TY  - JA
AU  - Hartmann,A.
AU  - Burris,R.H.
AU  - Fu,H.
TI  - Influence of amino acids on nitrogen fixation ability and growth of Azospirillum spp
SN  - 0099-2240
U1  - 89-079421 
PY  - 1988///
KW  - Bacteria
KW  - Human nutrition
KW  - Organic compounds
KW  - Organic nitrogen compounds
KW  - Physiological functions
KW  - Soil biology
KW  - Spirillaceae
N1  - ref
N2  - The utilization of amino acids for growth and their effects on nitrogen fixation differ greatly among the several strains of each species of Azospirillum spp. that were examined. A. brasiliense grew poorly or not at all on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources. Nitrogen fixation by most A. brasiliense strains was inhibited only slightly even by 10 mM concentrations of these amino acids. However, A. lipoferum and A. amazonense grew very well on glutamate, aspartate, serine, or histidine as the sole nitrogen and carbon sources; nitrogen fixation (measured in presence of malate or sucrose) was severely inhibited by these amino acids. It was concluded that growth on histidine as the sole source of nitrogen, carbon, and energy may be used for the taxonomic characterization of Azospirillum spp. and for the selective isolation of A. lipoferum. The different utilization of various amino acids by Azospirillum spp. may be important for their establishment in the rhi zosphere and for their associative nitrogen fixation with plants. The physiological basis for the different utilization of glutamate by Azospirillum spp. was investigated further. A. brasiliense and A. lipoferum exhibited a high affinity for glutamate uptake (Km values for uptake were 8 and 40 micron resp.); the Vmax was 6 x higher in A. lipoferum than in A. brasiliense. At high substrate concentrations (10 mM), the nonsaturable compt of glutamate uptake was most active in A. lipoferum and A. amazonense. The glutamate dehydrogenase activity of A. lipoferum was 7 x higher and the glutamate oxalacetate transaminase activities were 3 to 5 x higher in A. lipoferum and A. amazonese than in A. brasiliense. Glutamate-grown A. brasiliense had high glutamine synthetase and ammonium uptake activities, whereas these activities were low in glutamate-grown A. lipoferum. Thus, Azospirillum spp. differ quantitatively and qualitatively in their amino acid metabolism
T2  - Applied and Environmental microbiology (USA). (Jan 1988). v. 54(1) p. 87-93
ER  -