Mekonnen A E, Prasanna Radha, Kaushik B D
Agricultural Office Dabat, North Gondar, Ethiopia.
Acta Biol Hung. 2002;53(3):367-80. doi: 10.1556/ABiol.53.2002.3.13.
Nitrogenase activity, ammonia excretion and glutamine synthetase (GS) activity were examined in five strains of Anabaena (A. anomala ARM 314, A. fertilissima ARM 742, A. variabilis ARM 310, A. oryzae ARM 313 and A. oryzae ARM 570) in the presence of 2.5 mM NO3-N (KNO3), 2.5 mM NH-4-N [(NH4)2SO4] and diatomic nitrogen (N2). Ammonium-N was more inhibitory to nitrogenase activity as compared to NO3-N in all the strains. Maximum GS activity was exhibited in NO3-N medium, irrespective of the cyanobacterial strains studied. Uninduced release of ammonia was observed in all the species, with A. oryzae ARM 313 and Anabaena variabilis ARM 310 exhibiting maximum excretion of 0.25-0.31 and 0.27-1.23 mu moles NH4 mg Chl(-1) respectively on the 15th day of incubation. The glutamine synthetase activity of A. oryzae ARM 313 was relatively very high as compared to Anabaena variabilis ARM 310. There was no nitrate reductase activity in any of the Anabaena sp. grown on NH3-N or N2-N on the 15th day of incubation.
在2.5 mM硝酸根氮（硝酸钾）、2.5 mM铵根氮[硫酸铵]和双原子氮（N₂）存在的情况下，对5株鱼腥藻（异常鱼腥藻ARM 314、肥育鱼腥藻ARM 742、多变鱼腥藻ARM 310、稻生鱼腥藻ARM 313和稻生鱼腥藻ARM 570）的固氮酶活性、氨排泄和谷氨酰胺合成酶（GS）活性进行了检测。在所有菌株中，与硝酸根氮相比，铵根氮对固氮酶活性的抑制作用更强。无论所研究的蓝藻菌株如何，在硝酸根氮培养基中均表现出最大的GS活性。在所有物种中均观察到氨的非诱导释放，在培养第15天时，稻生鱼腥藻ARM 313和多变鱼腥藻ARM 310分别表现出最大排泄量，为0.25 - 0.31和0.27 - 1.23微摩尔NH₄毫克叶绿素⁻¹。与多变鱼腥藻ARM 310相比，稻生鱼腥藻ARM 313的谷氨酰胺合成酶活性相对非常高。在培养第15天时，在以氨氮或氮气为氮源生长的任何鱼腥藻属中均未检测到硝酸还原酶活性。
