1887

Abstract

Studies of rates of consumption of dissolved O by suspensions of bacteroids (, strain CB1809) from soybean root nodules showed the presence of two different terminal oxidase systems. A high-affinity system, sensitive to inhibition by -phenylimidazole and by carbon monoxide, was most active when the dissolved O was between 0.01 and 0.1 μM. At 1 μM-0 or higher, this oxidase system had little activity and 0 was consumed largely by a low-affinity system insensitive to these inhibitors. At low concentrations of dissolved 0, bacteroid respiration rates appeared to be diffusion-limited. When purified oxyleghaemo-globin was added to such systems, this restriction was relieved and respiration was maintained to much lower concentrations of free dissolved 0 here nitrogenase activity was greatest.

Analysis of reactions which were terminated at various stages during the depletion of 0 from oxyleghaemoglobin showed that at low free 0 concentration, the high-affinity pathway produced up to five times greater bacteroid ATP concentrations than the low-affinity oxidase pathway operating about 1 μM free 0 in the absence of leghaemoglobin. At intermediate free 0 concentrations, ocfnring during the later stages of deoxygenation of oxymyoglobin, intermediate concentrations of ATP were found in the bacteroids.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-91-2-345
1975-12-01
2020-01-26
Loading full text...

Full text loading...

http://instance.metastore.ingenta.com/content/journal/micro/10.1099/00221287-91-2-345
Loading
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error