ISSN:
1573-5176
Schlagwort(e):
ammonium
;
cyanobacteria
;
nitrogenase activity
;
rice fields
;
sugar utilization
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract The nitrogen-fixing capacity of four cyanobacterial strains was tested in relation to heterotrophic ability, tolerance to combined nitrogen and adaptive capacity to changes in light intensity and pH. Strains (Anabaena variabilis UAM 202;Calothrix marchica UAM 214;Nodularia spumigena UAM 204,Nostoc punctiforme UAM 205) were isolated from the rice-fields of Valencia (Spain).C. marchica, was the only strain able to grow and to fix dinitrogen under heterotrophic conditions, with fructose and glucose. Fructose was the best substrate supporting growth and dinitrogen fixation in mixotrophy (growth in the light under conditions where CO2 and organic carbon are assimilated simultaneously), photoheterotrophy (growth in the light on an organic compound in the absence of net CO2 fixation) and heterotrophy (growth on an organic compound in the dark). Ammonium repressed nitrogenase more than nitrate. Full repression was observed only at concentrations of combined nitrogen higher than those usually found in rice-fields. Carbohydrates had a protective effect on nitrogenase against ammonium inhibition inC. marchica. All four strains showed increased nitrogenase activity when the light intensity was increased during assays. Variations of pH normally occurring in rice fields led to no important changes in nitrogenase activity inC. marchica. This fact, together with its potential for heterotrophic growth and tolerance to combined nitrogen, make this the most suitable of the four strains for inoculation experiments in rice fields.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02161205
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