Journal article
Ammonium uptake by cowpea Rhizobium strain MNF 2030 and Rhizobium trifolii MNF 1001
Archives of Microbiology, Vol.149(4), pp.308-311
1988
Abstract
Free-living Rhizobium trifolii MNF 1001 and cowpea Rhizobium MNF 2030 grown in chemostat culture under nitrogen limitation had high activities of an ammonium permease. In phosphate-limited, nitrogen-excess conditions, strains MNF 1001 and MNF 2030 retained 20% and 50%, respectively, of the ammonium uptake activity found in nitrogen-limited cells. Uptake in both strains was sensitive to azide, cyanide, carbonyl cyanide m-chlorophenyl hydrazone and 2,4-dinitrophenol. A gradient of ammonium concentration greater than 150-fold developed across the membrane within 20 min in cells of strain MNF 1001 grown under ammonia limitation. The pH optimum for ammonium uptake by N-limited cells of both MNF 1001 and MNF 2030 was around pH 7. The apparent Km values for the ammonium permease in strains MNF 2030 and MNF 1001 were 3.9±1.6 μM and 2.0±1.6 μM respectively, and the Vmax was 47±2.6 nmol min-1 (mg protein)-1 for MNF 2030 and 101±5.1 nmol min-1 (mg protein)-1 for MNF 1001. Isolated snake bean bacteroids of strain MNF 2030 capable of transporting succinate and l-glutamate had no detectable ammonium uptake activity. It therefore appears that the ammonium permeases in cells of these two strains are not as tightly regulated as in R. leguminosarum MNF 3841.
Details
- Title
- Ammonium uptake by cowpea Rhizobium strain MNF 2030 and Rhizobium trifolii MNF 1001
- Authors/Creators
- H.N. Jin (Author/Creator)A.R. Glenn (Author/Creator)M.J. Dilworth (Author/Creator)
- Publication Details
- Archives of Microbiology, Vol.149(4), pp.308-311
- Publisher
- Springer Verlag
- Identifiers
- 991005543946507891
- Copyright
- © 1988 Springer-Verlag.
- Murdoch Affiliation
- School of Environmental and Life Sciences
- Language
- English
- Resource Type
- Journal article
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- Citation topics
- 3 Agriculture, Environment & Ecology
- 3.97 Plant Pathology
- 3.97.892 Rhizobium-Legume Symbiosis
- Web Of Science research areas
- Microbiology
- ESI research areas
- Microbiology