Rediers Hans, Vanderleyden Jos, De Mot René
Centre of Microbial and Plant Genetics, Katholieke Universiteit Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee, Belgium.
Microbiol Res. 2009;164(4):461-8. doi: 10.1016/j.micres.2007.03.003. Epub 2007 Apr 30.
Unlike most bacteria, the nitrogen-fixing rice-associated Pseudomonas stutzeri A15 disposes of three different nitrate reductases that enable conversion of nitrate to nitrite through three physiologically distinct processes, called nitrate assimilation, nitrate respiration and nitrate dissimilation. To study the role of nitrate respiration in rhizosphere fitness, a Pseudomonas stutzeri narG mutant was constructed and characterized by assessing its growth characteristics and whole-cell nitrate reductase activity in different oxygen tensions. Unexpectedly, the Pseudomonas stutzeri A15 narG mutant appeared to be a better root colonizer, outcompeting the wild type strain in a wheat and rice hydroponic system.
与大多数细菌不同，与水稻相关的固氮施氏假单胞菌A15具有三种不同的硝酸还原酶，可通过三种生理上不同的过程将硝酸盐转化为亚硝酸盐，这三种过程分别称为硝酸盐同化、硝酸盐呼吸和硝酸盐异化。为了研究硝酸盐呼吸在根际适应性中的作用，构建了施氏假单胞菌narG突变体，并通过评估其在不同氧张力下的生长特性和全细胞硝酸还原酶活性对其进行了表征。出乎意料的是，施氏假单胞菌A15 narG突变体似乎是更好的根部定殖菌，在小麦和水稻水培系统中比野生型菌株更具竞争力。
