Fixation of carbon dioxide in Hydrogenomonas facilis as induced by preliminary oxyhydrogen reaction.

Abstract

1. Using a Knallgas bacterium, Hydrogenomonas facilis, dependence of its CO2-fixing capacity upon the process of Knallgas reaction was investigated under various experimental conditions. 2. The CO2-fixation coupled with the Knallgas reaction occurred strongly in bacterial cells which had been grown autotrophically in an oxyhydrogen atmosphere, while it was almost nil when the bacterium was grown heterotrophically using lactate as carbon source. In both autotrophically and heterotrophically grown cells lactate was found to accelerate the CO2-fixation in air (i. e., in the absence of oxyhydrogen), indicating the utilization of the energy of lactate oxidation for the CO2-fixation. 3. With the autotrophically grown cells, it was demonstrated that by the pre-incubation of cells in an oxyhydrogen atmosphere in the absence of CO2, the cells acquired a capacity of fixing CO2 on being brought in contact with CO2 in nitrogen or in air with cessation of oxyhydrogen reaction. The maximum level of this capacity in question was found to be attained in about 30 minutes of pre-incubation in the oxyhydrogen atmosphere (at 30°). 4. On removal of hydrogen from the gas mixture after a sufficient period of pre-incubation in the oxyhydrogen atmosphere, there occurred a decay in the acquired CO2-fixing capacity, the decay being more rapid in nitrogen atmosphere than in air.