f Autotrophic Growth and Nitrogen Fixation in Derxia gummosa
- Authors: H. N. RAVI SHANKAR, I. R. KENNEDY, P. B. NEW
- First Published Online: 01 July 1986, Microbiology 132: 1797-1803, doi: 10.1099/00221287-132-7-1797
- Subject: Physiology And Growth
- Issue Published:
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.
© Society for General Microbiology 1986 | Published by the Microbiology Society
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