蓝藻Anabaena7120的固氮活力及其和光合作用的关系

蓝藻Anabaena 7120经用Ar+CO_2、空气和Ar处理后,固氮活性有明显不同。Ar+CO_2处理的活性比空气处理的高出数倍,而Ar处理的则比空气中的低很多。以上三种处理的Anabaena 7120固氮对不同生理条件反应不一样,固氮活性高者对CO和O_2的敏感程度小些、受到CO_2和N_2的抑制程度也轻。但是分子氢对三者固氮作用的支持效用相同,并且也是和氢酶活动有联系。弱光下固氮活力低的蓝藻固氮活性下降得更大些。光合抑制剂和结合态氮对固氮活力高的蓝藻固氮活性的抑制显著比固氮活力低者小。三者的放氢和放氧能力也不同,固氮活力高者放氧高而放氢量小些,低固氮活力的蓝藻正好相反。

NITROGEN FIXATION ACTIVITY OF ANABAENA 7120 AND ITS RELATION TO PHOTOSYNTHESIS

Blue-green alage Anabaena 7120 was used to investigate the nitrogen fixation and its relation to photosynthesis. The following results were obtained.Under an atmosphere containing 95% Ar and 5% CO_2 or 100% Ar the C_2H_2-reducing activity of Anabaena 7120 was much higher or lower, respectively, than that in air. Moreover, the response to physiological conditions of nitrogen fixation also differed. When the algae was incubated in CO_2, N_2, O_2 or CO respectively, the extent of inhibition of nitrogen fixation in Anabaena 7120 with lower nitrogenfixing activity was greater than in one with higher activity. H_2-supported nitrogen fixation in Anabaena 7120, in accord with its nitrogen-fixing activity. Under weak light or in the presence of photosynthetic inhibitors such as DNP, CCCP, NaN_3, DCMU and salicylaldoxime or combined nitrogen such as ammonia chloride and urea in the reaction system; the inhibition of C_2H_2-reduction was more pronounced in Anabaena 7120 with lower nitrogen-fixing activity. O_2-evolution was much less, while H_2-evolution was not as much in Anabaena 7120 with lower nitrogenfixing activity.According to the above results, there is a close relation between nitrogen fixation, photosynthesis and nitrogen-fixing activity in Anabaena 7120.