SUMMARY: Oxygen-limited (N2-fixing) chemostat cultures of Klebsiella pneumoniae supplied with a N-free medium were established by introducing low atmospheric O2 concentrations into the gas supply of anaerobic glucose-limited N2-fixing chemostat cultures; the molar growth yield for glucose and the efficiency of N2 fixation (µg N fixed/mg glucose consumed) were increased (by up to 82%) from the anaerobic values.
Acetylene-reducing activity was inhibited reversibly by O2 in samples from O2-limited and anaerobic glucose-limited chemostat cultures. Oxygen uptake rates in samples from these chemostat cultures were similar, but C2H2-reducing activity in samples from O2-limited chemostat cultures was more tolerant of low atmospheric O2 concentrations, in part because of a higher population density. In the absence of glucose, O2 was required at a low atmospheric concentration for C2H2 reduction in samples from either O2-limited or anaerobic glucose-limited chemostat cultures. The possibility is discussed that ATP generated from oxidative phosphorylation can be used for N2 fixation in K. pneumoniae.
BigginsD.R., PostgateJ.R.1971; Nitrogen fixation by extracts ofMycobacterium flavum 301, use of natural electron donors and oxygen sensitivity of cell-free preparations. European Journal of Biochemistry 19:408–415
DaltonH., PostgateJ.R.1969; Effect of oxygen on growth ofAzotobacter chroococcum in batch and continuous culture. Journal of General Microbiology 56:307–319
DrozdJ., PostgateJ.R.1970; Effects of oxygen on acetylene reduction, cytochrome content and respiratory activity ofAzotobacter chroococcum. Journal of General Microbiology 63:63–73
HarrisonD.E.F.1972; A study of the effect of growth conditions on chemostat-grownKlebsiella aerogenes and kinetic changes of a 500 nm absorption band. Biochimica et biophysica acta 275:83–92
HarrisonD.E.F., LovelessJ.E.1971; The effect of growth conditions on respiratory activity and growth efficiency in facultative anaerobes grown in chemostat culture. Journal of General Microbiology 68:35–43
HarrisonD.E.F., PirtS.J.1967; The influence of dissolved oxygen concentration on the respiration and glucose metabolism ofKlebsiella aerogenes during growth. Journal of General Microbiology 46:193–211
HillS.1975; Acetylene reduction byKlebsiella pneumoniae in air related to colony dimorphism on low fixed nitrogen. Journal of General Microbiology 91:207–209
HillS., DrozdJ.W., PostgateJ.R.1972; Environmental effects on the growth of nitrogen-fixing bacteria. Journal of Applied Chemistry and Biotechnology 22:541–558
MöllerM.K., OttolenghiP.1966; The oxidation of o-dianisidine by H2O2and peroxidase at neutral pH. Comptes rendus des travaux du Laboratoire Carlsberg 35:369–389
PirtS.J.1957; The oxygen requirement of growing cultures of anAerobacter species determined by means of the continuous culture technique. Journal of General Microbiology 16:59–75
Rliiz-HerreraJ., AlvarezA.1972; A physiological study of formate dehydrogenase, formate oxidase and hydrogenylase fromEscherichia colik-12. Antonie van Leeuwenhoek 38:479–491
WimpennyJ.W.T.1969; Oxygen and carbon dioxide as regulators of microbial growth and metabolism. Symposium of the Society for General Microbiology 19:161–197
YatesM.G.1970; Control of respiration and nitrogen fixation by oxygen and adenine nucleotides in N2-grownAzotobacter chroococcum. Journal of General Microbiology 60:393–401
YochD.C.1974; Electron transport carriers involved in nitrogen fixation by the coliform Klebsiella pneumoniae. Journal of General Microbiology 83:153–164