Issue Archive

Interrelationships of H_(2) and carbon metabolism in controlling and regulating nitrogen fixation activity in the Gunnera/Nostoc symbionts

Man Huimin, Silvester W B

Department of Basic Courses, Laiyang Agricultural College. Laiyang,Shandong

Abstract

The Gunnera/Nostoc symbionts evolved H_(2)through nitrogenase in a predictable manner. However, the relative efficiency of nitrogen fixation in the Gunnera/Nostoc symbionts varied widely from 0.26 to 0.80. Nitrogen fixation activity was carbohydrate-limited in normal growth conditions and glucose addition(1.5%) rapidly increased nitrogen fixation activity and respiratory rate with a maximum stimulation of ca. 100% and 160% respectively. The stimulation of nitrogen fixation activity was also affected by H_(2)addition, when the maximum stimulation of ca. 100% occurred in seriously carbohydrate-limited condition. However, respiration rate decreased by about 50% on H_(2) addition. Net H_(2) evolution was strongly stimulated by slucose addition. In addition, nitrogen fixation activity decreased by about 70% on the addition of NH_(4)Cl. It is postulated that carbohydrate supply and uptake hydrogenase could regulate the activity of nitrogen fixation by supplying a common reductant pool and that the recycling of H_(2) through nitrogenase, when (CH_(2)O)_(n) supply was low, could sustain nitrogenase at a reasonably high level and could thus be able to take advantage of an...

Key words: Gunnera/Nostoc symbiont;Nitrogenase;Hydrogenase;Relative efficiency of nitrogen fixation;Hydropn evolution

Received: 　　Accepted:

Corresponding author: 　　E-mail:

Citing This Article：

Man Huimin, Silvester W B. Interrelationships of H_(2) and carbon metabolism in controlling and regulating nitrogen fixation activity in the Gunnera/Nostoc symbionts. Acta Physiol Sin 1994; 46 (1): (in Chinese with English abstract).