摘要
柱孢鱼腥藻生长在缺氮情况下,发现其固氮活性增加的同时也减少了对氧的敏感性。缺氮生长细胞的乙炔还原活性给氧抑制一半时的氧分压(pO_2)是0.5atm.,而有氮生长细胞的半抑制浓度为0.35atm.。这表明蓝藻有可能通过增加呼吸耗氧而提高了它的固氮酶活性。呼吸作用与固氮酶活性之间存在着密切的关系。无论在有氮、缺氮还是光诱导固氮酶形成的情况下,其固氮活性均随着呼吸速率的变化而变化。本研究结果,支持了柱孢鱼腥藻固氮酶的主要防氧手段是呼吸保护的观点。
When A. cylindrica was grown under the condition of N_2-deficiency, an increase in N_2-fixing activity and a decrease in oxygen sensitivity were found simultaneously. The acetylene reduction was inhibited by 50% by 0.5 atm. partial pressure of oxygen (pO_2) in the N2-deficient algal cells, and by 0.35 atm. pO_2 in the N_2-sunfieient algal cells. It indicates that the enhanced nitrogenase activity is possibly due to an increase in respiratory (Vconsnmptiion of the alga.Further research suggests that there is close relationship between respiration and nitrogenase activity. 'When the alga grew under such conditions as N_2-sufficiency, N_2-deficiency and light induced nitrogenase synthesis, the N_2-fixing activity varied with respiration rate correspondingly. Our results support the concept that the main means of nitrogenase against O_2 damage is respiration protection.
