Occurrence and activity of hydrogenase in symbiotic Frankia from field-collected Alnus incana |
| |
Authors: | Anita Sellstedt |
| |
Institution: | Dept of Plant Physiology, Univ. of Umeå, S-901 87 Umeå, Sweden. |
| |
Abstract: | Occurrence and activity of the hydrogen uptake enzyme were studied in root nodule homogenates made from plants of Alnus incana (L.) Moench collected from field sites in the northern part of Sweden. Nitrogenase (EC 1.7.99.2) activity (estimated by acetylene reduction) and hydrogen evolution were studied in excised nodules. All Frankia sources showed acetylene reduction activity, and possessed a hydrogen uptake system. Hydrogen uptake in nodule homogenates from the Frankia sources measured at 23.8 μM H2 ranged from 0.04 to 5.0 μmol H2 (g fresh weight nodule)?1 h?1. The H2 uptake capacity of nodule homogenates from one of the Frankia sources was almost 8 times higher than the hydrogen evolution from nitrogenase, both expressed on a nodule fresh weight basis. Frankia sources from field sites 6 and 11 showed Km for H2 of 13.0 and 23.6 μM H2, respectively. This indicates similarities in the hydrogen uptake enzymes in the two Frankia sources. It is concluded that hydrogen uptake is a common characteristic in Frankia. |
| |
Keywords: | Actinorhizal plants Alnus incana Frankia hydrogen evolution hydrogen uptake nitrogen fixation symbiosis |
|
|