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首页> 外文期刊>Journal of bacteriology >Selective inactivation of nitrogenase in Azotobacter vinelandii batch cultures.
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Selective inactivation of nitrogenase in Azotobacter vinelandii batch cultures.

机译：葡萄固氮菌分批培养物中的氮酶选择性失活。

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When the exhaustion of sucrose or sulfate or the induction of encystment (by incubation in 0.2% beta-hydroxybutyrate) leads to termination of growth in Azotobacter vinelandii batch cultures, the nitrogenase levels in the organisms decreased rapidly, whereas glutamate synthase and glutamine synthetase levels remained unaltered. Glutamate dehydrogenase activities were low during the whole culture cycle, indicating that ammonia assimilation proceeds via glutamine. Toward depletion of sucrose or during induction of encystment, slight secretion of ammonia with subsequent reabsorption was occasionally observed, whereas massive ammonia excretion occurred when the sulfate became exhausted. The extracellular ammonia levels were paralleled by changes in the glutamine synthetase activity. The inactivation of the nitrogenase is explained as a result of rising oxygen tension, a consequence of a metabolic shift-down (reduced respiration) that occurs in organisms entering the stationary phase.
机译：当蔗糖或硫酸盐的耗尽或囊泡的诱导（通过在0.2％β-羟基丁酸中孵育）导致葡萄固氮菌分批培养物的生长终止时，生物体中的固氮酶水平迅速下降，而谷氨酸合酶和谷氨酰胺合成酶水平保持不变保持不变。在整个培养周期中，谷氨酸脱氢酶活性较低，表明氨吸收通过谷氨酰胺进行。在蔗糖耗尽或诱导包囊过程中，偶尔会观察到少量氨的分泌并随后被重吸收，而当硫酸盐耗尽时会大量排泄氨。细胞外氨水平与谷氨酰胺合成酶活性的变化平行。硝化酶的失活被解释为是由于氧气张力升高而引起的，这是进入静止期的生物体中发生的代谢下降（呼吸减少）的结果。

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