HYDROGEN EFFECT IN RHODOSPIRILLUM-RUBRUM AND RHODOSPIRILLUM-FULVUM

Addition of 25% H-2 to the gas phase reduced the growth rate of the purple bacteria Rhodospirillum rubrum and Rhodospirillum fulvum under photoheterotrophic conditions. The presence of 2% CO2 in the gas phase eliminated the above-mentioned effect of molecular hydrogen. In this case a change in the content and ratio of pyridine nucleotides in the cells was found. With R. rubrum the hydrogen effect was accompanied by a decrease and with R. fulvum the hydrogen effect was accompanied by a certain increase in the level of reduced pyridine nucleotides. The kinetics of the growth rate transition processes and the level of reduced pyridine nucleotides indicates that the extent of reduction of the pyridine nucleotides was not the cause of the hydrogen effect at least in the purple non-sulfur bacteria.