fungi to withstand considerable pressures of oxygen for some days might be used to develop a simple method of killing the mites which tend to appear from time to time in fungal cultures in collections. In a preliminary set of experiments the buds of black currant affected with big bud mite (Eriophyes ribis) were used. After 24 h at 10 atmospheres of pure oxygen all the mites were completely killed and the bud scales had turned brown and were clearly 'poisoned'. This is in line with earlier observations on the tissues of higher plants. Subsequent experiments with cheese mites and with the mites growing on fungal cultures showed that very much lower concentrations of oxygen could be used to kill them. ... ___MH

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