甘露醇对氯化钠胁迫下蓝藻Anabaena 7120固氮活性的增强效应

ENHANCING EFFECT OF MANNITOL ON NITROGEN-FIXING ACTIVITY OF BLUE-GREEN ALGAE ANABAENA 7120 UNDER NaCI STRESS

摘要:

营养液中添加外源的甘露醇后，蓝藻Ａｎａｂａｅｎａ７１２０固氮受ＮａＣｌ胁迫的程度减弱．在光合作用不能进行或受到削弱、能量供应受阻（暗中或添加抑制剂）、厌氧环境（Ａｒ或Ｎ２中）和分子氧条件下，甘露醇的良好作用减小或消失。改善能源和碳架供应，增强氢的利用或满足合成固氮酶蛋白所需物质需求（提高ＣＯ２浓度，同时供应Ｈ２和Ｏ２或Ｎ２和ＣＯ２）时，甘露醇缓解ＮａＣｌ胁迫蓝藻固氮的程度明显增大．外源蔗糖对甘露醇的上述缓解效应无促进作用。

Abstract:

The NaCl-induced inhibition of nitrogen-fixing activity of blue-green algae Anabaena 7120 was removed to a certain degree by the. introduction of appropriaternannitol into the test system. When the preincubation of algae cells was done in dark before experiment for 24 hours or in the presence of photosynthetic inhibitors, such as DNP or CCCP, the enhancing effect of mannitol on the nitrogen-fixing activity of Anabaena 7120 supressed by NaCl weakened or disappeared. In the addition of O2 together with H2 the enhancing effect of mannitol on nitrogen-fixing activity of Anabaena 7120 was reinforced under NaCl stress. A marked inaction in nitrogen-fixing activity of Anabaena 7120 occurred under NaCl stress when O2 was introduced into the test system alone. When algae cells inactivited by NaCl were incubated in the aerobic condition the accelerated action of mannitol upon the nitrogen-fixing activity was higher than that in anaerobic condition. The mannitol-supported nitrogen-fixing activity of Anabaena 7120 under NaCl stress was accelerated in the addition of N2 together with CO2 or addition of CO2 alone, while it was depressed by adding N2 alone.