Autotrophic Growth and Nitrogen Fixation in Derxia gummosa Ravi Shankar, H. N. and Kennedy, I. R. and New, P. B.,, 132, 1797-1803 (1986), doi = https://doi.org/10.1099/00221287-132-7-1797, publicationName = Microbiology Society, issn = 1350-0872, abstract= Summary: Initial attempts to grow N2-fixing Derxia gummosa autotrophically on H2, CO2, O2 and N2 in a closed system yielded variable results. Poor growth was found to be due to rapid O2 depletion and the requirement for an agar surface. In a closed system, C2H2 reduction assays could not be carried out due to complete consumption of H2. Hence a flow-through culturing technique was developed to supply gases at a constant partial pressure and to perform C2H2 reduction assays in a continuous flow system. Hydrogenase of autotrophic D. gummosa was not inhibited by C2H2, even at 0.5 atm, and the K m of hydrogenase for H2 was approximately 0.15 atm. The effects of O2 and H2 on C2H2 reduction were examined, using the flow-through assay system. The rate of C2H2 reduction decreased below 0.074 atm H2, suggesting that ATP and reductant supply were limiting the nitrogenase activity., language=, type=