@article{mbs:/content/journal/micro/10.1099/00221287-132-7-1797, author = "Ravi Shankar, H. N. and Kennedy, I. R. and New, P. B.", title = "Autotrophic Growth and Nitrogen Fixation in Derxia gummosa", journal= "Microbiology", year = "1986", volume = "132", number = "7", pages = "1797-1803", doi = "https://doi.org/10.1099/00221287-132-7-1797", url = "https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-132-7-1797", publisher = "Microbiology Society", issn = "1465-2080", type = "Journal Article", 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.", }